JPH11186255A - Method of forming silicon oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid causing irregularities by starting forming an Si oxide film by an oxidation method using a wet gas at an atmosphere temp. at which no Si atom releases from the Si layer surface to form the Si oxide film of desired thickness by the oxidation method using a wet gas. SOLUTION: An Si oxide film 42 is formed on the surface of an Si semiconductor substrate 40 by the oxidation method using a wet gas at an atmosphere temp. held at which no Si atom separates from the Si semiconductor substrate 40 surface and an Si oxide film 42 is formed on the surface of the Si semiconductor substrate 40 by the oxidation method using a wet gas at an atmosphere temp. held higher than the atmosphere temp. at which no Si atom separates from the Si semiconductor substrate 40. This avoids causing irregularities on the Si layer surface and improves the characteristics of the Si oxide film not contg. a dry oxide film of a less reliability in the finally formed Si oxide film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a silicon oxide film in the manufacture of a semiconductor device, for example.

[0002]

2. Description of the Related Art For example, in manufacturing a MOS type semiconductor device, it is necessary to form a gate oxide film made of a silicon oxide film on the surface of a silicon semiconductor substrate. Also, in manufacturing a thin film transistor (TFT), it is necessary to form a gate oxide film made of a silicon oxide film on the surface of a silicon layer provided on an insulating substrate. It is not an exaggeration to say that such a silicon oxide film is responsible for the reliability of the semiconductor device. Therefore, a silicon oxide film is always required to have high dielectric breakdown voltage and long-term reliability.

[0003] For example, in the case of manufacturing a MOS type semiconductor device, conventionally, NH ₄ OH /
The surface of the silicon semiconductor substrate is cleaned by RCA cleaning in which the surface is washed with an H ₂ O ₂ aqueous solution and further washed with an HCl / H ₂ O ₂ aqueous solution, and fine particles and metal impurities are removed from the surface. When the RCA cleaning is performed, the surface of the silicon semiconductor substrate reacts with the cleaning liquid to form a silicon oxide film having a thickness of about 0.5 to 1 nm (hereinafter, such a silicon oxide film is simply referred to as an oxide film). The thickness of such an oxide film is not uniform, and the cleaning liquid component remains in the oxide film. Therefore, the silicon semiconductor substrate is immersed in a hydrofluoric acid aqueous solution to remove such an oxide film, and further, a chemical component is removed with pure water. Thereby, it is possible to obtain a surface of the silicon semiconductor substrate that is mostly terminated with hydrogen and extremely partially terminated with fluorine. In this specification, obtaining a surface of a silicon semiconductor substrate that is mostly terminated with hydrogen and a very small portion is terminated with fluorine is referred to as exposing the surface of the silicon semiconductor substrate in this specification. I do. Thereafter, the silicon semiconductor substrate is carried into a processing chamber (oxidizing furnace) of the silicon oxide film forming apparatus, and a silicon oxide film is formed on the surface of the silicon semiconductor substrate.

[0004] As the silicon oxide film forming apparatus, as the gate oxide film becomes thinner and the substrate becomes larger in diameter, a quartz-type processing chamber (oxidizing furnace) is held horizontally and a vertical method is held vertically. Are shifting to silicon oxide film forming apparatuses. This is because the vertical type silicon oxide film forming apparatus is easier to cope with the enlargement of the substrate diameter than the horizontal type silicon oxide film forming apparatus, and also when the silicon semiconductor substrate is carried into the processing chamber. This is because a silicon oxide film generated by entrainment in the atmosphere (hereinafter, such a silicon oxide film is referred to as a natural oxide film) can be reduced.
However, even when a vertical silicon oxide film forming apparatus is used, a natural oxide film having a thickness of about 2 nm is formed on the surface of the silicon semiconductor substrate. The natural oxide film contains a large amount of impurities in the atmosphere, and the existence of the natural oxide film cannot be ignored in thinning the gate oxide film. Therefore, (1) a method of flowing a large amount of nitrogen gas into the substrate loading / unloading section provided in the silicon oxide film forming apparatus to form a nitrogen gas atmosphere (nitrogen gas purge method), (2)
Once the inside of the substrate loading / unloading section is evacuated, a method of replacing the inside of the substrate loading / unloading section with an inert gas such as nitrogen gas and eliminating the atmosphere (vacuum load lock method) is adopted. Methods for suppressing formation have been proposed.

[0005] Then, the silicon semiconductor substrate is carried into the processing chamber (oxidizing furnace) with the processing chamber (oxidizing furnace) in an inert gas atmosphere, and then the processing chamber (oxidizing furnace) is oxidized. The gate oxide film is formed by switching and heat-treating the silicon semiconductor substrate. A method of thermally oxidizing the surface of a silicon semiconductor substrate by introducing high-purity water vapor into a processing chamber maintained at a high temperature (wet oxidation method) is used for forming a gate oxide film. A gate oxide film with higher electrical reliability can be formed than a method of oxidizing the surface of a silicon semiconductor substrate with oxygen gas (dry oxidation method). As one of the wet oxidation methods, there is a pyrogenic oxidation method (also called a hydrogen gas combustion oxidation method) in which water vapor generated by mixing hydrogen gas with oxygen gas at a high temperature and burning it is used for forming a silicon oxide film. , Has been adopted a lot. Usually, in this pyrogenic oxidation method, oxygen gas is supplied to a combustion chamber provided outside a processing chamber (oxidizing furnace) and maintained at 700 to 900 ° C., and then hydrogen gas is supplied to the combustion chamber. Then, the hydrogen gas is burned at a high temperature. The water vapor thus obtained is used as an oxidizing species.

FIG. 13 is a conceptual diagram of a vertical type silicon oxide film forming apparatus for forming a silicon oxide film based on a pyrogenic oxidation method. This vertical type silicon oxide film forming apparatus includes a processing chamber 10 having a double tube structure made of quartz held in a vertical direction, a gas introduction unit 12 for introducing water vapor and / or gas into the processing chamber 10, A gas exhaust unit 13 for exhausting water vapor and / or gas from the processing chamber 10; a heater 14 for maintaining the inside of the processing chamber 10 at a predetermined atmospheric temperature via a cylindrical heat equalizing pipe 16 made of SiC; Unit 20, a gas introduction unit 21 for introducing an inert gas such as nitrogen gas into and out of substrate loading / unloading unit 20, and a substrate loading / unloading unit 2
A gas exhaust unit 22 for exhausting gas from zero, a shutter 15 for separating the processing chamber 10 from the substrate loading / unloading unit 20, and an elevator mechanism 23 for transporting the silicon semiconductor substrate into and out of the processing chamber 10. . Elevator mechanism 23
Is mounted with a quartz boat 24 for mounting a silicon semiconductor substrate. Further, the hydrogen gas supplied to the combustion chamber 30 is mixed with the oxygen gas at a high temperature in the combustion chamber 30 and burned to generate steam.
The water vapor is introduced into the processing chamber 10 through the pipe 31, the gas flow path 11, and the gas introduction unit 12. The gas flow path 11 corresponds to a space between the inner wall and the outer wall of the processing chamber 10 having a double pipe structure.

An outline of a conventional silicon oxide film forming method based on a pyrogenic oxidation method using the vertical type silicon oxide film forming apparatus shown in FIG. 13 will be described with reference to FIGS. 13 and 67 to 69. This will be described below.

[Step-10] Nitrogen gas is introduced into the processing chamber 10 through the pipe 32, the combustion chamber 30, the pipe 31, the gas flow path 11 and the gas introduction unit 12, and the inside of the processing chamber 10 is set to a nitrogen gas atmosphere. Further, the atmosphere temperature in the processing chamber 10 is maintained at 700 to 800 ° C. by the heater 14 via the soaking tube 16. In this state, the shutter 15 is closed (see FIG. 67A). The substrate loading / unloading section 20 is open to the atmosphere.

[Step-20] The substrate loading / unloading section 20
Then, the silicon semiconductor substrate 40 is carried in, and the silicon semiconductor substrate 40 is placed on the quartz boat 24. Substrate loading / unloading section 20
After the loading of the silicon semiconductor substrate 40 into the substrate is completed, a door (not shown) is closed, nitrogen gas is introduced from the gas introduction unit 21 into the substrate loading / unloading unit 20, discharged from the gas exhaust unit 22, and discharged into the substrate loading / unloading unit 20. In a nitrogen gas atmosphere (see FIG. 67B).

[Step-30] When the inside of the substrate loading / unloading section 20 has a sufficient nitrogen gas atmosphere, the shutter 15 is opened (see FIG. 68B), the elevator mechanism 23 is operated, and the quartz boat 24 is operated. Is raised, and the silicon semiconductor substrate 40 is carried into the processing chamber 10 (see FIG. 69A). When the elevator mechanism 23 reaches the highest position,
The base of the quartz boat 24 prevents communication between the processing chamber 10 and the substrate loading / unloading section 20.

If the processing chamber 10 is left in a nitrogen gas atmosphere before the shutter 15 is opened, the following problems occur. That is, when the silicon semiconductor substrate whose surface is exposed by washing with a hydrofluoric acid aqueous solution and pure water is carried into a high-temperature nitrogen gas atmosphere, the silicon semiconductor substrate 40
The surface becomes rough. This phenomenon occurs because part of the Si—H bond and part of the Si—F bond formed on the surface of the silicon semiconductor substrate 40 by washing with the hydrofluoric acid aqueous solution and the pure water are heated and desorbed by hydrogen and fluorine. It is considered that the loss is caused by separation and that the etching phenomenon occurs on the surface of the silicon semiconductor substrate 40. For example, when the temperature of a silicon semiconductor substrate is raised to 600 ° C. or more in an argon gas, severe irregularities may occur on the surface of the silicon semiconductor substrate.
I Technology ", page 21. In order to suppress such a phenomenon, before opening the shutter 15, for example, a nitrogen gas containing about 0.5% by volume of oxygen gas is introduced from the gas introduction unit 12 into the processing chamber 10. The inside is set to a nitrogen gas atmosphere containing about 0.5% by volume of oxygen gas (see FIG. 68A).

[Step-40] Thereafter, the atmosphere temperature in the processing chamber 10 is set to 800 to 900 ° C. And piping 3
Oxygen gas and hydrogen gas are supplied into the combustion chamber 30 via the combustion chambers 2 and 33, and the hydrogen gas is mixed with the oxygen gas at a high temperature in the combustion chamber 30 and steam generated by burning the mixture.
The gas is introduced into the processing chamber 10 through the pipe 31, the gas flow path 11, and the gas introduction unit 12, and is exhausted from the gas exhaust unit 13 (FIG. 6).
9 (B)). Thus, a silicon oxide film is formed on the surface of the silicon semiconductor substrate 40. In order to prevent a detonation reaction from occurring due to the incompletely burned hydrogen gas flowing into the processing chamber 10 before introducing steam into the processing chamber 10, the hydrogen gas is supplied from the pipe 33 to the combustion chamber 30. Before supplying the oxygen gas, oxygen gas is supplied to the combustion chamber 30 via the pipe 32. As a result, the pipe 31, the gas flow path 1
Oxygen gas flows into the processing chamber 10 through the gas inlet 1 and the gas inlet 12. The temperature in the combustion chamber 30 is maintained at 700 to 900 ° C. by, for example, a heater (not shown).

[0013]

Before the shutter 15 is opened, a nitrogen gas containing about 0.5% by volume of oxygen gas is introduced into the processing chamber 10 from the gas introducing section 12, and the processing chamber 10 is opened.
By setting the inside of the inside to a nitrogen gas atmosphere containing about 0.5% by volume of oxygen gas (see FIG. 68A), a phenomenon in which unevenness is formed on the surface of the silicon semiconductor substrate can be suppressed. Alternatively, "Ultra Clean ULSI Technology", published by Baifukan and written by Tadahiro Omi, page 21, states that a hydrogen-terminated silicon semiconductor substrate is subjected to dry oxidation at 300 ° C. where terminal hydrogen is stably present and formed by this method. It has been reported that the problem of forming irregularities on the surface of a silicon semiconductor substrate can be avoided by using the formed silicon oxide film as a protective film.

However, since nitrogen gas containing oxygen gas is introduced into the processing chamber 10 in order to suppress the phenomenon that unevenness is formed on the surface of the silicon semiconductor substrate, the silicon carried into the processing chamber 10 is not introduced. A silicon oxide film is formed on the surface of the semiconductor substrate. Such a silicon oxide film is essentially a silicon oxide film formed by so-called dry oxidation (called a dry oxide film), and a silicon oxide film formed by a wet oxidation method (called a wet oxide film). Inferior in characteristics. For example, the inside of the processing chamber 10 is maintained at 800 ° C., and a silicon semiconductor substrate is placed in the processing chamber 10 while a nitrogen gas containing 0.5% by volume of oxygen gas is introduced into the processing chamber 10 from the gas introduction unit 12. Then, a dry oxide film of 2 nm or more is formed on the surface of the silicon semiconductor substrate. In a semiconductor device having a gate length of 0.18 to 0.13 μm, it is expected that a gate oxide film having a thickness of 4 to 3 nm will be used. Thus, for example, when an attempt is made to form a gate oxide film having a thickness of 4 nm, 50% or more of the thickness is occupied by the dry oxide film.

A means for solving such a problem is disclosed in Japanese Patent Application Laid-Open No. 6-291112. That is, this patent discloses a technique in which a silicon semiconductor substrate is washed with an aqueous solution of hydrofluoric acid, and then the silicon semiconductor substrate is immersed in a hydrogen peroxide solution to form a silicon oxide film as a protective film on the surface of the silicon semiconductor substrate. It is disclosed in the publication. However, in this method, it is difficult to form a uniform silicon oxide film on the surface of the silicon semiconductor substrate with good reproducibility by controlling the concentration of hydrogen peroxide solution or the like. There is also a problem that impurities in the hydrogen peroxide solution are taken into the silicon oxide film.

A method of forming a silicon oxide film having excellent long-term stability, high withstand voltage and a small thickness is described in, for example,
It is disclosed in JP-A-6-318588. In this method, an ultrathin thermal oxide film is formed on the surface of a silicon semiconductor by a thermal oxidation method, and then a silicon oxide film is deposited on the ultrathin thermal oxide film by a vapor deposition method (CVD method). Heat treatment in an oxidizing atmosphere. In this method, since a silicon oxide film is deposited by a vapor phase growth method (CVD method), there is a problem that a process of forming the silicon oxide film is complicated.

The above problem occurs not only on the surface of a silicon semiconductor substrate but also on the surface of a silicon layer provided on an insulating substrate or an insulating layer.

In manufacturing a MOS type semiconductor device, it is necessary to form a silicon oxide film on a silicon semiconductor substrate before forming a gate oxide film. Such a silicon oxide film is formed by LOCOS (LOCal Oxidation of Silicon).
In the process of forming element isolation regions with a structure or trench structure,
It is an oxide film as a base for depositing a silicon nitride film (hereinafter sometimes referred to as a base oxide film) or a sacrificial oxide film before forming a gate oxide film. These underlying oxide films or sacrificial oxide films are also formed on the surface of the silicon semiconductor substrate, but these oxide films are not required to have the same electrical reliability as the gate oxide film. Therefore, in the formation of these oxide films, formation of a natural oxide film or surface roughness of a silicon semiconductor substrate is not usually considered. Therefore, when these oxide films are formed, the oxide film includes a natural oxide film, or an interface between the oxide film and the silicon semiconductor substrate has irregularities. By the way, these oxide films are removed by hydrofluoric acid cleaning before forming the gate oxide film. Therefore, such a natural oxide film included in the oxide film is also removed, so that there is no problem related to a decrease in reliability of the gate oxide film due to the natural oxide film. Anyway,
Irregularities remain on the surface of the silicon semiconductor substrate after these oxide films have been removed by hydrofluoric acid cleaning. Such irregularities left on the surface of the silicon semiconductor substrate may cause a decrease in the electrical reliability of a gate oxide film to be formed next. Therefore, the surface of the silicon semiconductor substrate before the gate oxide film is formed is required to be as flat as possible. In other words, the surface of the silicon semiconductor substrate after the formation of the element isolation region and the surface of the silicon semiconductor substrate after forming the sacrificial oxide film and then removing the sacrificial oxide film need to be as flat as possible.

Therefore, an object of the present invention is to prevent the surface of the silicon layer from being roughened (irregular) when forming a silicon oxide film on the surface of the silicon layer, and to dry oxidize the surface of the silicon layer. An object of the present invention is to provide a method for forming a silicon oxide film having excellent characteristics without forming a film.

[0020]

According to a first aspect of the present invention, there is provided a method of forming a silicon oxide film, the method comprising: Forming a silicon oxide film on the surface of the silicon layer by an oxidation method using a wet gas, and forming the silicon oxide film to a desired thickness by an oxidation method using a wet gas; .

In the method for forming a silicon oxide film according to the first aspect of the present invention, the ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer depends on the temperature of the silicon layer. Preferably, the temperature is such that the bond is not broken. In this case, the temperature at which silicon atoms do not desorb from the surface of the silicon layer is preferably a temperature at which Si—H bonds on the surface of the silicon layer are not broken or a temperature at which Si—F bonds on the surface of the silicon layer are not broken. When a silicon semiconductor substrate having a plane orientation of (100) is used, most of the hydrogen atoms on the surface of the silicon semiconductor substrate are bonded one by one to each of two bonds of silicon atoms, and the H-Si-H It has a termination structure. However, the portion where the surface state of the silicon semiconductor substrate is broken (for example, the step formation portion) is provided with one of the silicon atoms.
Termination structure in which a hydrogen atom is bonded to only one bond,
Alternatively, there is a terminal structure in which a hydrogen atom is bonded to each of the three bonds of a silicon atom. Usually, the remaining bonds of silicon atoms are bonded to silicon atoms inside the crystal. The expression “Si—H bond” in this specification refers to a terminal structure in which a hydrogen atom is bonded to each of two silicon atoms, and a hydrogen atom is bonded to only one silicon atom. The terminating structure in a state in which a hydrogen atom is bonded to each of the three bonding atoms of a silicon atom, or the terminating structure in a state in which a hydrogen atom is bonded to each of three bonding hands of a silicon atom is included. The temperature of the atmosphere when the formation of the silicon oxide film is started on the surface of the silicon layer is more specifically at a temperature at which the wet gas does not dew on the surface of the silicon layer, and is preferably 2 or more.
It is desirable that the temperature be not less than 00 ° C, more preferably not less than 300 ° C, from the viewpoint of throughput.

The second object of the present invention for achieving the above object.
In the method for forming a silicon oxide film according to the above aspect, the temperature is not lower than the temperature at which the wet gas does not condense on the surface of the silicon layer and is not higher than 500 ° C., preferably not higher than 450 ° C., and more preferably not higher than 400 ° C.
At an atmosphere temperature of not more than ゜ C, formation of a silicon oxide film is started on the surface of the silicon layer by an oxidation method using a wet gas, and the silicon oxide film is oxidized using a wet gas until a desired thickness is obtained. Is formed.

In the method for forming a silicon oxide film according to the first or second aspect of the present invention, the oxidation method using a wet gas includes a pyrogenic oxidation method, an oxidation method using water vapor generated by heating pure water, Further, it is preferable to use at least one oxidation method among the oxidation methods using water vapor generated by bubbling heated pure water with an oxygen gas or an inert gas. Since the silicon oxide film is formed by an oxidation method using a wet gas, a silicon oxide film having excellent time-dependent dielectric breakdown (TDDB) characteristics can be obtained. In the oxidation method using a wet gas, the wet gas may be diluted with an inert gas such as a nitrogen gas, an argon gas, and a helium gas.

In the method for forming a silicon oxide film according to the first or second aspect of the present invention, the atmosphere temperature at the time when the formation of the silicon oxide film having a desired thickness is completed is changed by setting the silicon oxide film on the surface of the silicon layer. The temperature may be higher than the ambient temperature at the start of film formation. The ambient temperature when the formation of the silicon oxide film having a desired thickness is completed is 60
The temperature may be 0 to 1200 ° C., preferably 700 to 1000 ° C., more preferably 750 to 900 ° C., but is not limited to such a value.

In order to further improve the characteristics of the formed silicon oxide film, in the method of forming a silicon oxide film according to the first or second aspect of the present invention, a silicon oxide film having a desired thickness is formed. After completion, it is preferable to perform a heat treatment on the formed silicon oxide film.

In this case, it is desirable that the atmosphere for the heat treatment be an inert gas atmosphere containing a halogen element.
By subjecting the silicon oxide film to a heat treatment in an inert gas atmosphere containing a halogen element, a silicon oxide film having excellent time-zero dielectric breakdown (TZDB) characteristics and temporal dielectric breakdown (TDDB) characteristics can be obtained. Examples of the inert gas in the heat treatment include a nitrogen gas, an argon gas, and a helium gas. In addition, examples of the halogen element include chlorine, bromine, and fluorine, and among them, chlorine is preferable. Examples of the form of the halogen element contained in the inert gas include hydrogen chloride (HCl), CCl ₄ , C ₂ HCl ₃ , Cl ₂ , and HB.
r and NF ₃ . The content of the halogen element in the inert gas is 0.001 to 10% by volume, preferably 0.005 to 10% by volume, based on the form of the molecule or compound.
It is 10% by volume, more preferably 0.02 to 10% by volume. For example, when using hydrogen chloride gas, the content of hydrogen chloride gas in the inert gas is preferably 0.02 to 10% by volume.

In the method of forming a silicon oxide film according to the first or second aspect of the present invention, the heat treatment may be a single-wafer treatment, but is preferably a furnace annealing treatment. The ambient temperature of the heat treatment is 700 to 120
0 ° C, preferably 700-1000 ° C, more preferably 700-950 ° C. When the heat treatment is furnace annealing, the heat treatment time is 5 to 60 minutes, preferably 10 to 40 minutes, and more preferably 20 to 30 minutes. On the other hand, when the heat treatment is a single-wafer treatment, the heat treatment time is preferably 1 to 10 minutes.

In the method of forming a silicon oxide film according to the first or second aspect of the present invention, the temperature of the heat treatment of the formed silicon oxide film is controlled by adjusting the ambient temperature at which the silicon oxide film having a desired thickness is formed. It is desirable that the temperature be higher than the ambient temperature at the time of completion. In this case, after the formation of the silicon oxide film having a desired thickness is completed, the atmosphere may be switched to an inert gas atmosphere, and then the temperature may be increased to the ambient temperature for performing the heat treatment. After switching to the contained inert gas atmosphere, it is preferable to raise the temperature to the ambient temperature for performing the heat treatment. here,
Examples of the inert gas include a nitrogen gas, an argon gas, and a helium gas. Examples of the form of the halogen element contained in the inert gas include hydrogen chloride (HCl), CCl ₄ , C ₂ HCl ₃ , Cl ₂ , and HB.
r and NF ₃ . The content of the halogen element in the inert gas is 0.001 to 10% by volume, preferably 0.005 to 10% by volume, based on the form of the molecule or compound.
It is 10% by volume, more preferably 0.02 to 10% by volume. For example, when using hydrogen chloride gas, the content of hydrogen chloride gas in the inert gas is preferably 0.02 to 10% by volume.

The heat treatment may be performed in a state in which the atmosphere of an inert gas containing a halogen element is reduced in pressure from atmospheric pressure.

After the heat treatment, the silicon oxide film may be nitrided. In this case, the nitriding treatment is performed with N ₂ O gas, NO
It is desirable to carry out in an atmosphere of gas and NO ₂ gas, and it is particularly desirable to carry out in an atmosphere of N ₂ O gas. Alternatively, it is preferable to perform the nitriding treatment in an atmosphere of NH ₃ gas, N ₂ H ₄ , and hydrazine derivative, and then perform the annealing treatment in an atmosphere of N ₂ O gas and O ₂ . 700 nitriding
The heating is preferably performed at a temperature of from 1200 to 1200 ° C., preferably from 800 to 1150 ° C., and more preferably from 900 to 1100 ° C. In this case, it is preferable to heat the silicon layer by infrared irradiation or furnace annealing.

Alternatively, the atmosphere for the heat treatment may be a nitrogen-based gas atmosphere. Here, as nitrogen-based gas,
Examples include N ₂ , NH ₃ , N ₂ O, NO ₂ , and NO.

In a preferred embodiment of the method for forming a silicon oxide film according to the first aspect of the present invention, the method is carried out at an ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer.
After starting the formation of a silicon oxide film on the surface of the silicon layer by an oxidation method using a wet gas, the silicon oxide film is kept at a temperature within an atmosphere temperature range in which silicon atoms are not desorbed from the surface of the silicon layer for a predetermined period. First to form a film
A silicon oxide film forming process and an oxidation method using a wet gas at an ambient temperature higher than an ambient temperature range in which silicon atoms are not desorbed from the surface of the silicon layer until the silicon oxide film reaches a desired thickness. The method may further include a second silicon oxide film forming step.

Also in this preferred embodiment of the present invention, the ambient temperature at which silicon atoms do not desorb from the surface of the silicon layer is a temperature at which the bond between the atoms terminating the surface of the silicon layer and the silicon atoms is not broken. Is preferred. In this case, the temperature at which silicon atoms do not desorb from the surface of the silicon layer is the temperature at which Si—H bonds on the surface of the silicon layer are not broken, or the temperature at which Si—F
Preferably, the temperature is such that the bond is not broken. The ambient temperature at the start of the formation of the silicon oxide film on the surface of the silicon layer is more specifically a temperature at which the wet gas does not condense on the surface of the silicon layer, preferably at least 200 ° C.
More preferably, the temperature is set to 300 ° C. or more from the viewpoint of throughput. Further, the oxidation method using a wet gas in the first silicon oxide film forming step, the second silicon oxide film forming step, or the first silicon oxide film forming step and the second silicon oxide film forming step is performed by pyrolysis. At least one of the following: a genic oxidation method, an oxidation method using water vapor generated by heating pure water, and an oxidation method using water vapor generated by bubbling heated pure water with an oxygen gas or an inert gas. Is preferred. Since the silicon oxide film is formed by an oxidation method using a wet gas, a silicon oxide film having excellent time-dependent dielectric breakdown (TDDB) characteristics can be obtained. Here, the same oxidation method or different oxidation methods may be used in the first silicon oxide film forming step and the second silicon oxide film forming step. The wet gas in the first silicon oxide film forming step, the second silicon oxide film forming step, or the first silicon oxide film forming step and the second silicon oxide film forming step may be nitrogen gas, argon gas, helium gas. May be diluted with an inert gas such as

Incidentally, the first silicon oxide film forming step, the second
The halogen gas may be contained in the wet gas in the silicon oxide film forming step, or in the first silicon oxide film forming step and the second silicon oxide film forming step. As a result, a silicon oxide film having excellent time zero dielectric breakdown (TZDB) characteristics and temporal dielectric breakdown (TDDB) characteristics can be obtained. In addition, chlorine, as a halogen element,
Bromine and fluorine can be mentioned, and among them, chlorine is desirable. Examples of the form of the halogen element contained in the wet gas include hydrogen chloride (HCl), C
Cl ₄ , C ₂ HCl ₃ , Cl ₂ , HBr and NF ₃ can be mentioned. The content of the halogen element in the wet gas is 0.001 to 10% by volume, preferably 0.005 to 10% by volume, more preferably 0.02 to 10% by volume, based on the form of the molecule or the compound. . For example, when hydrogen chloride gas is used, the content of hydrogen chloride gas in the wet gas is 0.1%.
Desirably, the content is 02 to 10% by volume.

In a preferred embodiment of the present invention, the second
Forming temperature of the silicon oxide film in the silicon oxide film forming step of 600 to 1200 ° C., preferably 700 ° C.
It is desirable that the temperature is in the range of 750 to 1000 ° C, more preferably 750 to 900 ° C.

In a method of forming a silicon oxide film according to a preferred embodiment of the present invention, a silicon oxide film forming apparatus having one processing chamber for forming a silicon oxide film is used to form a first silicon oxide film. The step and the second silicon oxide film forming step can be performed in the treatment chamber.
Note that such an embodiment is referred to as a first preferred embodiment of the present invention. In this case, it is preferable that the first silicon oxide film forming step and the second silicon oxide film forming step are performed in a batch system, and such an embodiment is referred to as a preferable 1A embodiment of the present invention.

Alternatively, in a first preferred embodiment of the present invention, a silicon layer disposed outside the processing chamber and substantially parallel to the surface of the silicon layer is heated. And a first silicon oxide film forming step and a second silicon oxide film forming step can be performed in a single-wafer manner. Such an embodiment is referred to as a preferred 1B embodiment of the present invention.

In the first preferred embodiment of the present invention, it is preferable to include a temperature raising step between the first silicon oxide film forming step and the second silicon oxide film forming step.
In this case, it is desirable that the atmosphere in the temperature raising step be an inert gas atmosphere or a reduced pressure atmosphere, or an oxidizing atmosphere containing a wet gas. Here, examples of the inert gas include a nitrogen gas, an argon gas, and a helium gas. Note that the inert gas or the wet gas in the atmosphere in the temperature raising step may contain a halogen element. Thereby, the characteristics of the silicon oxide film formed in the first silicon oxide film forming step can be further improved. That is, silicon dangling bonds (Si.) And SiOH, which are defects that can be generated in the first silicon oxide film forming step, react with the halogen element in the temperature raising step, and the silicon dangling bonds are terminated or a dehydration reaction occurs. In addition, these defects, which are reliability deterioration factors, are eliminated. In particular, elimination of these defects is effective for the initial silicon oxide film formed in the first silicon oxide film forming step. Examples of the halogen element include chlorine, bromine, and fluorine, and among them, chlorine is preferable.
Examples of the form of the halogen element contained in the inert gas or the wet gas include hydrogen chloride (HCl), CC
_{l 4, C 2 HCl 3,} Cl 2, HBr, may be mentioned NF _3. The content of the halogen element in the inert gas or wet gas is based on the form of the molecule or compound,
0.001 to 10% by volume, preferably 0.005 to 10%
%, More preferably 0.02 to 10% by volume.
For example, when hydrogen chloride gas is used, the content of hydrogen chloride gas in the inert gas or wet gas is desirably 0.02 to 10% by volume. The atmosphere in the temperature raising step may be an oxidizing atmosphere containing a wet gas diluted with an inert gas.

Alternatively, in a preferred embodiment of the present invention, a first processing chamber and a second processing chamber for forming a silicon oxide film, and a first processing chamber and a second processing chamber are formed. A first silicon oxide film forming step is performed in a first processing chamber using a silicon oxide film forming apparatus provided with a transfer path connecting the first and second silicon oxide films. , And then a second silicon oxide film forming step can be performed in the second processing chamber. Note that such an embodiment is referred to as a preferred second embodiment of the present invention.

In a preferred second embodiment of the present invention, transferring the silicon layer from the first processing chamber to the second processing chamber via a transfer path without exposing the silicon layer to the atmosphere includes the step of forming the silicon oxide layer. It is preferable from the viewpoint of preventing the occurrence of contamination on the surface of the film. Note that, specifically, the atmosphere in the transfer path during the transfer of the silicon layer is preferably an inert gas atmosphere or a reduced pressure atmosphere. Here, examples of the inert gas include a nitrogen gas, an argon gas, and a helium gas. In this case, the atmosphere temperature in the transfer path when the silicon layer is transferred from the first processing chamber to the second processing chamber via the transfer path may be, for example, room temperature (normal temperature). It is preferable that the temperature be substantially equal to the ambient temperature in the first processing chamber when the oxide film is formed, from the viewpoint of improving the throughput.

In the second preferred embodiment of the present invention, the first silicon oxide film forming step and the second silicon oxide film forming step can be performed by a batch method. Alternatively, the first silicon oxide film forming step can be performed by a single wafer type, and the second silicon oxide film forming step can be performed by a batch type. Further, the first silicon oxide film forming step and the second silicon oxide film forming step can be performed in a single-wafer manner.

In a preferred second embodiment of the present invention, a shutter is provided between a portion of the transport path communicating with the first processing chamber and a portion of the transport path communicating with the second processing chamber. A silicon oxide film forming apparatus can be used.

In a preferred embodiment of the present invention, it is desirable that the formed silicon oxide film is subjected to a heat treatment after the completion of the second silicon oxide film forming step. This heat treatment can be the same as the heat treatment described in the method for forming a silicon oxide film according to the first or second embodiment of the present invention, and thus detailed description is omitted. Note that the second silicon oxide film forming step and the heat treatment may be performed in the same processing chamber or may be performed in different processing chambers. Preferred treatment methods and heat treatment methods in the first silicon oxide film formation step and the second silicon oxide film formation step are exemplified in Table 1 below, but are not limited thereto.

[0044]

[Table 1] First silicon Second silicon Heat treatment Oxide film formation process Oxide film formation process Batch system Batch system Batch system Single wafer system Batch system Batch system Single wafer system Single wafer system Single wafer system Single wafer system Single wafer system Batch formula

In a preferred embodiment of the present invention, the final thickness of the silicon oxide film after the second silicon oxide film forming step may be a predetermined thickness required for the semiconductor device. On the other hand, the thickness of the silicon oxide film after the first silicon oxide film forming step is preferably as thin as possible. However, in most cases, the plane orientation of a silicon semiconductor substrate currently used for manufacturing a semiconductor device is (10
0), and no matter how the surface of the silicon semiconductor substrate is smoothed, a step called a step is always formed on the surface of the (100) silicon semiconductor substrate. This step is typically for one layer of silicon atoms, but in some cases 2-3
A step of the layer may be formed. Therefore, the thickness of the silicon oxide film after the first silicon oxide film forming step is preferably 1 nm or more when a (100) silicon semiconductor substrate is used as the silicon layer, but is not limited thereto. Absent.

In the method for forming a silicon oxide film according to the first aspect of the present invention including the preferred embodiments of the present invention, or the method for forming a silicon oxide film according to the second aspect of the present invention, The atmosphere before the film is formed, in order to suppress the formation of an undesired silicon oxide film before the formation of the silicon oxide film based on the wet gas, nitrogen gas, argon gas, an inert gas atmosphere such as helium gas, Alternatively, a reduced pressure atmosphere is desirable.

In the method for forming a silicon oxide film according to the first or second aspect of the present invention, the temperature of the atmosphere when the formation of the silicon oxide film having a desired thickness is completed is changed from the surface of the silicon layer to the silicon atom. The temperature may be within an ambient temperature range in which is not desorbed, or may be 500 ° C. or less, preferably 450 ° C. or less. Note that such an embodiment is referred to as a preferred third embodiment of the present invention. In the method for forming a silicon oxide film according to the third preferred embodiment of the present invention, the temperature of the atmosphere when starting the formation of the silicon oxide film on the surface of the silicon layer and the formation of the silicon oxide film having a desired thickness are reduced. The temperature of the atmosphere when the formation of the silicon oxide film is completed may be the same as the temperature of the atmosphere when the formation of the silicon oxide film on the surface of the silicon layer is started. Or higher temperature. In the latter case, the ambient temperature may be increased stepwise or continuously.

In the method for forming a silicon oxide film according to the third preferred embodiment of the present invention, after the formation of the silicon oxide film having a desired thickness is completed, the formed silicon oxide film is subjected to a heat treatment. preferable. The atmosphere for the heat treatment is preferably an inert gas atmosphere containing a halogen element, more preferably the halogen element is chlorine, and chlorine is in the form of hydrogen chloride (HCl). The concentration of hydrogen chloride contained is 0.0
More preferably, it is 2 to 10% by volume. The heat treatment is preferably performed at a temperature of 700 to 950 ° C., and more preferably, the heat treatment is a furnace annealing treatment. Note that this heat treatment can be the same as the heat treatment described in the method for forming a silicon oxide film according to the first or second aspect of the present invention described above, and a detailed description thereof will be omitted.

Usually, before forming a silicon oxide film on a silicon layer, the silicon layer is washed with an aqueous solution of NH ₄ OH / H ₂ O ₂ ,
The surface of the silicon layer is cleaned by RCA cleaning in which the surface is cleaned with l / H ₂ O ₂ aqueous solution, fine particles and metal impurities are removed from the surface, and then the surface of the silicon layer is cleaned with a hydrofluoric acid aqueous solution and pure water. . However, after that, when the silicon layer is exposed to the atmosphere, the surface of the silicon layer is contaminated, moisture and organic substances adhere to the surface of the silicon layer, or Si atoms on the surface of the silicon layer bond with hydroxyl groups (OH). (For example, the document "Highly-reliable Gate"
Oxide Formation for Giga-Scale LSIs by using Clos
ed Wet Cleaning System and Wet Oxidation with Ultr
a-Dry Unloading ", J. Yugami, et al., International
Electron Device Meeting Technical Digest 95, pp 8
55-858). In such a case, when the formation of the silicon oxide film is started as it is, moisture, an organic substance, or Si-OH is taken into the formed silicon oxide film, and the characteristics of the formed silicon oxide film deteriorate or It can cause the generation of defective portions. In addition, a defect part is a silicon dangling bond (Si.) Or Si-H
A portion of the silicon oxide film containing a defect such as a bond, or a Si-O-Si bond in which a Si-O-Si bond is compressed by stress or a Si-O-Si bond has a large angle or a bulk silicon oxide film It means a portion of the silicon oxide film including a Si-O-Si bond, which is different from the bond angle. Therefore, in order to avoid the occurrence of such a problem, a preferred embodiment of the present invention includes a step of cleaning the surface of the silicon layer before the step of forming the first silicon oxide film. Without exposing the layer to the atmosphere (that is, for example, the atmosphere from the cleaning of the silicon layer surface to the start of the first silicon oxide film forming step is an inert gas atmosphere or a vacuum atmosphere).
It is preferable to carry out the silicon oxide film forming step.
Alternatively, the method for forming a silicon oxide film according to the first or second aspect of the present invention includes a step of cleaning the surface of the silicon layer before forming the silicon oxide film,
Without exposing the silicon layer after surface cleaning to the atmosphere (ie,
For example, the atmosphere from the cleaning of the surface of the silicon layer to the start of the formation of the silicon oxide film is an inert gas atmosphere or a vacuum atmosphere), and it is preferable to form the silicon oxide film. As a result, a silicon oxide film can be formed on a silicon layer having a surface that is mostly terminated with hydrogen and a very small portion is terminated with fluorine, and the characteristics of the formed silicon oxide film are deteriorated or defects are generated. Can be prevented.

FIGS. 1 to 11 schematically show an ambient temperature profile in the method for forming a silicon oxide film of the present invention. In the figure, the lower limit of the ambient temperature when starting the formation of the silicon oxide film on the surface of the silicon layer indicated by T _1, T ₂ the upper limit of ambient temperature silicon atoms from the surface of the silicon layer is not eliminated Indicated by Moreover, the ambient temperature or the ambient temperature of the second silicon oxide film forming process when the formation of the desired thickness silicon oxide film is completed shown at T _3, indicating the ambient temperature in the heat treatment at T _4. In the figure, the solid line indicates the state in which the silicon oxide film is formed, and the dashed line indicates the process of raising the ambient temperature to the ambient temperature at which the formation of the silicon oxide film on the surface of the silicon layer is started, or It shows a process of lowering the ambient temperature to room temperature after completion of the film formation, or a process of raising the ambient temperature from the transport step to the ambient temperature in the second silicon oxide film forming step. Further, a dotted line indicates a transfer step in the transfer path, and a double line indicates a heat treatment step. The atmosphere temperature profile shown by the solid line in the temperature rise process indicates that the silicon oxide film is also formed in the temperature rise process, and the temperature rise process in the atmosphere temperature profile shown by the chain line in the temperature rise process. Indicates that no silicon oxide film is formed. In the figure, "RT" means room temperature (normal temperature).

In the example of the ambient temperature profile shown in FIGS. 1A and 1B, at an ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer, or when a wet gas is applied to the surface of the silicon layer. Above non-condensing temperature 5
The formation of a silicon oxide film on the surface of the silicon layer is started by an oxidation method using a wet gas at an atmosphere temperature of 00 ° C. or less. And by the oxidation method using wet gas,
A silicon oxide film is formed until a desired thickness is obtained. When the formation of the silicon oxide film having a desired thickness is completed, the ambient temperature is set at the temperature at which the formation of the silicon oxide film is started on the surface of the silicon layer. Whether the temperature is the same ((A) in FIG. 1)
Or within an ambient temperature range higher than the ambient temperature at which the formation of the silicon oxide film is started on the surface of the silicon layer but at which silicon atoms are not desorbed from the surface of the silicon layer, or 500 ° C. or lower. (See FIG. 1B).

In the example of the ambient temperature profile shown in FIGS. 2A and 2B, at an ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer, or when a wet gas is applied to the surface of the silicon layer. Above non-condensing temperature 5
The formation of a silicon oxide film on the surface of the silicon layer is started by an oxidation method using a wet gas at an atmosphere temperature of 00 ° C. or less. And by the oxidation method using wet gas,
The silicon oxide film is formed until the silicon oxide film has a desired thickness. When the formation of the silicon oxide film having the desired thickness is completed, the ambient temperature (T ₃ ) starts forming the silicon oxide film on the surface of the silicon layer. The temperature is higher than the ambient temperature (T _{1 to} T ₂ ) at which the silicon atoms are removed from the surface of the silicon layer. Note that, in the example of the ambient temperature profile shown in FIG. 2A, the heating rate is constant. On the other hand, in the example of the ambient temperature profile shown in FIG. 2B, the heating rate is changed. It should be noted that the change pattern of the heating rate is an example and is not limited to FIG.

The examples of the ambient temperature profiles shown in FIGS. 3 to 7 relate to the first preferred embodiment of the present invention, and
Through the silicon oxide film forming step, the temperature raising step, and the second silicon oxide film forming step, a silicon oxide film is formed. In the example shown in FIGS. 3A and 3B, the ambient temperature in the first silicon oxide film forming step and the second silicon oxide film forming step is constant. In the example shown in FIGS. 4A and 4B, the ambient temperature in the first silicon oxide film forming step is changed, but the ambient temperature in the second silicon oxide film forming step is constant. . In the example shown in FIGS. 5A and 5B, the ambient temperature in the first silicon oxide film forming step is constant, but the ambient temperature in the second silicon oxide film forming step is changed. . In the examples shown in FIGS. 6A and 6B, the ambient temperature in the first silicon oxide film forming step and the second silicon oxide film forming step is changed. The heating rate in the heating step may be constant or may be changed. Also,
When changing the ambient temperature in the first silicon oxide film forming step and / or the second silicon oxide film forming step, the rate of change may be constant or the rate of change may be different. Alternatively, an ambient temperature profile as shown in FIG. 7 can be used. Note that, in the example of the ambient temperature profile shown in FIG. 7A, the heating rate is constant. On the other hand, in the example of the ambient temperature profile shown in FIG. 7B, the heating rate is changed. In the examples shown in FIGS. 3A, 4A, 5A, and 6A, the heating step is performed in an inert gas atmosphere. No silicon oxide film is formed. On the other hand, in the examples shown in FIGS. 3 (B), 4 (B), 5 (B) and 6 (B), the temperature raising step is performed in an oxidizing atmosphere containing a wet gas, In the process, a silicon oxide film is formed.

The examples of the ambient temperature profiles shown in FIGS. 8 to 11 relate to the second preferred embodiment of the present invention.
A silicon oxide film is formed in the first silicon oxide film forming step and the second silicon oxide film forming step. In the examples shown in FIGS. 8A and 8B, the ambient temperature in the first silicon oxide film forming step and the second silicon oxide film forming step is constant. In the examples shown in FIGS. 9A and 9B, the ambient temperature in the first silicon oxide film forming step is changed, but the ambient temperature in the second silicon oxide film forming step is constant. . In the examples shown in FIGS. 10A and 10B,
The ambient temperature in the first silicon oxide film forming step is constant, but the ambient temperature in the second silicon oxide film forming step is changed. (A) and (B) of FIG.
In the example shown in (1), the ambient temperature in the first silicon oxide film forming step and the second silicon oxide film forming step is changed. 8A, FIG. 9A,
In the example shown in FIGS. 10A and 11A, the ambient temperature in the transport path in the transport step is, for example, room temperature (normal temperature). On the other hand, in the examples shown in FIG. 8B, FIG. 9B, FIG. 10B and FIG. The ambient temperature in the first processing chamber in the first silicon oxide film forming step is substantially equal to the ambient temperature.

In the method for forming a silicon oxide film according to the first or second aspect of the present invention, the term “silicon layer” means not only a substrate itself such as a silicon semiconductor substrate but also an epitaxial silicon layer ( (Including an epitaxial silicon layer formed by a selective epitaxial growth method), a polycrystalline silicon layer, or an amorphous silicon layer, a silicon layer in an SOI structure manufactured based on a so-called bonding method or a SIMOX method, Means a silicon layer on which a silicon oxide film is to be formed, such as a semiconductor element or a component of a semiconductor element formed on a layer of the same. The method for manufacturing the silicon semiconductor substrate is a CZ method,
Any method such as an MCZ method, a DLCZ method, and an FZ method may be used, or a method in which crystal defects are removed by performing a high-temperature hydrogen annealing treatment in advance.

The method of forming a silicon oxide film of the present invention includes, for example, formation of a gate oxide film of a MOS transistor, formation of an interlayer insulating film or an element isolation region, formation of a gate oxide film of a top gate or bottom gate thin film transistor, flash memory For example, the present invention can be applied to formation of a silicon oxide film in various semiconductor devices, such as formation of a tunnel oxide film.

Alternatively, in the method of forming a silicon oxide film according to the present invention, not only is the silicon oxide film a gate oxide film, but also the silicon layer is formed of a silicon semiconductor substrate, and the silicon oxide film is formed of a silicon semiconductor substrate. May be an oxide film formed on the silicon semiconductor substrate before the formation of the gate oxide film. In the latter case, an oxide film formed on the silicon semiconductor substrate before the gate oxide film is formed on the surface of the silicon semiconductor substrate is replaced with an oxide film for forming an element isolation region (that is, an element isolation region having a LOCOS structure or a trench structure). In the process, an oxide film as a base for depositing a silicon nitride film can be used, or a sacrificial oxide film can be used. The element isolation region has a LOCOS structure,
Alternatively, it has a trench structure, or
A form having an S structure and a trench structure can be adopted.

In the method of forming a silicon oxide film according to the first aspect of the present invention, an oxidation method using a wet gas is performed while maintaining an atmosphere at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer. The formation of a silicon oxide film on the surface of the silicon layer is started. In addition, the method for forming a silicon oxide film according to the second aspect of the present invention is characterized in that the silicon oxide film is formed by an oxidation method using a wet gas at an ambient temperature of 500 ° C. or higher and a temperature at which the wet gas does not dew on the surface of the silicon layer. The formation of a silicon oxide film on the surface of the layer is started. By setting the ambient temperature at the start of the formation of the silicon oxide film to such a temperature, it is possible to prevent the surface of the silicon layer from being uneven (rough). The oxidation of silicon atoms starts from the silicon atoms inside one layer, not from the outermost surface of the silicon layer. In other words, starting from a so-called back bond, a so-called layer-by-layer (Layer-By-Layer)
Oxidation. Accordingly, since the smoothness of the interface between the silicon layer and the silicon oxide film is maintained at the atomic level, the characteristics of the silicon oxide film finally formed are excellent. Moreover, since a silicon oxide film is formed on the surface of the silicon layer by an oxidation method using a wet gas, a dry oxide film is not included in the finally formed silicon oxide film,
A silicon oxide film having excellent characteristics can be formed.

In the method of forming a silicon oxide film according to the first or second aspect of the present invention, it takes a long time to form a silicon oxide film which sufficiently satisfies the characteristics required as a gate oxide film, for example. There are cases. In such a case, a preferred embodiment of the present invention may be adopted. In a preferred embodiment of the present invention, the second silicon oxide film forming step is performed in a state where a silicon oxide film which also functions as a protective film is already formed on the surface of the silicon layer. Even when the inside is a non-oxidizing atmosphere, no irregularities (roughness) occur on the surface of the silicon layer. Further, a silicon oxide film having excellent characteristics, which can sufficiently satisfy the characteristics required as a gate oxide film, can be formed in a short period of time.

In the method of forming a silicon oxide film according to the first preferred embodiment 1A of the present invention, a conventional silicon oxide film formation method of resistance heating in which a quartz processing chamber (oxidizing furnace) is held vertically. An apparatus can be used. By the way, when the silicon oxide film forming apparatus of the vertical type is used, for example, since the heater 14 is provided on the outer side of the silicon semiconductor substrate in the outer peripheral direction, the peripheral part of the silicon semiconductor substrate is always heated during the temperature rise. But the temperature is higher than in the center. As a result, when the silicon oxide film is formed even during the temperature rise, the thickness of the silicon oxide film tends to be larger at the peripheral portion of the silicon semiconductor substrate than at the central portion. In the method for forming a silicon oxide film according to the preferred embodiment 1B of the present invention, since the silicon layer is heated by the heating means disposed substantially parallel to the surface of the silicon layer, the temperature variation in the plane of the silicon layer Can be reduced. As a result, even when the silicon oxide film is formed during the temperature rise, it is possible to suppress occurrence of in-plane thickness variation of the formed silicon oxide film.

When a two-stage silicon oxide film is formed in one processing chamber, the atmosphere temperature in the processing chamber must be controlled over a wide range, and the atmosphere temperature in the processing chamber can be accurately controlled. Can be difficult to do. In addition, since it is necessary to raise the temperature of the atmosphere in the processing chamber, the throughput tends to decrease. In the second preferred embodiment of the present invention, since the silicon oxide film is formed in the first processing chamber and the second processing chamber, the temperature of the atmosphere in each processing chamber is maintained at a constant temperature within a predetermined narrow range. In addition, the atmosphere temperature in each processing chamber can be controlled more accurately, and the temperature stability in the processing chamber is excellent. Therefore, the thickness controllability of the silicon oxide film is excellent. In addition, as in the case where the formation of the silicon oxide film in two stages is performed in one processing chamber, the temperature ranges from the ambient temperature in the first silicon oxide film forming process to the ambient temperature in the second silicon oxide film forming process. Therefore, there is no need to change the ambient temperature, so that the throughput does not decrease.

In the method of forming a silicon oxide film according to the third preferred embodiment of the present invention, the temperature of the atmosphere when the formation of the silicon oxide film having a desired thickness is completed is set at 5 ° C.
Since the temperature is set to 00 ° C. or lower, the control range of the ambient temperature in the silicon oxide film forming apparatus can be narrowed, and the ambient temperature can be controlled with high accuracy.
There is no need to cool the processing chamber from a high temperature to a low temperature, and the time required for forming a silicon oxide film can be reduced. Although the formation rate of the silicon oxide film is reduced, the MOS LS having a design rule of 0.13 μm or less
The formation of a gate oxide film having a thickness of 3 nm or less used for I causes almost no problem in production. Since the atmosphere temperature in the processing chamber is lower than that in the related art, the speed at which the silicon layer is carried into and out of the processing chamber can be increased.
Therefore, the time required for forming the entire silicon oxide film is almost the same as the time required for forming the silicon oxide film according to the related art.

[0063]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

Example 1 Example 1 relates to a preferred 1A embodiment of the method for forming a silicon oxide film according to the first aspect of the present invention, and further relates to a silicon oxide film according to the second aspect of the present invention. The present invention relates to a method for forming an oxide film. In the first embodiment, a silicon oxide film forming apparatus having one processing chamber for forming a silicon oxide film is used, and a first silicon oxide film forming step and a second silicon oxide film forming step are performed in this processing chamber. Do with. Further, the first silicon oxide film forming step and the second silicon oxide film forming step are performed by a batch method. Also, the first silicon oxide film forming step and the second
A temperature raising step between the step of forming a silicon oxide film. Specifically, in Example 1, the vertical type silicon oxide film forming apparatus shown in FIG. 13 was used. Example 1
In, the silicon layer was composed of a silicon semiconductor substrate. The formed silicon oxide film functions as a gate oxide film. In Example 1, a pyrogenic oxidation method was employed as an oxidation method using a wet gas in the first silicon oxide film forming step and the second silicon oxide film forming step. Further, the atmosphere in the temperature raising step was an inert gas atmosphere. After a silicon oxide film is further formed in the second silicon oxide film forming step to a desired thickness, an inert gas atmosphere containing a halogen element (hydrogen chloride gas) is applied to the formed silicon oxide film. Heat treatment (furnace annealing treatment) in a nitrogen gas atmosphere containing
Hereinafter, a method of forming the silicon oxide film of the first embodiment will be described with reference to FIGS. FIG. 14 schematically shows an ambient temperature profile in the first embodiment.

[Step-100] First, an N-type silicon wafer doped with phosphorus and having a diameter of 8 inches (made by the CZ method)
LOC is formed on a silicon semiconductor substrate 40 by a known method.
An element isolation region 41 having an OS structure was formed, and then well ion implantation, channel stop ion implantation, and threshold adjustment ion implantation were performed. Note that the element isolation region may have a trench structure or a combination of a LOCOS structure and a trench structure. Thereafter, fine particles and metal impurities on the surface of the silicon semiconductor substrate 40 are removed by RCA cleaning, and then the surface of the silicon semiconductor substrate 40 is cleaned with a 0.1% aqueous hydrofluoric acid solution and pure water.
The surface of the silicon semiconductor substrate 40 was exposed (see FIG. 12A). The surface of the silicon semiconductor substrate 40 is mostly terminated with hydrogen, and a very small portion is terminated with fluorine.

[Step-110] Next, the plurality of silicon semiconductor substrates 40 were loaded into the substrate loading / unloading section 20 of the silicon oxide film forming apparatus shown in FIG. (See FIG. 15A). Note that nitrogen gas is introduced from the gas introduction unit 12 into the processing chamber 10, the inside of the processing chamber 10 is set to an inert gas atmosphere such as a nitrogen gas (a reduced pressure atmosphere may be used), and a heater is provided through the soaking tube 16. 14, the atmosphere temperature in the processing chamber 10 is set to 400 ° C.
Held. In this state, the shutter 15
Is closed.

[Step-120] Then, the substrate loading / unloading section 2
0, the door (not shown) is closed, and the gas introduction unit 21 is inserted into the substrate carry-in / out unit 20.
The nitrogen gas was introduced from the gas exhaust unit 22 and exhausted from the gas exhaust unit 22, and the inside of the substrate loading / unloading unit 20 was set to a nitrogen gas atmosphere. The oxygen gas concentration in the substrate loading / unloading section 20 is monitored, and if the oxygen gas concentration becomes, for example, 100 ppm or less, it is determined that the inside of the substrate loading / unloading section 20 has a sufficient nitrogen gas atmosphere. Thereafter, the shutter 15 is opened (see FIG. 15B), the elevator mechanism 23 is operated, and the quartz boat 24 is opened.
(Ascending speed: 250 mm / min), and the silicon semiconductor substrate 40 was carried into the processing chamber 10 having a double-tube structure made of quartz (see FIG. 16A). When the elevator mechanism 23 reaches the highest position, the base of the quartz boat 24 stops communication between the processing chamber 10 and the substrate loading / unloading section 20. The temperature of the atmosphere in the processing chamber 10 is
Since the temperature is maintained at 00 ° C., that is, the temperature of the processing chamber
Since the inside of 0 is held, it is possible to suppress the occurrence of roughness on the surface of the silicon semiconductor substrate 40.

[Step-130] Then, formation of a silicon oxide film on the surface of the silicon layer was started by an oxidation method using a wet gas at an ambient temperature at which silicon atoms were not desorbed from the surface of the silicon layer. Alternatively, the formation of a silicon oxide film on the surface of the silicon layer was started by an oxidation method using a wet gas at an ambient temperature of 500 ° C. or higher at a temperature at which the wet gas did not condense on the surface of the silicon layer. Then, at an ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer, the formation of a silicon oxide film on the surface of the silicon layer by an oxidation method using a wet gas is started. A first silicon oxide film forming step of forming a silicon oxide film while maintaining an atmosphere in an atmosphere temperature range where silicon atoms are not desorbed was performed. Specifically, while maintaining the ambient temperature at a temperature at which silicon atoms do not desorb from the surface of the silicon layer (the silicon semiconductor substrate 40 in the first embodiment) (specifically, in the first embodiment, The temperature was set to 400 ° C.), and a silicon oxide film 42 was formed on the surface of the silicon layer by an oxidation method using a wet gas. In the first embodiment, oxygen gas and hydrogen gas are supplied into the combustion chamber 30 via the pipes 32 and 33, and steam generated in the combustion chamber 30 is supplied to the pipe 3
1, processing chamber 1 via gas flow path 11 and gas introduction unit 12
Then, a silicon oxide film 42 having a thickness of 1.2 nm was formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method (see FIG. 16B). The thickness of the silicon oxide film is a thickness corresponding to several molecular layers of SiO ₂ , and is a thickness sufficient to function as a protective film even in consideration of steps on the surface of the silicon semiconductor substrate.

[Step-140] Thereafter, the introduction of the wet gas into the processing chamber 10 is stopped, and an inert gas (nitrogen gas) is introduced.
Is introduced into the processing chamber 10 through the pipe 32, the combustion chamber 30, the pipe 31, the gas flow path 11, and the gas introduction unit 12, and the atmosphere temperature in the processing chamber 10 of the silicon oxide film forming apparatus is reduced. The temperature was increased to 800 ° C. by the heater 14 via the heater 16 (see FIG. 17A). The heating rate was 10 ° C./min. Since a silicon oxide film which also functions as a protective film is already formed on the surface of the silicon layer in [Step-130], the surface of the silicon layer (silicon semiconductor substrate 40) is roughened in this [Step-140]. Does not occur.

[Step-150] The processing chamber 10 is heated to an ambient temperature (800 ° C. in the first embodiment) higher than the ambient temperature range in which silicon atoms are not desorbed from the surface of the silicon layer.
After the internal temperature of the inside was reached, a second silicon oxide film forming step of forming a silicon oxide film was further performed by an oxidation method using a wet gas while maintaining the atmosphere at this temperature. Specifically, oxygen gas and hydrogen gas are again supplied into the combustion chamber 30 via the pipes 32 and 33, and the steam generated in the combustion chamber 30 is supplied to the pipe 31, the gas flow path 11 and the gas introduction unit 12 again. Then, a silicon oxide film 42 having a total thickness of 4.0 nm was formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method (see FIG. 17B). The ambient temperature at which the formation of the silicon oxide film having a desired thickness is completed (800 ° C. in the first embodiment) is the same as the ambient temperature at which the formation of the silicon oxide film is started on the surface of the silicon layer. In Example 1, it is higher than 400 ° C.).

As described above, the formation of the silicon oxide film 42 on the surface of the silicon semiconductor substrate 40 is completed.
Thereafter, the interior of the processing chamber 10 may be set to an inert gas atmosphere such as nitrogen gas, the elevator mechanism 23 may be operated to lower the quartz boat 24, and then the door (not shown) may be opened to carry out the silicon semiconductor substrate 40. If it is intended to form a silicon oxide film having higher characteristics, it is preferable to perform a heat treatment described below on the silicon oxide film.

[Step-160] That is, after that, the processing chamber 1
The introduction of the wet gas to 0 was stopped, and the temperature of the atmosphere in the processing chamber 10 was raised to 850 ° C. by the heater 14 while introducing the nitrogen gas into the processing chamber 10 from the gas introduction unit 12.
Thereafter, nitrogen gas containing 0.1% by volume of hydrogen chloride gas was introduced into the processing chamber 10 from the gas introduction unit 12, and heat treatment was performed for 30 minutes.

[Step-170] Thus, the formation of the silicon oxide film 42 on the surface of the silicon semiconductor substrate 40 is completed (see FIG. 12B). Thereafter, the processing room 10
The interior was set to a nitrogen gas atmosphere, the elevator mechanism 23 was operated to lower the quartz boat 24, and then the silicon semiconductor substrate 40 was unloaded from the substrate loading / unloading section 20.

[Step-180] In the first embodiment, using the silicon semiconductor substrate on which the silicon oxide film is formed as described above, the silicon oxide film 4
A gate electrode 43 having a polycide structure made of polysilicon and tungsten silicide is formed on
A capacitor was manufactured (see FIG. 12C).

(Embodiment 2) Embodiment 2 is a modification of Embodiment 1. In Example 2, [Step-14] of Example 1 was used.
0], the introduction of the wet gas into the processing chamber 10 is not stopped, and the processing chamber 10 of the silicon oxide film forming apparatus is stopped.
The temperature of the atmosphere inside was raised to 800 ° C. by the heater 14 through the soaking tube 16. In the second embodiment, a silicon oxide film is formed also in the temperature raising step.
In the same step as [Step-130], a silicon oxide film having a thickness of 1.0 nm was formed. Other steps were the same as in Example 1. FIG. 18 schematically shows the ambient temperature profile in the second embodiment.

(Embodiment 3) Embodiment 3 is also a modification of Embodiment 1. In Example 3, a 10 μm-thick epitaxial silicon layer was formed on a silicon semiconductor substrate by a known method. Then, [Step-110] to [Step-18] of Example 1 are formed on the surface of the epitaxial silicon layer.
0], a silicon oxide film is formed based on the same process as
Further, a MOS capacitor was manufactured. The total thickness of the silicon oxide film was 4.0 nm. In the same step as [Step-130], a silicon oxide film having a thickness of 1.2 nm was formed.

Comparative Example 1 In Comparative Example 1, a silicon oxide film having a thickness of 4.0 nm was formed on the surface of a silicon semiconductor substrate based on a conventional method for forming a silicon oxide film. That is, based on [Step-10] to [Step-40],
A silicon oxide film was formed. In [Step-20], before opening the shutter 15, a nitrogen gas containing 0.5% by volume of oxygen gas is introduced into the processing chamber 10 from the gas introduction unit 12, and the inside of the processing chamber 10 is set at 0.1%. A nitrogen gas atmosphere (atmospheric temperature: 800 ° C.) containing 5% by volume of oxygen gas was used. The atmosphere temperature in the processing chamber 10 was set to 800 ° C., and a silicon oxide film was formed on the surface of the silicon semiconductor substrate by a pyrogenic oxidation method. From the silicon semiconductor substrate on which the silicon oxide film was formed,
Similarly to the above, a MOS capacitor was manufactured. Before the silicon oxide film was formed on the surface of the silicon semiconductor substrate by the pyrogenic oxidation method, the silicon semiconductor substrate was loaded into the processing chamber 10 in a nitrogen gas atmosphere containing 0.5% by volume of oxygen gas. A dry oxide film having a thickness of 2.3 nm was formed on the surface of the silicon semiconductor substrate.

Comparative Example 2 In Comparative Example 2, in the same step as [Step-130] of Example 1, the atmosphere was maintained at a temperature at which silicon atoms were not desorbed from the surface of the silicon semiconductor substrate. In Comparative Example 2, specifically, the atmosphere temperature was set to 400 ° C.). Instead of forming a silicon oxide film on the surface of the silicon layer by an oxidation method using a wet gas, 0.5% by volume of oxygen was used. A dry oxide film having a thickness of 1.2 nm was formed in a nitrogen gas atmosphere containing.
Other steps were the same as in Example 1.

Example 1, Example 2, Example 3, Comparative Example 1
In order to evaluate the long-term reliability of the silicon oxide film with respect to the MOS capacitor manufactured according to Comparative Example 2, a time-dependent dielectric breakdown (Time Dependent Dielectric Breakdown,
TDDB) characteristics were measured. This aging dielectric breakdown
This is a phenomenon in which the silicon oxide film does not break down at the moment when the current stress or the voltage stress is applied, but dielectric breakdown occurs in the silicon oxide film after a certain time has elapsed after the stress application.

The time-dependent dielectric breakdown (TDDB) characteristics were evaluated by the following method. Fifty MOS capacitors were formed on one silicon semiconductor substrate 40. The gate area of the MOS capacitor was set to 0.1 mm ² . Then, two silicon semiconductor substrates were used for the evaluation. A circuit schematically shown in FIG. 19 is made, and a constant current (J
= 0.1 A / cm ² ) A so-called Coulomb breakdown (Q _BD ) was measured by a constant current stress method applying a stress. Here, Q _BD is represented by the product of J (A / cm ² ) and the time t _BD until dielectric breakdown. FIG. 20, FIG.
FIG. 22 is a diagram showing a Weibull probability distribution of the relationship between the cumulative failure rate P and Q _BD . In FIG. 20, white circles indicate the evaluation results of the silicon oxide film obtained in Example 1, black triangles indicate the evaluation results of the silicon oxide film obtained in Comparative Example 1, and white square marks Shows the evaluation results of the silicon oxide film obtained in Comparative Example 2. 21 indicate the evaluation results of the silicon oxide film obtained in Example 2.
The mark “x” indicates the evaluation result of the silicon oxide film obtained by the same method as in Comparative Example 1. Further, black triangles in FIG. 22 show the evaluation results of the silicon oxide film obtained in Example 3,
The mark “x” indicates the evaluation result of the silicon oxide film obtained by the same method as in Comparative Example 1. As is clear from FIG.
In the silicon oxide film obtained in Example 1, the amount of injected charges until the dielectric breakdown was twice or more that of Comparative Example 1, indicating that the long-term reliability was improved. The long-term reliability of the silicon oxide film obtained in the third embodiment, that is, the long-term reliability of the silicon oxide film formed on the epitaxial silicon layer is higher than that of the silicon oxide film obtained in the first embodiment. , Is even better.

(Embodiment 4) Embodiment 4 is also a modification of Embodiment 1. In the same manner as in Example 1, except that the ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer in the first silicon oxide film forming step is set to 350 ° C. or 450 ° C.
A first silicon oxide film forming step was performed. For comparison, a silicon oxide film was formed at an ambient temperature of 550 ° C. in the first silicon oxide film forming step. Other steps were the same as in Example 1. Then, as in the first embodiment, one silicon semiconductor substrate 4
At 0, 50 MOS capacitors were produced. The black squares in FIG. 23 show the relationship between the Q _BD value of the MOS capacitors manufactured in Example 1 and Example 4 at a cumulative failure rate of 50% and the ambient temperature in the first silicon oxide film forming step. FIG. 23 also shows the relationship between the amount of desorbed hydrogen atoms from the surface of the silicon semiconductor substrate (arbitrary unit) and the ambient temperature in the first silicon oxide film forming step by white circles. FIG. 23 shows that when the ambient temperature in the first silicon oxide film forming step exceeds 500 ° C., the amount of desorbed hydrogen atoms sharply increases, and the value of Q _BD at 50% of the cumulative defect rate of the MOS capacitor. Is reduced to about the MOS capacitor manufactured by the conventional technology. For example, the Q _BD of the MOS capacitor obtained in Example 1 at a cumulative failure rate of 50% is about twice as large as that of Comparative Example 1. When the ambient temperature in the first silicon oxide film forming step is 350 ° C., Q _{BD at} a cumulative failure rate of 50% of the MOS capacitor is further improved.

(Embodiment 5) Embodiment 5 is also a modification of Embodiment 1. Example 5 differs from Example 1 in the ambient temperature profile in the first silicon oxide film forming step, the temperature raising step, and the second silicon oxide film forming step. FIG. 24 schematically shows the ambient temperature profile in Example 5.
Shown in Hereinafter, a method for forming the silicon oxide film of the fifth embodiment will be described.

[Step-500] First, an element isolation region and the like are formed on a silicon semiconductor substrate in the same manner as in Example 1, and then fine particles and metal impurities on the surface of the silicon semiconductor substrate are removed by RCA cleaning. Next, the surface of the silicon semiconductor substrate was washed with a 0.1% aqueous solution of hydrofluoric acid and pure water to expose the surface of the silicon semiconductor substrate.

[Step-510] Next, a plurality of silicon semiconductor substrates are loaded into the substrate loading / unloading section 20 of the silicon oxide film forming apparatus shown in FIG. FIG. 25A). In addition, nitrogen gas is introduced into the processing chamber 10 from the gas introduction unit 12 and
The inside of 0 was an inert gas atmosphere such as a nitrogen gas (a reduced pressure atmosphere may be used). In Example 5, the ambient temperature in the processing chamber 10 was room temperature.

[Step-520] Substrate carry-in / out section 2
After the loading of the silicon semiconductor substrate into the substrate loading / unloading unit 20 is completed, a door (not shown) is closed, nitrogen gas is introduced into the substrate loading / unloading unit 20 from the gas introduction unit 21, exhausted from the gas exhaust unit 22, and discharged into the substrate loading / unloading unit 20. Was set to a nitrogen gas atmosphere. The oxygen gas concentration in the substrate loading / unloading section 20 is monitored, and if the oxygen gas concentration becomes, for example, 100 ppm or less, it is determined that the inside of the substrate loading / unloading section 20 has a sufficient nitrogen gas atmosphere. Thereafter, the shutter 15 was opened, the elevator mechanism 23 was operated, the quartz boat 24 was raised, and the silicon semiconductor substrate was carried into the processing chamber 10 having a double-tube structure made of quartz (see FIG. 25B). The rising speed of the elevator mechanism 23 was set to 500 mm / min.

[Step-530] Next, the temperature of the atmosphere in the processing chamber 10 is reduced to 2 by the heater 14 through the heat equalizing tube 16.
The temperature was raised to 00 ° C (see FIG. 26A). After the ambient temperature in the processing chamber 10 is stabilized at 200 ° C., that is, the ambient temperature is set to a temperature at which silicon atoms do not desorb from the surface of the silicon layer (the silicon semiconductor substrate in the fifth embodiment). Specifically, after setting the ambient temperature to 200 ° C.), the formation of the silicon oxide film 42 on the surface of the silicon layer was started by an oxidation method using a wet gas. The concentration of 0.1% by volume in wet gas
Hydrogen chloride gas may be contained. In particular,
Steam generated in the combustion chamber 30 and, if desired, hydrogen chloride gas are introduced into the processing chamber 10 through the pipe 31, the gas flow path 11 and the gas introduction unit 12, and the silicon semiconductor is formed by a pyrogenic oxidation method. The formation of a silicon oxide film on the surface of the substrate was started. Thereafter, while forming a silicon oxide film, the ambient temperature in the processing chamber 10 was raised to 400 ° C. by the heater 14 through the soaking tube 16 (see FIG. 26B). Thereby, the thickness of 1 nm
A silicon oxide film of a degree was formed.

[Step-540] Thereafter, the introduction of the wet gas into the processing chamber 10 is stopped, and an inert gas (which may or may not contain a halogen element) is introduced into the gas introduction section 12.
The temperature of the atmosphere in the processing chamber 10 of the silicon oxide film forming apparatus was raised to 600 ° C. by the heater 14 through the heat equalizing tube 16 while being introduced into the processing chamber 10 from FIG.
(A)). Since a silicon oxide film which also functions as a protective film is already formed on the surface of the silicon layer in [Step-530], the surface of the silicon layer (silicon semiconductor substrate) is formed in this [Step-540]. No roughening occurs. While the introduction of the wet gas (which may or may not contain a halogen element) into the processing chamber 10 is continued, the temperature of the atmosphere in the processing chamber 10 of the silicon oxide film forming apparatus is increased by a heater through the soaking tube 16. 14, the temperature may be increased to an ambient temperature (600 ° C.) higher than the ambient temperature range in which silicon atoms are not desorbed from the surface of the silicon layer.

[Step-550] The processing chamber 10 is heated to 600 ° C.
After the temperature of the inside of the silicon layer was reached, while maintaining the atmosphere at this temperature, a silicon oxide film 42 was further formed on the surface of the silicon layer by an oxidation method using a wet gas (FIG. 27).
(B)). The wet gas may contain a hydrogen chloride gas having a concentration of 0.1% by volume. Specifically, steam generated in the combustion chamber 30 and, if desired, hydrogen chloride gas are introduced into the processing chamber 10 via the pipe 31, the gas passage 11 and the gas introduction unit 12, and the pyrogenic gas is introduced. A silicon oxide film having a total thickness of 3.5 nm was formed on the surface of the silicon semiconductor substrate by an oxidation method.

As described above, the formation of the silicon oxide film 42 on the surface of the silicon semiconductor substrate 40 is completed.
Thereafter, the interior of the processing chamber 10 may be set to an inert gas atmosphere such as nitrogen gas, the elevator mechanism 23 may be operated to lower the quartz boat 24, and then the door (not shown) may be opened to carry out the silicon semiconductor substrate 40. If it is intended to form a silicon oxide film having higher characteristics, it is preferable to perform a heat treatment described below on the silicon oxide film.

[Step-560] That is, after that, the processing chamber 1
The introduction of the wet gas to 0 was stopped, and the temperature of the atmosphere in the processing chamber 10 was raised to 850 ° C. by the heater 14 while introducing the nitrogen gas into the processing chamber 10 from the gas introduction unit 12.
Thereafter, nitrogen gas containing 0.1% by volume of hydrogen chloride gas was introduced into the processing chamber 10 from the gas introduction unit 12, and heat treatment was performed for 30 minutes.

[Step-570] Thus, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate is completed. Thereafter, the processing chamber 10 is set to a nitrogen gas atmosphere, the elevator mechanism 23 is operated, and the quartz boat 24 is lowered,
The door was opened, and then the silicon semiconductor substrate was unloaded from the substrate loading / unloading section 20.

(Embodiment 6) Embodiment 6 is also a modification of Embodiment 1. Embodiment 6 is different from Embodiment 1 in that the wet gas in the first silicon oxide film forming step and the second silicon oxide film forming step contains a halogen element (specifically, chlorine). It is in. Note that chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride gas contained in the wet gas was set to 0.1% by volume. Also in the sixth embodiment, FIG.
The vertical type silicon oxide film forming apparatus shown in FIG.
Also in Example 6, the silicon layer was formed from a silicon semiconductor substrate. The formed silicon oxide film functions as a gate oxide film. The atmosphere in the temperature raising step was an inert gas atmosphere. After a silicon oxide film is further formed in the second silicon oxide film forming step, the formed silicon oxide film is applied to an inert gas atmosphere containing a halogen element (a nitrogen gas atmosphere containing a hydrogen chloride gas). Heat treatment (furnace annealing) was performed. Hereinafter, a method for forming the silicon oxide film of the sixth embodiment will be described with reference to FIGS. The ambient temperature profile in Example 6 was the same as in FIG.

[Step-600] First, an element isolation region and the like are formed in a silicon semiconductor substrate in the same manner as in Example 1, and fine particles and metal impurities on the surface of the silicon semiconductor substrate are removed by RCA cleaning. Next, the surface of the silicon semiconductor substrate was washed with a 0.1% aqueous solution of hydrofluoric acid and pure water to expose the surface of the silicon semiconductor substrate.

[Step-610] Next, a plurality of silicon semiconductor substrates are loaded into the substrate loading / unloading section 20 of the silicon oxide film forming apparatus shown in FIG. 13 from a door (not shown) and placed on the quartz boat 24 ( FIG. 28A). In addition, nitrogen gas is introduced into the processing chamber 10 from the gas introduction unit 12 and
0 is an inert gas atmosphere such as a nitrogen gas atmosphere (a reduced pressure atmosphere may be used), and the heater 1
4, the atmosphere temperature in the processing chamber 10 was maintained at 400 ° C. In this state, the shutter 15 is closed.

[Step-620] Then, the substrate loading / unloading section 2
After the loading of the silicon semiconductor substrate into the substrate loading / unloading unit 20 is completed, a door (not shown) is closed, nitrogen gas is introduced into the substrate loading / unloading unit 20 from the gas introduction unit 21, exhausted from the gas exhaust unit 22, and discharged into the substrate loading / unloading unit 20. Was set to a nitrogen gas atmosphere. The oxygen gas concentration in the substrate loading / unloading section 20 is monitored, and if the oxygen gas concentration becomes, for example, 100 ppm or less, it is determined that the inside of the substrate loading / unloading section 20 has a sufficient nitrogen gas atmosphere. Thereafter, the shutter 15 is opened (see FIG. 28B),
The quartz boat 24 was raised by operating the elevator mechanism 23, and the silicon semiconductor substrate was carried into the processing chamber 10 having a double-tube structure made of quartz (see FIG. 29A). When the elevator mechanism 23 reaches the highest position, the quartz boat 24
No communication is established between the processing chamber 10 and the substrate loading / unloading section 20 by the base. The atmosphere temperature in the processing chamber 10 is set to the heater 1
4, the temperature is maintained at 400 ° C., so that it is possible to suppress the occurrence of roughness on the surface of the silicon semiconductor substrate.

[Step-630] Then, while maintaining the atmosphere at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer (the silicon semiconductor substrate in the sixth embodiment), specifically, in the sixth embodiment, Set the ambient temperature to 40
(Set at 0 ° C.), and a silicon oxide film was formed on the surface of the silicon layer by an oxidation method using a wet gas. The wet gas contains a hydrogen chloride gas having a concentration of 0.1% by volume. Specifically, steam generated in the combustion chamber 30,
And a hydrogen chloride gas are introduced into the processing chamber 10 through the pipe 31, the gas flow path 11, and the gas introduction unit 12, and a silicon oxide film having a thickness of about 1 nm is formed on the surface of the silicon semiconductor substrate by a pyrogenic oxidation method. (See FIG. 29B).

[Step-640] Thereafter, the introduction of the wet gas into the processing chamber 10 is stopped, and an inert gas made of, for example, nitrogen gas (which may or may not contain a halogen element) is introduced into the gas introduction section 12. The temperature of the atmosphere in the processing chamber 10 of the silicon oxide film forming apparatus was raised to 800 ° C. by the heater 14 through the heat equalizing tube 16 while being introduced into the processing chamber 10 from (FIG. 30A). . In addition, [Step-
[630] Since a silicon oxide film which also functions as a protective film is already formed on the surface of the silicon layer in [630], the surface of the silicon layer (silicon semiconductor substrate) may be roughened in this [Step-640]. There is no. Alternatively, while the introduction of the wet gas (which may or may not contain a halogen element) into the processing chamber 10 is continued, the atmospheric temperature in the processing chamber 10 of the silicon oxide film forming apparatus is set to The temperature may be increased by the heater 14 to an ambient temperature (for example, 800 ° C.) higher than the ambient temperature range in which silicon atoms are not desorbed from the surface of the silicon layer.

[Step-650] The processing chamber 10 is heated to 800 ° C.
After the temperature of the atmosphere was reached, a silicon oxide film was further formed by an oxidation method using, for example, a wet gas containing 0.1% by volume of hydrogen chloride gas while maintaining the atmosphere at this temperature. Specifically, water vapor and hydrogen chloride gas generated in the combustion chamber 30 are introduced into the processing chamber 10 through the pipe 31, the gas flow path 11, and the gas introduction unit 12, and the silicon semiconductor is formed by pyrogenic oxidation. A silicon oxide film having a total thickness of 4.0 nm was formed on the surface of the substrate (FIG. 30).
(B)).

Thus, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate is completed. Thereafter, the interior of the processing chamber 10 is set to an inert gas atmosphere such as nitrogen gas, and the elevator mechanism 23 is operated to move the quartz boat 24. After lowering, the door (not shown) may be opened and the silicon semiconductor substrate may be carried out. However, when a silicon oxide film having higher characteristics is intended, a heat treatment described below is applied to the silicon oxide film. Is preferred.

[Step-660] Thereafter, the introduction of the wet gas into the processing chamber 10 is stopped, and the nitrogen gas is introduced into the processing chamber 10 from the gas introduction unit 12 while the ambient temperature of the processing chamber 10 is controlled by the heater 14. The temperature was raised to 850 ° C. Thereafter, nitrogen gas containing 0.1% by volume of hydrogen chloride gas was introduced into the processing chamber 10 from the gas introduction unit 12, and heat treatment was performed for 30 minutes.

[Step-670] Thus, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate is completed. Thereafter, the processing chamber 10 is set to a nitrogen gas atmosphere, the elevator mechanism 23 is operated, and the quartz boat 24 is lowered,
The door (not shown) was opened, and then the silicon semiconductor substrate was unloaded from the substrate loading / unloading section 20.

Example 7 Example 7 relates to the preferred 1B mode of the method for forming a silicon oxide film according to the first aspect of the present invention, and further relates to the silicon aspect according to the second aspect of the present invention. The present invention relates to a method for forming an oxide film. In the seventh embodiment, the processing chamber is provided with heating means for heating the silicon layer, which is provided outside the processing chamber and substantially parallel to the surface of the silicon layer. The first silicon oxide film forming step and the second silicon oxide film forming step are performed in a single-wafer manner.

FIG. 31 is a schematic diagram showing an example of a horizontal silicon oxide film forming apparatus suitable for carrying out the seventh embodiment. This silicon oxide film forming apparatus includes a processing chamber 50 and a resistance heater 51 as heating means for heating the silicon layer. The processing chamber 50 is composed of a quartz furnace tube, and houses a silicon layer (specifically, for example, a silicon semiconductor substrate) therein to form a silicon oxide film on the silicon layer. The resistance heater 51 serving as a heating means is provided outside the processing chamber 50 and is provided substantially in parallel with the surface of the silicon layer. The silicon layer (for example, the silicon semiconductor substrate 40) is placed on the wafer table 52, and is passed through a gate valve 53 provided at one end of the processing chamber 50.
It is carried into and out of the processing chamber 50. The silicon oxide film forming apparatus further includes a gas introduction unit 54 for introducing water vapor and / or gas into the processing chamber 50, and a gas exhaust unit 55 for exhausting water vapor and / or gas from the processing chamber 50. . The temperature of the silicon layer (specifically, for example, a silicon semiconductor substrate) can be measured by a thermocouple (not shown). Note that, similarly to the first embodiment, the hydrogen gas supplied to the combustion chamber is mixed with the oxygen gas at a high temperature in the combustion chamber and burned to generate steam. The water vapor is introduced into the processing chamber 50 via the pipe and the gas introduction unit 54. Illustration of the combustion chamber and piping is omitted.

Alternatively, a horizontal silicon oxide film forming apparatus of the type schematically shown in FIG. 32 can be used.
In the horizontal silicon oxide film forming apparatus shown in FIG. 32, the heating means is composed of a plurality of lamps 51A that emit infrared light or visible light. The temperature of the silicon semiconductor substrate is measured by a pyrometer (not shown). Other structures can be basically the same as those of the silicon oxide film forming apparatus shown in FIG. 31, and therefore, detailed description is omitted.

Hereinafter, a method for forming the silicon oxide film of the seventh embodiment will be described. The atmosphere temperature profile in Example 7 was the same as that in FIG.

[Step-700] First, an element isolation region and the like are formed in a silicon semiconductor substrate in the same manner as in Embodiment 1, and fine particles and metal impurities on the surface of the silicon semiconductor substrate are removed by RCA cleaning. Next, the surface of the silicon semiconductor substrate was washed with a 0.1% aqueous solution of hydrofluoric acid and pure water to expose the surface of the silicon semiconductor substrate.

[Step-710] Next, the silicon semiconductor substrate 40 mounted on the wafer stage 52 is connected to the gate valve 5 of the silicon oxide film forming apparatus shown in FIG. 31 or FIG.
3 was opened and carried into the processing chamber 50, and then the gate valve 53 was closed. At this time, the atmosphere in the processing chamber 50 was an inert gas atmosphere heated to about 400 ° C. by a heating means. By setting the atmosphere in the processing chamber 50 under such conditions, it is possible to suppress the occurrence of roughness on the surface of the silicon semiconductor substrate 40.

[Step-720] Then, while maintaining the atmosphere at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer (the silicon semiconductor substrate 40 in the seventh embodiment) (specifically in the seventh embodiment, The ambient temperature was set to 400 ° C.), and a silicon oxide film 42 was formed on the surface of the silicon layer by an oxidation method using a wet gas. In the seventh embodiment, specifically, the steam generated in the combustion chamber (not shown) is supplied to the pipe (not shown) and the gas introduction section 5.
4 and introduced into the processing chamber 50 through the pyrogenetic oxidation method.
A 2 nm silicon oxide film was formed.

[Step-730] After that, while the introduction of the wet gas into the processing chamber 50 was continued, the atmospheric temperature in the processing chamber 50 was raised to 800 ° C. by the heating means.
In the seventh embodiment, since the heating means is disposed substantially parallel to the surface of the silicon layer, it is possible to suppress, for example, occurrence of in-plane temperature variation of the silicon semiconductor substrate when the temperature of the silicon semiconductor substrate is increased. As a result, it is possible to effectively suppress the in-plane thickness variation of the silicon oxide film formed during the temperature rise.

[Step-740] The processing chamber 50 is set at 800 ° C.
After the temperature of the inside of the inside was reached, while maintaining the atmosphere at this temperature, a silicon oxide film was further formed by an oxidation method using a wet gas. Specifically, the steam generated in the combustion chamber is supplied to the processing chamber 5 through a pipe and a gas introduction unit 54.
Then, a silicon oxide film 42 having a total thickness of 4.0 nm was formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method.

As described above, the formation of the silicon oxide film 42 on the surface of the silicon semiconductor substrate 40 is completed.
Thereafter, the inside of the processing chamber 50 may be set to an inert gas atmosphere such as a nitrogen gas or the like, the gate valve 53 may be opened, and the silicon semiconductor substrate 40 placed on the wafer table 52 may be carried out of the processing chamber 50. When it is intended to form a silicon oxide film having the following, it is preferable to perform a heat treatment described below on the silicon oxide film.

[Step-750] Thereafter, the introduction of the wet gas into the processing chamber 50 is stopped, and while the nitrogen gas is being introduced into the processing chamber 50 from the gas introduction part 54, the atmospheric temperature of the processing chamber 50 is increased by the heating means. The temperature was raised to 850 ° C. Then
Nitrogen gas containing 0.1% by volume of hydrogen chloride gas was introduced into the processing chamber 50 from the gas introduction unit 54, and heat treatment was performed for 5 minutes.

[Step-760] Thus, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate 40 is completed. Thereafter, the inside of the processing chamber 50 was set to a nitrogen gas atmosphere, the gate valve 53 was opened, and the silicon semiconductor substrate 40 mounted on the wafer table 52 was unloaded from the processing chamber 50.

The silicon oxide film described in the first embodiment, the third embodiment to the sixth embodiment can be formed by using the horizontal silicon oxide film forming apparatus described in the seventh embodiment.

Example 8 Example 8 relates to a second preferred embodiment of the method for forming a silicon oxide film according to the first aspect of the present invention, and further relates to a silicon oxide film according to the second aspect of the present invention. The present invention relates to a method for forming an oxide film. In the eighth embodiment, a silicon oxide film including a first processing chamber and a second processing chamber for forming a silicon oxide film, and a transport path connecting the first processing chamber and the second processing chamber. Using a forming apparatus, a first silicon oxide film forming step is performed in a first processing chamber, and then, a silicon layer is loaded from the first processing chamber into a second processing chamber via a transfer path, A second silicon oxide film forming step is performed in a second processing chamber. In the eighth embodiment, the silicon layer is transferred from the first processing chamber to the second processing chamber via the transfer path without being exposed to the atmosphere. That is, the atmosphere of the transfer path when the silicon layer is transferred from the first processing chamber to the second processing chamber is an inert gas atmosphere. Here, the atmospheric temperature of the transfer path when the silicon layer is transferred from the first processing chamber to the second processing chamber is made substantially equal to the atmospheric temperature in the first processing chamber in the first silicon oxide film forming step. . In the eighth embodiment, the first silicon oxide film forming step and the second silicon oxide film forming step are performed by a batch method.

In the eighth embodiment, a vertical type silicon oxide film forming apparatus whose conceptual diagram is shown in FIG. 34 and whose schematic diagrams are shown in FIGS. 35 and 36 is used. In the eighth embodiment, the silicon layer is the silicon semiconductor substrate itself.
The formed silicon oxide film functions as a gate oxide film. In the eighth embodiment, a pyrogenic oxidation method is employed as an oxidation method using a wet gas in the first silicon oxide film forming step and the second silicon oxide film forming step. After forming the silicon oxide film in the second silicon oxide film forming step, the formed silicon oxide film is
Heat treatment (furnace annealing) is performed in an inert gas atmosphere containing a halogen element (specifically, a nitrogen gas atmosphere containing a hydrogen chloride gas). Note that the heat treatment is performed in a batch manner in the second processing chamber. 33 to 36, and FIGS. 38 to 46 which are conceptual diagrams of a silicon oxide film forming apparatus and the like.
The method for forming the silicon oxide film of Example 8 will be described with reference to FIG. FIG. 37 shows the ambient temperature profile in the eighth embodiment.

The apparatus for forming a silicon oxide film shown in FIGS. 34 to 36 includes a first processing chamber 110, a second processing chamber 210, and a transfer path 120. FIG. 35 is a schematic cross-sectional view of a portion including the first processing chamber 110 along the arrow AA in FIG. 34, and FIG. 36 is an arrow B in FIG.
FIG. 4 is a schematic cross-sectional view of a portion including a second processing chamber 210 along the line −B. This vertical type silicon oxide film forming apparatus includes processing chambers 110 and 210 having a double tube structure made of quartz, and gas introduction units 112 and 212 for introducing water vapor and / or gas into the processing chambers 110 and 210. , Processing chambers 110 and 2
Gas exhaust unit 1 for exhausting water vapor and / or gas from 10
13,213 and a cylindrical heat equalizing tube 11 made of SiC.
Heaters 114 and 214 for maintaining the inside of the processing chambers 110 and 210 at a predetermined atmospheric temperature via the heaters 6 and 216. The heaters 114 and 214 are controlled by a temperature control device (not shown). Further, a transfer path 120 disposed below the first processing chamber 110 and the second processing chamber 210, a gas introduction unit 121 for introducing an inert gas such as nitrogen gas into the transfer path 120, A gas exhaust unit 122 for exhausting gas from the passage 120;
Shutters 115 and 215 that partition the transfer path 120 from the first and second processing chambers 210 and an elevator mechanism 123 for carrying the silicon semiconductor substrate into and out of the first processing chamber 110 and the second processing chamber 210. ing. A quartz boat 124 for mounting a plurality of silicon semiconductor substrates is attached to the elevator mechanism 123.
Note that the elevator mechanism 123 is movable in the left-right direction in FIG. The transport path 120 is provided with a door 125 for loading and unloading the silicon semiconductor substrate. Further, the hydrogen gas supplied to the combustion chamber 130 is combined with the oxygen gas and the combustion chamber 13.
Water vapor is generated by mixing and burning at a high temperature within zero. The water vapor is introduced into the first processing chamber 110 and the second processing chamber 210 via the pipe 131, the gas channels 111 and 211, and the gas introduction units 112 and 212. The gas flow paths 111 and 211 correspond to a space between the inner wall and the outer wall of the first processing chamber 110 and the second processing chamber 210 having the double pipe structure. Note that the combustion chamber 130 and the pipe 131 are connected to the first processing chamber 110 and the second processing chamber 21.
0 or one combustion chamber 130
Steam may be introduced into the first processing chamber 110 or the second processing chamber 210 by a pipe 131 branched from the first processing chamber 110.

[Step-800] First, the element isolation region 41 is formed on the silicon semiconductor substrate 40 in the same manner as in the first embodiment.
After forming the like, fine particles and metal impurities on the surface of the silicon semiconductor substrate 40 are removed by RCA cleaning,
The surface of the silicon semiconductor substrate 40 is washed with a 0.1% hydrofluoric acid aqueous solution and pure water to expose the surface of the silicon semiconductor substrate (see FIG. 33A).

[Step-810] Next, the plurality of silicon semiconductor substrates 40 are loaded from the door 125 into the transfer path 120 of the silicon oxide film forming apparatus shown in FIG.
24. Note that an inert gas such as nitrogen gas is introduced from the gas introduction unit 112 into the first processing chamber 110, the inside of the first processing chamber 110 is set to an inert gas atmosphere (a reduced pressure atmosphere may be used), and Heater 11 through soaking tube 116
4, the atmosphere temperature in the first processing chamber 110 is set to 400
Hold at ゜ C. In this state, the shutter 115 is closed. On the other hand, an inert gas such as a nitrogen gas is introduced into the second processing chamber 210 from the gas introduction unit 212 to make the inside of the second processing chamber 210 an inert gas atmosphere (a reduced pressure atmosphere may be used), and The ambient temperature in the second processing chamber 210 is maintained at 800 ° C. by the heater 214 via the soaking tube 216. In this state, the shutter 215 is closed.

[Step-820] After the loading of the silicon semiconductor substrate 40 into the transfer path 120 is completed, the door 12
5 is closed, an inert gas such as a nitrogen gas is introduced into the transfer path 120 from the gas introduction unit 121 and discharged from the gas exhaust unit 122, and the inside of the transfer path 120 is set to an inert gas atmosphere at room temperature (see FIG. 38). . The oxygen gas concentration in the transfer path 120 is monitored, and if the oxygen gas concentration becomes, for example, 100 ppm or less, it is determined that the inside of the transfer path 120 is sufficiently in an inert gas atmosphere. Thereafter, the shutter 115 is opened, the elevator mechanism 123 is operated, and the quartz boat 12 is opened.
Then, the silicon semiconductor substrate 40 is carried into the first processing chamber 110 having a double tube structure made of quartz (see FIG. 39). When the elevator mechanism 123 reaches the highest position, the first processing chamber 11 is moved by the base of the quartz boat 124.
0 and the conveyance path 120 are not communicated. Since the temperature of the inert gas atmosphere in the first processing chamber 110 is maintained at 400 ° C. by the heater 114, it is possible to prevent the surface of the silicon semiconductor substrate 40 from being roughened. After the loading of the silicon semiconductor substrate 40 into the first processing chamber 110, the transfer path 12 in an inert gas atmosphere is
It is preferable that the inside of 0 is heated to about 400 ° C. by a heater (not shown).

[Step-830] Next, the first processing chamber 110 is set to a temperature at which silicon atoms are not desorbed from the surface of the silicon layer (the silicon semiconductor substrate 40 in the eighth embodiment).
(In the eighth embodiment, specifically, the ambient temperature is set to 400 ° C.), the silicon oxide film 42 is formed on the surface of the silicon layer by an oxidation method using a wet gas ( (See FIG. 33B and FIG. 40).
In the eighth embodiment, specifically, hydrogen gas and oxygen gas are supplied into the combustion chamber 130 maintained at 750 ° C. to burn the hydrogen gas, and the steam generated in the combustion chamber 130 is supplied to the pipe 131. The silicon oxide film 42 is introduced into the first processing chamber 110 through the gas flow path 111 and the gas introduction unit 112, and a silicon oxide film 42 having a thickness of 1.2 nm is formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method. The wet gas may contain, for example, a hydrogen chloride gas having a concentration of 1.0% by volume.

[Step-840] Then, the silicon layer (specifically, the silicon semiconductor substrate 40) is transferred to the first processing chamber 1
From 10, it is carried into the second processing chamber 210 via the transfer path 120. Specifically, the introduction of the wet gas into the first processing chamber 110 is stopped, and an inert gas such as a nitrogen gas is introduced into the first processing chamber 110 from the gas introduction unit 112. Then, after replacing the inside of the first processing chamber 110 with an inert gas such as nitrogen gas, the elevator mechanism 123 is operated to carry the silicon semiconductor substrate 40 into the transfer path 120 (FIG. 4).
1). The inside of the transfer path 120 is an inert gas atmosphere,
Moreover, the temperature is maintained at about 400 ° C. That is, the silicon layer (specifically, the silicon semiconductor substrate 40) is transferred from the first processing chamber 110 to the second processing chamber 2 via the transfer path 120.
The temperature in the transfer path 120 at the time of loading into the substrate 10 is substantially equal to the ambient temperature of the first processing chamber 110 when the silicon oxide film 42 is formed on the silicon semiconductor substrate 40. When the elevator mechanism 123 is located at the lowermost position, the shutter 115 is closed and the elevator mechanism 123 is moved below the second processing chamber 210 (see FIG. 42).

[Step-850] Then, the shutter 21
5, the elevator mechanism 123 is operated to raise the quartz boat 124, and the silicon semiconductor substrate 40 is carried into the second processing chamber 210 having a double tube structure made of quartz (FIG. 43).
reference). When the elevator mechanism 123 reaches the highest position, the second processing chamber 21 is moved by the base of the quartz boat 124.
0 and the conveyance path 120 are not communicated. Although the temperature of the inert gas atmosphere in the second processing chamber 210 is maintained at 800 ° C. by the heater 214, a silicon oxide film 42 which also functions as a protective film is already formed on the surface of the silicon semiconductor substrate 40. Therefore, the surface of the silicon layer (silicon semiconductor substrate 40) is not roughened. The silicon semiconductor substrate 4 is transferred to the second processing chamber 210.
After loading 0, it is preferable to set the temperature in the transfer path 120 in an inert gas atmosphere to room temperature.

[Step-860] Then, the second processing chamber 2
With the inside of the chamber 10 kept at 800 ° C., a silicon oxide film is further formed by an oxidation method using a wet gas.
Specifically, hydrogen gas and oxygen gas are supplied to the combustion chamber 130 maintained at 750 ° C. to burn the hydrogen gas, and the steam generated in the combustion chamber 130 is supplied to the pipe 131, the gas passage 211, The second processing chamber 21 via the introduction unit 212
Then, a silicon oxide film 42 having a total thickness of 4.0 nm is formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method (see FIGS. 33C and 44). The wet gas may contain, for example, a hydrogen chloride gas having a concentration of 1.0% by volume.

As described above, the formation of the silicon oxide film 42 on the surface of the silicon semiconductor substrate 40 is completed.
Thereafter, the interior of the second processing chamber 210 is set to an inert gas atmosphere such as nitrogen gas, the elevator mechanism 123 is operated to lower the quartz boat 124, and then the door 125 is opened, and the silicon semiconductor substrate 40 is removed from the transfer path 120. Although it may be carried out, when it is intended to form a silicon oxide film having higher characteristics, it is preferable to perform a heat treatment described below on the silicon oxide film.

[Step-870] That is, [Step-860]
Subsequently, the introduction of the wet gas into the second processing chamber 210 is stopped, and an inert gas such as a nitrogen gas is introduced into the second processing chamber 210 from the gas introduction unit 212 while the second processing chamber 210 is being introduced.
Is raised to 850 ° C. by the heater 214 (see FIG. 45). Thereafter, for example, a nitrogen gas containing 0.1% by volume of hydrogen chloride gas is introduced into the second processing chamber 210 from the gas introduction part 212, and heat treatment is performed for 30 minutes (see FIG. 33D and FIG. 46). ). From the above,
The heat treatment of the silicon oxide film 42 is completed. Thereafter, the inside of the second processing chamber 210 is set to an inert gas atmosphere such as a nitrogen gas,
The elevator boat 123 is operated to lower the quartz boat 124, then the door 125 is opened, and the silicon semiconductor substrate 40 is unloaded from the transport path 120.

Ninth Embodiment A ninth embodiment is a modification of the eighth embodiment. In the ninth embodiment, a batch type vertical silicon oxide film forming apparatus whose schematic diagrams are shown in FIGS. 35 and 36 and whose conceptual diagram is shown in FIG. 47 is used. The vertical type silicon oxide film forming apparatus used in the ninth embodiment is different from the vertical type silicon oxide film forming apparatus described in the eighth embodiment in the first point.
120A of transfer path 120 communicating with processing chamber 110
1 of the transport path 120 communicating with the second processing chamber 210
20B, a gas introduction unit for introducing an inert gas such as nitrogen gas, and a gas exhaust unit for exhausting gas (each of which is provided in each of the transport paths 120A and 120B). 47 (not shown in FIG. 47). As described above, by dividing the transfer path 120 into two parts 120A and 120B by the shutter 126, the formation of the silicon oxide film in the first processing chamber 110 and the formation of the silicon oxide film in the second processing chamber 210 are performed. The film formation can be performed independently, for example, simultaneously, and the throughput in forming the silicon oxide film can be improved. The combustion chamber 130 and the pipe 13
1 is desirably provided independently in each of the first processing chamber 110 and the second processing chamber 210. The method of forming the silicon oxide film of the ninth embodiment will be described below with reference to FIGS. 48 to 57 which are conceptual diagrams of a silicon oxide film forming apparatus and the like. Specifically, it is the same as the method of forming the silicon oxide film of the eighth embodiment. The ambient temperature profile in the ninth embodiment is the same as that in FIG.

[Step-900] First, the element isolation region 41 is formed on the silicon semiconductor substrate 40 in the same manner as in the first embodiment.
After forming the like, fine particles and metal impurities on the surface of the silicon semiconductor substrate 40 are removed by RCA cleaning,
The surface of the silicon semiconductor substrate 40 is cleaned with a 0.1% aqueous solution of hydrofluoric acid and pure water to expose the surface of the silicon semiconductor substrate.

[Step-910] Next, the plurality of silicon semiconductor substrates 40 are loaded from the door 125A into the transfer path 120A of the silicon oxide film forming apparatus shown in FIG. Note that an inert gas such as a nitrogen gas is introduced into the first processing chamber 110 from the gas introduction unit 112,
The inside of the processing chamber 110 is made an inert gas atmosphere (may be a reduced pressure atmosphere), and a soaking tube 116 (see FIG. 35).
The atmosphere temperature in the first processing chamber 110 is maintained at 400 ° C. by the heater 114 via the heater. In this state, the shutter 115 is closed. On the other hand, an inert gas such as nitrogen gas is introduced from the gas introduction unit 212 into the second processing chamber 210, the inside of the second processing chamber 210 is set to an inert gas atmosphere (may be a reduced pressure atmosphere), and The atmosphere temperature in the second processing chamber 210 is maintained at 800 ° C. by the heater 214 via the soaking tube 216 (see FIG. 36). In this state, the shutter 215 is closed. Also, the shutter 126 provided between the transport path 120A and the transport path 120B is closed.

[Step-920] Then, the transport path 120A
After the loading of the silicon semiconductor substrate 40 into the
25A is closed, an inert gas such as a nitrogen gas is introduced into each of the transfer paths 120A and 120B from a gas inlet, and discharged from a gas exhaust section, and the inside of the transfer paths 120A and 120B is set to an inert gas atmosphere at room temperature ( See FIG. 48). The oxygen gas concentration in the transport path 120A is monitored, and if the oxygen gas concentration becomes, for example, 100 ppm or less, the transport path 12A
It is determined that the inside of 0A has sufficiently become an inert gas atmosphere.
Thereafter, the shutter 115 is opened, and the elevator mechanism 12 is opened.
3 is operated to raise the quartz boat 124, and the silicon semiconductor substrate 40 is moved to the first processing chamber 1 having a double tube structure made of quartz.
10 (see FIG. 49). The temperature of the inert gas atmosphere in the first processing chamber 110 is set to 40 by the heater 114.
Since the temperature is maintained at 0 ° C., the silicon semiconductor substrate 40
It is possible to suppress the occurrence of roughness on the surface.
After the transfer of the silicon semiconductor substrate 40 into the first processing chamber 110, the transfer paths 120A, 12A in an inert gas atmosphere are transferred.
It is preferable to heat the inside of 0B to about 400 ° C. by a heater (not shown).

[Step-930] Next, in the same manner as in [Step-830] of the eighth embodiment, the temperature is raised to a temperature at which silicon atoms are not desorbed from the surface of the silicon layer (the silicon semiconductor substrate 40 in the ninth embodiment). In a state where the atmosphere of the first processing chamber 110 is maintained (specifically, also in the ninth embodiment,
An atmosphere temperature is set to 400 ° C.), and a silicon oxide film 42 having a thickness of 1.2 nm is formed on the surface of the silicon layer by an oxidation method (pyrogenic oxidation method) using a wet gas (see FIG. 50). In the wet gas, for example, a concentration of 1.0
A volume% of hydrogen chloride gas may be contained.

[Step-940] After that, the silicon layer (specifically, the silicon semiconductor substrate 40) is transferred to the first processing chamber 1
The wafer 10 is carried into the second processing chamber 210 via the transfer paths 120A and 120B. Specifically, the first processing chamber 110
The introduction of the wet gas into the inside is stopped, and an inert gas such as a nitrogen gas is introduced into the first processing chamber 110 from the gas introduction unit 112. Then, after replacing the inside of the first processing chamber 110 with an inert gas such as nitrogen gas, the elevator mechanism 123 is operated to carry the silicon semiconductor substrate 40 into the transfer path 120A. The inside of the transport paths 120A and 120B is an inert gas atmosphere, and is maintained at about 400 ° C.
That is, the silicon layer (specifically, the silicon semiconductor substrate 4
0) from the first processing chamber 110 to the transport paths 120A, 120
Transfer path 1 when loading into the second processing chamber 210 via B
The temperature inside 20A and 120B is determined by the silicon semiconductor substrate 40.
Processing chamber 1 when silicon oxide film 42 is formed
10 is substantially equal to the ambient temperature. When the elevator mechanism 123 is located at the lowermost position, the shutter 115 is closed, the shutter 126 is opened (see FIG. 51), the elevator mechanism 123 is moved below the second processing chamber 210, and then the shutter 126 is closed. . Then, in order to form a silicon oxide film on the silicon semiconductor substrate of the next lot, the door 125A is opened, and the silicon semiconductor substrate 40 is carried into the transfer path 120A (see FIG. 52).

[Step-950] Next, the shutter 21
5, the elevator mechanism 123 is operated to raise the quartz boat 124, and the silicon semiconductor substrate 40 is carried into the second processing chamber 210 having a double-tube structure made of quartz (FIG. 53).
reference). Although the temperature of the inert gas atmosphere in the second processing chamber 210 is maintained at 800 ° C. by the heater 214, a silicon oxide film 42 which also functions as a protective film is already formed on the surface of the silicon semiconductor substrate 40. Therefore, the surface of the silicon layer (silicon semiconductor substrate 40) is not roughened. After the silicon semiconductor substrate 40 is loaded into the second processing chamber 210, it is preferable that the temperature in the transport path 120B in an inert gas atmosphere be room temperature. In the transfer path 120A and the first processing chamber 110, as in [Step-920], the door 125A is closed, and an inert gas such as nitrogen gas is introduced into the transfer path 120A from the gas introduction unit 121. After being discharged from the exhaust unit 122, the inside of the transport path 120A is set to an inert gas atmosphere at room temperature (see the state of the transport path 120A on the left side in FIG. 48).

[Step-960] Then, similarly to [Step-860] of the eighth embodiment, the inside of the second processing
While maintaining the temperature at ゜ C, a silicon oxide film is further formed by an oxidation method (pyrogenic oxidation method) using a wet gas (see FIG. 54). Here, for example, hydrogen chloride gas having a concentration of 1.0% by volume may be contained in the wet gas. In the transfer path 120A and the first processing chamber 110, the shutter 115 is opened and the elevator mechanism 123 is operated to operate the quartz boat 1 in the same manner as in [Step-920].
Then, the silicon semiconductor substrate 40 is carried into the first processing chamber 110 having a double tube structure made of quartz (see the state of the transfer path 120A on the left side in FIG. 49).

As described above, the formation of the silicon oxide film 42 on the surface of the silicon semiconductor substrate 40 in the second processing chamber 210 is completed.
The interior of 10 may be set to an atmosphere of an inert gas such as nitrogen gas, the elevator mechanism 123 may be operated to lower the quartz boat 124, the door 125B may be opened, and the silicon semiconductor substrate 40 may be unloaded from the transfer path 120B. If you intend to form a silicon oxide film with high characteristics,
The heat treatment described below is preferably performed on the silicon oxide film. Note that the process after [Step-930] is performed on the silicon semiconductor substrate carried into the first processing chamber 110.

[Step-970] That is, similarly to [Step-870] of the eighth embodiment, after [Step-960], introduction of the wet gas into the second processing chamber 210 is stopped, and nitrogen gas or the like is removed. Inert gas from the gas introduction unit 212 to the second processing chamber 21
0, the ambient temperature of the second processing chamber 210 is raised to 850 ° C. by the heater 214 (FIG. 5).
5). Then, for example, 0.1% by volume of hydrogen chloride gas
The contained nitrogen gas is introduced from the gas introduction part 212 into the second processing chamber 210, and heat treatment is performed for 30 minutes (see FIG. 56). Thus, the heat treatment of the silicon oxide film 42 is completed. Thereafter, the interior of the second processing chamber 210 is set to an inert gas atmosphere such as a nitrogen gas or the like, the elevator mechanism 123 is operated to lower the quartz boat 124, then the door 125B is opened, and the silicon semiconductor substrate 40 is removed from the transfer path 120B. Take it out. Next, the door 125B is closed, and an inert gas such as nitrogen gas is introduced into the transfer path 120B.
The ambient temperature is set to about 400 ° C. (see FIG. 57).

In the ninth embodiment described above, the timing of forming the silicon oxide film on the silicon semiconductor substrate of the next lot is an example and can be changed as appropriate.

(Embodiment 10) Embodiment 10 is a modification of embodiment 8. Example 10 is different from Example 8 in that
The silicon oxide film forming step and the second silicon oxide film forming step are performed in a horizontal single-wafer processing chamber. That is, in the first and second processing chambers, a silicon oxide film is formed on one silicon semiconductor substrate in a single-wafer manner. In the tenth embodiment, the heat treatment is performed in a batch mode using a furnace annealing apparatus, but may be performed in a single wafer mode.

In the tenth embodiment, an oxide film forming apparatus whose conceptual plan view is shown in FIG. 58 is used. The oxide film forming apparatus includes a loader / unloader 300 and a transfer path 30.
1, the first processing device 302 and the second processing device 303
And a furnace annealing device 304. Furnace annealing apparatus 304 has substantially the same structure as vertical silicon oxide film forming apparatus shown in FIG. 13 except that there is no combustion chamber, as shown in FIG. 59. The furnace annealing device 3
In FIG. 04, the same components as those of the silicon oxide film forming apparatus shown in FIG.
The structures of the first processing apparatus 302 and the second processing apparatus 303 can be the same as those of the silicon oxide film forming apparatus shown in FIG. 31 or FIG.

In Examples 8 and 9, a vertical type silicon oxide film forming apparatus in which a processing chamber (oxidizing furnace) made of quartz was held vertically was used. By the way, when a vertical type silicon oxide film forming apparatus is used, the heater 11
Since 4,214 are provided, the temperature of the peripheral portion of the silicon layer (for example, a silicon semiconductor substrate) is always higher than that of the central portion during the temperature rise of the silicon layer. as a result,
When the silicon oxide film is formed during the heating of the silicon layer,
There is a possibility that the thickness of the silicon oxide film is larger at the peripheral portion of the silicon layer (for example, a silicon semiconductor substrate) than at the central portion. In the tenth embodiment, since the silicon layer is heated by the heating means disposed substantially parallel to the surface of the silicon layer, it is possible to reduce temperature variations in the plane of the silicon layer. As a result, it is possible to suppress occurrence of in-plane thickness variation of the formed silicon oxide film.

A method for forming a silicon oxide film according to the tenth embodiment will be described below with reference to FIGS.

[Step-1000] First, an element isolation region and the like are formed in a silicon semiconductor substrate in the same manner as in Example 1, and then fine particles and metal impurities on the surface of the silicon semiconductor substrate are removed by RCA cleaning. Next, the surface of the silicon semiconductor substrate is washed with a 0.1% hydrofluoric acid aqueous solution and pure water to expose the surface of the silicon semiconductor substrate 40.

[Step-1010] In the transport path 301, the first
The interior of each of the processing chambers 50 of the processing apparatus 302 and the second processing apparatus 303, and the inside of the substrate loading / unloading section 20 and the processing chamber 10 of the furnace annealing apparatus 304 are kept in an inert gas atmosphere such as a nitrogen gas. The inert gas atmosphere temperature in the processing chamber 50 of the first processing apparatus 302 was set to 400 ° C., the inert gas atmosphere temperature of the processing chamber 50 in the second processing apparatus 303 was set to 800 ° C., and the furnace annealing apparatus was used. 304 processing chamber 1
It is preferable that the inert gas atmosphere temperature in 0 is set to 850 ° C. Then, the silicon layer (specifically, the silicon semiconductor substrate 40) is carried into the transfer path 301 from the loader / unloader 300, and further, the silicon semiconductor substrate is placed on the wafer table 52. Then, FIG. 32), the gate valve 53 of the first processing apparatus 302 is opened, and the processing chamber 50 corresponding to the first processing chamber is opened.
Then, the gate valve 53 is closed. Since the atmosphere temperature in the processing chamber 50 is about 400 ° C., it is possible to suppress the occurrence of roughness on the surface of the silicon semiconductor substrate 40.

[Step-1020] Then, while maintaining the atmosphere at a temperature at which silicon atoms do not desorb from the surface of the silicon layer (the silicon semiconductor substrate 40 in the tenth embodiment) (specifically, The ambient temperature is set to 400 ° C.) and a silicon oxide film is formed on the surface of the silicon layer by an oxidation method using a wet gas (pyrogenic oxidation method). In Example 10,
Specifically, similarly to the eighth embodiment, the steam generated in the combustion chamber (not shown) is supplied to the pipe (not shown) and the gas introduction unit 5.
4 and introduced into the processing chamber 50 through the pyrogenetic oxidation method.
A 2 nm silicon oxide film is formed. The wet gas may contain, for example, a hydrogen chloride gas having a concentration of 1.0% by volume. Further, the inert gas in the transfer path 301 is heated, and the temperature of the inert gas atmosphere in the transfer path 301 is set to 400 degrees.
It is preferable to keep it around ゜ C.

[Step-1030] Thereafter, the introduction of the wet gas into the processing chamber 50 is stopped, and the inside of the processing chamber 50 is heated to 400 ° C.
The gate valve 53 is opened and the silicon semiconductor substrate 4 placed on the wafer stage 52 is set to an inert atmosphere such as nitrogen gas.
0 is the transfer path 30 from the processing chamber 50 corresponding to the first processing chamber.
1 and then open the gate valve 53 of the second processing apparatus 303 shown in FIG. 31 (or FIG. 32) to carry in the processing chamber 50 corresponding to the second processing chamber. Close. At this time, the atmosphere in the processing chamber 50 corresponding to the second processing chamber is an inert gas atmosphere heated to about 800 ° C. by the heating means. However, the silicon layer (for example, the silicon semiconductor substrate 40) is subjected to the second processing via the transfer path 301 from the first processing apparatus 302 in a state where the silicon oxide film which also functions as a protective film is already formed on the surface of the silicon layer. Device 3
03 in the transfer path 301 and the second processing chamber 3
No irregularities (roughness) occur on the surface of the silicon layer even if the inside of the substrate is in a non-oxidizing atmosphere.

[Step-1040] Next, while maintaining the ambient temperature in the processing chamber 50 corresponding to the second processing chamber at 800 ° C., an oxidation method using a wet gas was performed in the same manner as in Example 8. A silicon oxide film is formed on the surface of the silicon layer. In the tenth embodiment, specifically, similarly to the eighth embodiment, the steam generated in the combustion chamber (not shown) is supplied to the second processing chamber through a pipe (not shown) and a gas introduction unit 54. Is introduced into the processing chamber 50 corresponding to the thickness of the silicon semiconductor substrate 40 by a pyrogenic oxidation method.
A 0 nm silicon oxide film is formed. The wet gas may contain, for example, a hydrogen chloride gas having a concentration of 1.0% by volume. The temperature of the inert gas atmosphere in the transport path 301 may be room temperature.

As described above, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate is completed. Thereafter, the second processing chamber is set to an inert gas atmosphere such as nitrogen gas, the gate valve 53 is opened, and the wafer table 52 is opened. The mounted silicon semiconductor substrate 40 may be carried out of the processing chamber 50 to the transfer path 301 and carried out of the system via the loader / unloader 300. However, the formation of a silicon oxide film having higher characteristics may be performed. If intended, it is preferable to perform the heat treatment described below on the silicon oxide film.

[Step-1050] That is, the silicon layer (for example, the silicon semiconductor substrate 40) is sequentially loaded into the substrate loading / unloading section 20 of the furnace annealing apparatus 304 shown in FIG. 59 through a door (not shown). When the quartz boat 24 is filled with the plurality of silicon semiconductor substrates, a door (not shown) is closed, the elevator mechanism 23 is operated to raise the quartz boat 24, and the silicon semiconductor substrate 40 is carried into the processing chamber 10. Then, for example, a nitrogen gas containing 0.1% by volume of hydrogen chloride gas is introduced into the processing chamber 310 from the gas introduction unit 12, and heat treatment is performed at an atmosphere temperature of 850 ° C. for 30 minutes. Thus, the heat treatment of the silicon oxide film is completed.
Thereafter, the interior of the processing chamber 10 is set to an inert gas atmosphere such as a nitrogen gas, and the elevator mechanism 23 is operated to lower the quartz boat 24.
To the outside of the system via the loader / unloader 300.

Incidentally, instead of using the furnace annealing apparatus shown in FIG. 59, in the processing chamber 50 corresponding to the second processing chamber,
Alternatively, the silicon semiconductor substrate may be carried into an annealing apparatus having a structure substantially similar to that shown in FIGS. 31 and 32, and heat treatment may be performed subsequent to formation of the silicon oxide film. For example, when performing the heat treatment in the processing chamber 50 corresponding to the second processing chamber, in [Step-1040], the introduction of the wet gas is stopped, and an inert gas (for example, nitrogen gas) is used.
Is introduced from the gas introduction unit 54 into the processing chamber 50, and the temperature of the atmosphere in the processing chamber 50 is raised to 850 ° C. by the heating means. Thereafter, for example, an inert gas (for example, nitrogen gas) containing 0.1% by volume of hydrogen chloride gas is introduced into the processing chamber 50 from the gas introduction unit 54, and heat treatment is performed for 5 minutes.

In the silicon oxide film forming apparatus shown in FIG. 58, a shutter is provided between a portion of the transport path communicating with the first processing device 302 and a portion of the transport route communicating with the second processing device 303. May be provided. Further, the first temperature is set to a temperature at which silicon atoms do not desorb from the surface of the silicon layer.
The first silicon oxide film forming step of forming a silicon oxide film on the surface of the silicon layer by an oxidation method using a wet gas while maintaining the atmosphere in the processing chamber of FIG. The second silicon oxide film forming step performed in the chamber 50 and further forming a silicon oxide film by an oxidation method using a wet gas uses a batch type vertical silicon oxide film forming apparatus shown in FIG. You can also do it.

Example 11 Example 11 relates to a method for forming a silicon oxide film in the third preferred embodiment of the present invention. That is, the temperature of the atmosphere when the formation of the silicon oxide film having the desired thickness is completed is within the temperature range in which silicon atoms are not desorbed from the surface of the silicon layer, or is set to 500 ° C. or less. In the eleventh embodiment, a silicon oxide film is formed by a batch method. Specifically, in Example 11, the vertical type silicon oxide film forming apparatus shown in FIG. 13 was used. Example 11
In, the silicon layer was composed of a silicon semiconductor substrate. The formed silicon oxide film functions as a gate oxide film. In Example 11, a pyrogenic oxidation method was employed as an oxidation method using a wet gas in the step of forming a silicon oxide film. After a silicon oxide film is further formed to a desired thickness, the formed silicon oxide film is heat-treated in an inert gas atmosphere containing a halogen element (a nitrogen gas atmosphere containing a hydrogen chloride gas). (Furnace annealing treatment). Hereinafter, FIGS. 61 to 63
The method for forming the silicon oxide film of Example 11 will be described with reference to FIG. FIG. 60A schematically shows the ambient temperature profile in the eleventh embodiment.

[Step-1100] First, after forming an element isolation region and the like in the silicon semiconductor substrate in the same manner as in the first embodiment, fine particles and metal impurities on the surface of the silicon semiconductor substrate are removed by RCA cleaning. Next, the surface of the silicon semiconductor substrate is washed with a 0.1% hydrofluoric acid aqueous solution and pure water to expose the surface of the silicon semiconductor substrate.

[Step-1110] Next, the plurality of silicon semiconductor substrates 40 were loaded into the substrate loading / unloading section 20 of the silicon oxide film forming apparatus shown in FIG. . Note that nitrogen gas is introduced from the gas introduction unit 12 into the processing chamber 10, the inside of the processing chamber 10 is set to an inert gas atmosphere such as a nitrogen gas (the pressure may be a reduced pressure atmosphere), and the heater is connected via the soaking tube 16. The temperature of the atmosphere in the processing chamber 10 was maintained at 250 ° C. by means of 14. still,
In this state, the shutter 15 is closed (see FIG. 61A).

[Step-1120] After the loading of the silicon semiconductor substrate 40 into the substrate loading / unloading section 20 is completed,
The door (not shown) is closed, and the gas introduction unit 2 is inserted into the substrate loading / unloading unit 20.
Nitrogen gas is introduced from 1 and discharged from the gas exhaust unit 22,
The inside of the substrate loading / unloading section 20 was set to a nitrogen gas atmosphere. The oxygen gas concentration in the substrate loading / unloading section 20 is monitored, and if the oxygen gas concentration becomes, for example, 100 ppm or less, it is determined that the inside of the substrate loading / unloading section 20 has a sufficient nitrogen gas atmosphere. Thereafter, the shutter 15 is opened (see FIG. 61B), the elevator mechanism 23 is operated, and the quartz boat 24 is opened.
(A rising speed: 300 mm / min), and the silicon semiconductor substrate 40 was carried into the processing chamber 10 having a double tube structure made of quartz. When the elevator mechanism 23 reaches the highest position, the base of the quartz boat 24 stops communication between the processing chamber 10 and the substrate loading / unloading section 20. Since the temperature of the atmosphere in the processing chamber 10 is maintained at 250 ° C. by the heater 14, that is, the temperature of the processing chamber 10 is maintained at an atmospheric temperature at which silicon atoms are not desorbed from the surface of the silicon layer. Generation of roughness on the surface of the substrate 40 can be suppressed.

[Step-1130] Next, the atmosphere temperature in the processing chamber 10 was set to 300 ° C. by the heater 14 via the soaking tube 16 (see FIG. 62A). Thereafter, formation of a silicon oxide film was started on the surface of the silicon layer by an oxidation method using a wet gas at an ambient temperature at which silicon atoms were not desorbed from the surface of the silicon layer (see FIG. 62B). Alternatively, the formation of a silicon oxide film on the surface of the silicon layer was started by an oxidation method using a wet gas at an ambient temperature of 500 ° C. or higher at a temperature at which the wet gas did not condense on the surface of the silicon layer. Specifically, the silicon layer (also in the eleventh embodiment, the silicon semiconductor substrate 4
With the ambient temperature kept at a temperature at which silicon atoms do not desorb from the surface of (0) (specifically, in the eleventh embodiment, the ambient temperature was set to 300 ° C.), silicon was oxidized using a wet gas. A silicon oxide film was formed on the surface of the layer. That is, in the eleventh embodiment, the pipes 32, 3
3 to supply oxygen gas and hydrogen gas into the combustion chamber 30, and introduce steam generated in the combustion chamber 30 into the processing chamber 10 through the pipe 31, the gas passage 11, and the gas introduction unit 12. A silicon oxide film having a thickness of 1.2 nm was formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method. The thickness of the silicon oxide film is a thickness corresponding to several molecular layers of SiO ₂ , and is a thickness sufficient to function as a protective film even in consideration of steps on the surface of the silicon semiconductor substrate. The silicon oxide film may be formed using a wet gas containing 0.1% by volume of hydrogen chloride gas, for example.

[Step-1140] Thereafter, introduction of the wet gas into the processing chamber 10 is stopped, and an inert gas (nitrogen gas) is introduced.
Is introduced into the processing chamber 10 through the pipe 32, the combustion chamber 30, the pipe 31, the gas flow path 11, and the gas introduction unit 12, and the atmosphere temperature in the processing chamber 10 of the silicon oxide film forming apparatus is reduced. The temperature was raised to 450 ° C. by the heater 14 via the heater 16 (see FIG. 63A). The heating rate was 10 ° C./min. Even when the temperature is raised to 450 ° C., the surface of the silicon layer (silicon semiconductor substrate 40) is not roughened because the temperature is within an atmospheric temperature range in which silicon atoms are not desorbed from the surface of the silicon layer.

[Step-1150] After the temperature of the atmosphere in the processing chamber 10 was stabilized at 450 ° C., a silicon oxide film was further formed by an oxidation method using a wet gas while maintaining the atmosphere at this temperature. . Specifically, again, the pipe 3
Oxygen gas and hydrogen gas are supplied into the combustion chamber 30 through the pipes 2 and 33, and the steam generated in the combustion chamber 30 is supplied to the pipe 31,
A silicon oxide film having a total thickness of 3.7 nm was formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method by introducing the silicon oxide film into the processing chamber 10 through the gas flow path 11 and the gas introduction unit 12 ((B in FIG. 63). )reference). The ambient temperature (450 ° C. in Example 11) when the formation of the silicon oxide film having a desired thickness is completed is 500 ° C. or less. The silicon oxide film may be formed using a wet gas containing 0.1% by volume of hydrogen chloride gas, for example.

As described above, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate 40 is completed. Thereafter, the interior of the processing chamber 10 is set to an inert gas atmosphere such as nitrogen gas and the elevator mechanism 23 is operated to operate the quartz boat 24. (Descent speed: 200 mm / min), and then the door (not shown) may be opened and the silicon semiconductor substrate 40 may be carried out. However, if a silicon oxide film having higher characteristics is intended, Is preferably applied to the silicon oxide film.

[Step-1160] That is, after that, the silicon layer (for example, the silicon semiconductor substrate 40) is sequentially formed as shown in FIG.
Are carried into the substrate carrying-in / out section 20 of the furnace annealing apparatus shown in FIG. When the quartz boat 24 is filled with a plurality of silicon semiconductor substrates, the door (not shown) is closed, the elevator mechanism 23 is operated to raise the quartz boat 24 (elevation speed: 200 mm / min), and the silicon semiconductor substrate 40 is processed. It is carried into the room 10. The atmosphere in the processing chamber 10 is set to a nitrogen gas atmosphere at 850 ° C. After the silicon semiconductor substrate 40 is carried into the processing chamber 10, for example, a nitrogen gas containing 0.1% by volume of hydrogen chloride gas is introduced into the processing chamber 10 from the gas introduction unit 12, and at an atmosphere temperature of 850 ° C. Heat treatment is performed for 30 minutes. Thus, the heat treatment of the silicon oxide film is completed. Thereafter, the interior of the processing chamber 10 is set to an inert gas atmosphere such as a nitrogen gas or the like, the elevator mechanism 23 is operated to lower the quartz boat 24, and then a door (not shown) is opened to carry out the furnace from the furnace annealing apparatus.

[Step-1170] Through the above, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate 40 is completed. In the eleventh embodiment, using the silicon semiconductor substrate on which the silicon oxide film has been formed in the same manner as in the first embodiment, a polysilicon is formed on the silicon oxide film based on a known CVD technique, photolithography technique, and dry etching technique. A gate electrode having a polycide structure composed of silicon and tungsten silicide was formed, and a MOS capacitor was manufactured.

The value of Q _BD at 50% of the cumulative defect rate of the MOS capacitor manufactured in Example 11 was compared with the value of Q _BD at 50% of the cumulative defective rate of the MOS capacitor in Comparative Example 1. As a result, the value of Q _BD in Example 11 was 51 C / cm ² , whereas that in Comparative Example 1 was 12 C / cm ² . That is, the value of Q _BD in Example 11 was about four times higher than the value of Q _BD in Comparative Example 1.

(Embodiment 12) Embodiment 12 is a modification of embodiment 11. Example 12 is different from Example 11 in that
The point is that the ambient temperature profile is different. FIG. 6 schematically shows the ambient temperature profile in Example 12.
0 (B). Hereinafter, a method for forming the silicon oxide film of Example 12 will be described.

[Step-1200] First, an element isolation region and the like are formed in a silicon semiconductor substrate in the same manner as in Example 1, and then fine particles and metal impurities on the surface of the silicon semiconductor substrate are removed by RCA cleaning. Next, the surface of the silicon semiconductor substrate is washed with a 0.1% hydrofluoric acid aqueous solution and pure water to expose the surface of the silicon semiconductor substrate.

[Step-1210] Next, a plurality of silicon semiconductor substrates 40 were loaded into the substrate loading / unloading section 20 of the silicon oxide film forming apparatus shown in FIG. . In addition, nitrogen gas was introduced into the processing chamber 10 from the gas introduction unit 12, the inside of the processing chamber 10 was set to an inert gas atmosphere such as a nitrogen gas (a reduced pressure atmosphere may be used), and kept at room temperature. In this state, the shutter 15 is closed.

[Step-1220] After the loading of the silicon semiconductor substrate 40 into the substrate loading / unloading section 20 is completed,
The door (not shown) is closed, and the gas introduction unit 2 is inserted into the substrate loading / unloading unit 20.
Nitrogen gas is introduced from 1 and discharged from the gas exhaust unit 22,
The inside of the substrate loading / unloading section 20 was set to a nitrogen gas atmosphere. The oxygen gas concentration in the substrate loading / unloading section 20 is monitored, and if the oxygen gas concentration becomes, for example, 100 ppm or less, it is determined that the inside of the substrate loading / unloading section 20 has a sufficient nitrogen gas atmosphere. After that, the shutter 15 is opened and the elevator mechanism 2 is opened.
3 to raise the quartz boat 24 (ascending speed:
(500 mm / min), the silicon semiconductor substrate 40 was carried into the processing chamber 10 having a double tube structure made of quartz. Thereafter, the temperature of the atmosphere in the processing chamber 10 was increased by the heater 14.
When the temperature of the atmosphere in the processing chamber 10 reached 150 ° C., formation of a silicon oxide film on the surface of the silicon layer was started by an oxidation method using a wet gas. That is, Example 12
Also, oxygen gas and hydrogen gas are supplied into the combustion chamber 30 through the pipes 32 and 33, and the steam generated in the combustion chamber 30 is supplied through the pipe 31, the gas flow path 11, and the gas introduction unit 12 into the processing chamber. 10 and the formation of a silicon oxide film on the surface of the silicon semiconductor substrate 40 was started by the pyrogenic oxidation method. Introduction of a wet gas into the processing chamber 10,
Further, the temperature of the atmosphere in the processing chamber 10 was continuously raised at a constant rate. When the temperature of the atmosphere in the processing chamber 10 reached 500 ° C., a silicon oxide film having a thickness of 3.5 nm was formed. At this point, the introduction of the wet gas into the processing chamber 10 was stopped. That is, the ambient temperature (500 ° C. in Example 12) when the formation of the silicon oxide film having the desired thickness was completed was set to 500 ° C. or less. The silicon oxide film may be formed using a wet gas containing 0.1% by volume of hydrogen chloride gas, for example.

[Step-1230] Since the formation of the silicon oxide film on the surface of the silicon semiconductor substrate 40 is completed by the above, the interior of the processing chamber 10 is set to an inert gas atmosphere such as a nitrogen gas, and the elevator mechanism 23 is operated. Then, the quartz boat 24 is lowered, then the door (not shown) is opened, and the silicon semiconductor substrate 40 may be carried out. However, when the formation of a silicon oxide film having higher characteristics is intended, It is preferable to perform heat treatment on the silicon oxide film by the same method as in [Step-1160].

(Thirteenth Embodiment) The thirteenth embodiment is also a modification of the eleventh embodiment. In Example 13, the silicon oxide film was formed using the silicon oxide film forming apparatus shown in FIG. 31 or FIG. After the formation of the silicon oxide film,
Heat treatment of the silicon oxide film was performed by a batch method. Hereinafter, a method for forming the silicon oxide film of Example 13 will be described. An atmosphere temperature profile in Example 13 is shown in FIG.

[Step-1300] First, after a device isolation region and the like are formed in a silicon semiconductor substrate in the same manner as in Example 1, fine particles and metal impurities on the surface of the silicon semiconductor substrate are removed by RCA cleaning. Next, the surface of the silicon semiconductor substrate was washed with a 0.1% aqueous solution of hydrofluoric acid and pure water to expose the surface of the silicon semiconductor substrate.

[Step-1310] Next, the silicon semiconductor substrate 40 placed on the wafer stage 52 is opened by opening the gate valve 53 of the silicon oxide film forming apparatus shown in FIG. Then, the gate valve 53 was closed. At this time, the atmosphere in the processing chamber 50 is
The atmosphere was an inert gas atmosphere heated to about 250 ° C. by heating means. By setting the atmosphere in the processing chamber 50 under such conditions, the silicon semiconductor substrate 40
It is possible to suppress the occurrence of roughness on the surface.

[Step-1320] Then, after the inside of the processing chamber 50 is heated to 300 ° C. by a heating means, the temperature is set to a temperature at which silicon atoms are not desorbed from the surface of the silicon layer (the silicon semiconductor substrate 40 also in the thirteenth embodiment). In a state where the atmosphere was maintained (specifically, in Example 13, the atmosphere temperature was set to 300 ° C.), a silicon oxide film was formed on the surface of the silicon layer by an oxidation method using a wet gas.
In the thirteenth embodiment, specifically, steam generated in a combustion chamber (not shown) is introduced into a processing chamber 50 through a pipe (not shown) and a gas introduction unit 54, and the pyrogenic oxidation method is performed. As a result, a silicon oxide film having a thickness of 1.2 nm was formed on the surface of the silicon semiconductor substrate 40. The silicon oxide film may be formed using a wet gas containing 0.1% by volume of hydrogen chloride gas, for example.

[Step-1330] Thereafter, while the introduction of the wet gas into the processing chamber 50 was continued, the ambient temperature in the processing chamber 50 was raised to 450 ° C. by the heating means. In the thirteenth embodiment as well, since the heating means is disposed substantially parallel to the surface of the silicon layer, it is possible to suppress the occurrence of in-plane temperature variation of the silicon semiconductor substrate when the temperature of the silicon semiconductor substrate is raised, for example. As a result, it is possible to effectively suppress the in-plane thickness variation of the silicon oxide film formed during the temperature rise.

[Step-1340] Processing chamber 5 at 450 ° C.
After the temperature of the atmosphere reached 0, while maintaining the atmosphere at this temperature, a silicon oxide film was further formed by an oxidation method using a wet gas. Specifically, water vapor generated in the combustion chamber is introduced into the processing chamber 50 through a pipe and a gas introduction unit 54, and a silicon oxide film having a total thickness of 4.0 nm is formed on the surface of the silicon semiconductor substrate 40 by a pyrogenic oxidation method. Was formed. The silicon oxide film may be formed using a wet gas containing 0.1% by volume of hydrogen chloride gas, for example.

As described above, the formation of the silicon oxide film on the surface of the silicon semiconductor substrate 40 is completed. Thereafter, the inside of the processing chamber 50 is set to an inert gas atmosphere such as nitrogen gas, the gate valve 53 is opened, and the wafer table 52 is opened. The mounted silicon semiconductor substrate 40 may be carried out of the processing chamber 50. However, when the formation of a silicon oxide film having higher characteristics is intended, a heat treatment described below may be performed on the silicon oxide film. preferable.

[Step-1350] Thereafter, similarly to [Step-1160] of the eleventh embodiment, the plurality of silicon semiconductor substrates 40 were subjected to a heat treatment using a furnace annealing apparatus.

It is to be noted that the silicon semiconductor substrate 4
0, the introduction of the wet gas into the processing chamber 50 is stopped, and nitrogen gas is supplied from the gas introduction unit 54 to the processing chamber 50.
The temperature of the atmosphere in the processing chamber 50 was raised to 850 ° C. by heating means, and then nitrogen gas containing 0.1% by volume of hydrogen chloride gas was introduced into the processing chamber 50 from the gas introduction unit 54. It may be introduced and heat-treated for 5 minutes.
Further, a silicon oxide film can be formed based on the same ambient temperature profile as in the twelfth embodiment.

Embodiment 14 In Embodiment 14, a silicon oxide film formed by the method of forming a silicon oxide film of the present invention is formed on a silicon semiconductor substrate before a gate oxide film is formed on the surface of the silicon semiconductor substrate. Oxide film. Note that the silicon layer is formed of a silicon semiconductor substrate. Specifically, an oxide film formed on the silicon semiconductor substrate before the gate oxide film is formed on the surface of the silicon semiconductor substrate is replaced with an oxide film for forming an element isolation region (that is, an element isolation region having a LOCOS structure or a trench structure). In the formation process, a base oxide film for depositing a silicon nitride film) was formed, and further, a sacrificial oxide film was formed. Hereinafter, a method for forming the silicon oxide film of Example 14 will be described.

[Step-1400] First, an RCA cleaning is performed on a silicon semiconductor substrate, which is an N-type silicon wafer doped with phosphorus and having a diameter of 8 inches (prepared by the CZ method) to remove fine particles and fine particles on the surface of the silicon semiconductor substrate. After removing metal impurities, the surface of the silicon semiconductor substrate is washed with a 0.1% aqueous solution of hydrofluoric acid and pure water to expose the surface of the silicon semiconductor substrate. Most of the surface of the silicon semiconductor substrate is terminated with hydrogen, and a very small portion is terminated with fluorine.

[Step-1410] Next, an element isolation region having a LOCOS structure is formed in a silicon semiconductor substrate based on a known method. At this time, a base oxide for depositing a silicon nitride film is formed. The film is formed by the method for forming a silicon oxide film of the present invention. That is, [Step-110] to [Step-150] of the first embodiment are executed, and finally a 8.0 nm silicon oxide film is formed on the surface of the silicon semiconductor substrate. When the element isolation region has a trench structure, a silicon oxide film (base oxide film) of 10 nm may be finally formed on the surface of the silicon semiconductor substrate.

[Step-1420] Thereafter, based on a known method, an element isolation region having a LOCOS structure or a trench structure is formed using the formed silicon oxide film as a base oxide film. That is, a silicon nitride film is formed on the base oxide film by the CVD method, and the silicon nitride film is patterned to expose a portion of the silicon semiconductor substrate where an element isolation region is to be formed. Thereafter, in order to form an element isolation region having a LOCOS structure, the surface of the silicon semiconductor substrate is oxidized based on a conventional thermal oxidation method, thereby forming an element isolation region. In order to form an element isolation region having a trench structure, a silicon semiconductor substrate is etched using a patterned silicon nitride film as a mask to form a trench, and then an insulating layer made of, for example, SiO ₂ is formed on the entire surface by a CVD method. Is deposited. After that, the insulating layer and the silicon nitride film on the silicon semiconductor substrate are etched back or chemically and mechanically polished (CMP).
Remove with. As a result, an element isolation region in which the trench provided in the silicon semiconductor substrate is filled with SiO ₂ can be formed.

[Step-1430] After forming the element isolation region, the surface of the silicon semiconductor substrate is oxidized again to remove defects such as white ribbons introduced into the silicon semiconductor substrate. The oxide film obtained by this is called a sacrificial oxide film. In Example 14, this sacrificial oxide film is also formed based on the method for forming a silicon oxide film of the present invention. That is, [Step-110] to [Step-1] of Example 1
50] (however, since it is necessary to form a thick silicon oxide film, the ambient temperature in [Step-150] is preferably set to about 900 ° C.), and finally the surface of the silicon semiconductor substrate is heated to about 900 ° C. A 10 nm silicon oxide film is formed.

[Step-1440] Next, well ion implantation, channel stop ion implantation, and threshold adjustment ion implantation are performed on the silicon semiconductor substrate, and then a silicon oxide film (sacrificial oxide film) on the surface of the silicon semiconductor substrate is formed. To 0.
Etching is performed using a 1% aqueous solution of hydrofluoric acid to remove it. Thereafter, RCA cleaning is performed on the silicon semiconductor substrate to remove fine particles and metal impurities on the surface of the silicon semiconductor substrate, and then, the surface of the silicon semiconductor substrate is cleaned with a 0.1% aqueous hydrofluoric acid solution and pure water. Then, the surface of the silicon semiconductor substrate is exposed. Thereafter, [Step-110] to [Step-150] of Example 1, and further, [Step-160] to [Step-170] as necessary,
A silicon oxide film functioning as a gate oxide film is formed on a surface of a silicon semiconductor substrate.

In the fourteenth embodiment, the underlying oxide film or the sacrificial oxide film is formed based on the silicon oxide film forming method of the present invention, so that the interface between the underlying oxide film or the sacrificial oxide film and the silicon semiconductor substrate has irregularities. As a result, the surface of the silicon semiconductor substrate before forming the gate oxide film can be kept flat, and the electrical reliability of the gate oxide film formed in [Step-1440] can be maintained. Can be prevented from lowering.

In the fourteenth embodiment, the method of forming the silicon oxide film described in the first embodiment is applied exclusively. However, the method of forming the base oxide film and the sacrificial oxide film is described in the first embodiment. The method for forming the silicon oxide film is not limited to the method for forming the silicon oxide film, and the method for forming the silicon oxide film described in the other embodiments can be applied.

As described above, the present invention has been described based on the preferred embodiments, but the present invention is not limited to these embodiments. The various conditions and the structure of the silicon oxide film forming apparatus described in the embodiments are merely examples, and can be changed as appropriate. The formation of the silicon oxide film is not only a pyrogenic oxidation method, but also an oxidation method using water vapor generated by heating pure water, an oxidation method using water vapor generated by bubbling heated pure water with an oxygen gas or an inert gas, Alternatively, a method using these oxidation methods in combination can be used. An oxidation method in a first silicon oxide film forming step;
An oxidation method different from the oxidation method in the second silicon oxide film forming method may be used. Alternatively, the oxidation method in forming the silicon oxide film in the first processing chamber and the oxidation method in forming the silicon oxide film in the second processing chamber may be different oxidation methods.

For example, in [Step-140] of the first embodiment, an inert gas (for example, nitrogen gas)
The temperature of the atmosphere in the processing chamber 10 of the silicon oxide film forming apparatus was raised by the heater 14 to the temperature for performing the second silicon oxide film forming step while introducing the processing chamber 10 into the processing chamber 10, but instead. While the inert gas (for example, nitrogen gas) containing, for example, 0.1% by volume of hydrogen chloride gas is introduced into the processing chamber 10 from the gas introduction unit 12, the atmospheric temperature in the processing chamber 10 of the silicon oxide film forming apparatus is changed. May be heated to an ambient temperature for performing the second silicon oxide film forming step by the heater 14. In [Step-730] of the seventh embodiment, the processing chamber 50
Instead of raising the ambient temperature in the processing chamber 50 to the ambient temperature for performing the second silicon oxide film forming step by the heating means while continuing to introduce the wet gas into the chamber, for example, hydrogen chloride gas is reduced to zero. While introducing a wet gas containing 1% by volume into the processing chamber 50, the temperature of the atmosphere in the processing chamber 50 may be raised to the atmospheric temperature for executing the second silicon oxide film forming step by the heating means. .

In Examples 1 to 10, the temperature of the atmosphere in the processing chamber was raised to 850 ° C. by a heating means such as a heater while introducing an inert gas (for example, nitrogen gas) from the gas inlet into the processing chamber. Instead, while introducing an inert gas (for example, nitrogen gas) containing, for example, 0.1% by volume of hydrogen chloride gas from the gas introduction unit into the processing chamber, the temperature of the atmosphere in the processing chamber is increased by a heater or the like. The temperature may be raised to 850 ° C. by means.

In the embodiment, the silicon oxide film is formed exclusively on the surface of the silicon semiconductor substrate, or the silicon oxide film is formed on the epitaxial silicon layer formed on the substrate. On the surface of an epitaxial silicon layer formed by a selective epitaxial growth method formed on the surface of a silicon semiconductor substrate, a polycrystalline silicon layer or an amorphous silicon layer formed on an insulating layer formed on a substrate. A silicon oxide film can also be formed. Alternatively, a silicon oxide film may be formed on the surface of a silicon layer in an SOI structure, or a silicon element may be formed on a substrate on which a semiconductor element or a component of the semiconductor element is formed, or on a surface of a silicon layer formed thereon. An oxide film may be formed. Furthermore, a silicon oxide film may be formed on a surface of a silicon element formed on a substrate on which a semiconductor element or a component of the semiconductor element is formed, or a base insulating layer formed on the substrate. The heat treatment after the formation of the silicon oxide film is not essential and can be omitted in some cases.

Alternatively, after cleaning the surface of the silicon semiconductor substrate 40 with a 0.1% aqueous solution of hydrofluoric acid and pure water in Examples 1 to 13, the silicon semiconductor substrate 40 is transferred to a silicon oxide film forming apparatus. Although the wafer is carried in, the atmosphere from cleaning the surface of the silicon semiconductor substrate 40 to carrying it into the silicon oxide film forming apparatus may be an inert gas (eg, nitrogen gas) atmosphere. In addition, such an atmosphere
For example, the atmosphere of the apparatus for cleaning the surface of a silicon semiconductor substrate is set to an inert gas atmosphere, and the silicon semiconductor substrate 40 is placed in a transport box filled with an inert gas, and the substrate loading / unloading section 20 of the silicon oxide film forming apparatus. And processing room 50
64, and as shown in FIG. 64, a surface cleaning device, a silicon oxide film forming device, a transport path, a cluster tool device including a loader and an unloader, and a surface cleaning device for a silicon semiconductor substrate. From the substrate loading / unloading section 20 or the processing chamber 5 of the silicon oxide film forming apparatus
This can be achieved by connecting the surface cleaning apparatus and the atmosphere of the transfer path to an inert gas atmosphere.

Alternatively, instead of cleaning the surface of the silicon layer with a 0.1% aqueous solution of hydrofluoric acid and pure water,
Under the conditions exemplified in Table 2, the surface of the silicon layer may be cleaned by a gas phase cleaning method using anhydrous hydrogen fluoride gas. Note that methanol is added to prevent generation of particles. Alternatively, the surface of the silicon layer may be cleaned by a vapor phase cleaning method using hydrogen chloride gas under the conditions exemplified in Table 3. The atmosphere in the surface cleaning apparatus and the atmosphere in the transfer path before the start of the surface cleaning of the silicon layer or after the completion of the surface cleaning may be an inert gas atmosphere, for example, 1.3 × 10 ⁻¹ Pa (10 A vacuum atmosphere of about ^-3 Torr) may be used. When the atmosphere in the transfer path or the like is a vacuum atmosphere, the atmosphere in the substrate loading / unloading section 20 or the processing chamber 50 of the silicon oxide film forming apparatus when loading the silicon layer is set to, for example, 1.3 × 10 ^−1. Pa (10 ^-3
A vacuum atmosphere of about Torr may be set, and after the loading of the silicon layer is completed, the atmosphere of the substrate loading / unloading section 20 or the processing chamber 50 may be an atmosphere of an inert gas (for example, nitrogen gas) at atmospheric pressure.

[0190]

[Table 2] Anhydrous hydrogen fluoride gas: 300 sccm Methanol vapor: 80 sccm Nitrogen gas: 1000 sccm Pressure: 0.3 Pa Temperature: 60 ° C

[0191]

[Table 3] Hydrogen chloride gas / nitrogen gas: 1% by volume Temperature: 800 ° C

As the silicon oxide film forming apparatus in these cases, a silicon oxide film forming apparatus shown in FIGS. 13, 31, and 32 or FIGS. 65 and 66 described later can be used. As a result, the surface of the silicon layer terminated with hydrogen or fluorine before the formation of the silicon oxide film can be kept in a state free of contamination and the like, and as a result, moisture, organic substances, or Si It is possible to effectively prevent the characteristics of the formed silicon oxide film from deteriorating or generating a defective portion due to the incorporation of -OH.

FIG. 65 is a schematic cross-sectional view of a vertical type silicon oxide film forming apparatus which is slightly different from the vertical type silicon oxide film forming apparatus shown in FIG. The processing chamber 10 of this vertical type silicon oxide film forming apparatus includes an upper region 10A and a lower region 10B.
The ambient temperature of B is controlled by the heater 14. On the other hand, outside the upper region 10A, a plurality of lamps 14A that emit infrared light or visible light are arranged. Then, for example, in the same step as [Step-130] of Example 1, the surface of the silicon layer is oxidized using a wet gas while maintaining the atmosphere at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer. A first silicon oxide film forming step of forming a silicon oxide film is performed in the lower region 10 </ b> B of the processing chamber 10. At this time, the ambient temperature of the upper region 10A of the processing chamber 10 is maintained at 400 ° C. by the lamp 14A. Then, in the same step as [Step-140] of Example 1, introduction of the wet gas into the processing chamber 10 is stopped,
While an inert gas (for example, nitrogen gas) is introduced into the processing chamber 10 from the gas introduction unit 12, the ambient temperature of the upper region 10 </ b> A of the processing chamber 10 of the
The temperature is raised to the ambient temperature in the second silicon oxide film forming step by A, then the elevator mechanism 23 is operated to raise the quartz boat 24, and the silicon semiconductor substrate 40 is moved to the upper region 10A of the processing chamber 10. And
In a step similar to [Step-150] of the first embodiment, the silicon semiconductor substrate 40 is formed by a pyrogenic oxidation method.
A second silicon oxide film forming step of forming a silicon oxide film 42 on the surface of the substrate. Next, in the same step as [Step-160] in Example 1, the introduction of the wet gas was stopped, and an inert gas (for example, nitrogen gas) was introduced into the gas introduction unit 12.
The temperature of the atmosphere in the upper region 10A of the processing chamber 10 is increased by 850 ° C.
Heat up to Thereafter, an inert gas (for example, nitrogen gas) containing 0.1% by volume of hydrogen chloride gas is supplied to the gas introduction unit 12.
From the processing chamber 10 to the upper region 10 of the processing chamber 10.
In A, heat treatment is performed for 30 minutes.

Alternatively, FIG. 66 is a schematic cross-sectional view of a horizontal silicon oxide film forming apparatus slightly different from the horizontal silicon oxide film forming apparatus shown in FIG. The processing chamber 50 of this horizontal silicon oxide film forming apparatus is composed of a first region 50A and a second region 50B, and the ambient temperature of the first region 50A and the second region 50B are respectively set to the lamp 151A and the lamp 151A. 151B. Then, for example, in a step similar to [Step-720] of Example 7, the silicon layer is formed by an oxidation method using a wet gas while maintaining the atmosphere at a temperature at which silicon atoms are not desorbed from the surface of the silicon layer. A first silicon oxide film forming step of forming a silicon oxide film on the surface is performed. This silicon oxide film is formed in the first region 50A of the processing chamber 50. The control of the ambient temperature in the first region 50A is performed by the lamp 151A. At this time, the ambient temperature in the second region 50B of the processing chamber 50 is maintained at 400 ° C. by the lamp 151B. Then, in the same step as [Step-730] of Example 7, while continuing to introduce the wet gas into the processing chamber 50,
The ambient temperature in the second region 50B of the processing chamber 50 is raised to the ambient temperature in the second silicon oxide film forming step by the lamp 151B, and the silicon layer (for example, a silicon semiconductor substrate) is moved to the second region 50B. Then, in the same step as [Step-740], the second
The second silicon oxide film forming step of forming a silicon oxide film is further performed by an oxidation method using a wet gas in a state where the ambient temperature of the region 50B is kept at this temperature by the lamp 151B. Thereafter, in the same step as [Step-750], the introduction of the wet gas is stopped, and an inert gas (for example, nitrogen gas) is supplied from the gas introduction unit 54 to the processing chamber 50.
The temperature of the atmosphere in the second region 50B of the processing chamber 50 is raised to 850 ° C. by the lamp 151B while the gas is introduced into the inside. Next, an inert gas (for example, nitrogen gas) containing 0.1% by volume of hydrogen chloride gas is introduced into the processing chamber 50 from the gas introduction unit 54, and heat treatment is performed for 5 minutes. Incidentally, instead of the lamp in the silicon oxide film forming apparatus of FIG. 66, a resistance heater can be used in the same manner as shown in FIG.

Table 4 shows the atmosphere in the first silicon oxide film forming step (indicated as the first oxidation step in Table 4), the atmosphere in the temperature raising step, and the second In the silicon oxide film forming step (shown as a second oxidation step in Table 4), and in the step of raising the temperature for heat treatment of the formed silicon oxide film (in Table 4, the second heating step). (Indicated as a temperature step). Incidentally, regarding the second preferred embodiment of the present invention, except for the temperature raising step,
Table 4 shows the combinations of the atmosphere in the first silicon oxide film forming step, the atmosphere in the second silicon oxide film forming step, and the atmosphere in the step of raising the temperature for performing the heat treatment on the formed silicon oxide film. Can be the same as In Table 4, the wet gas atmosphere is described as “wet gas”, the wet gas atmosphere containing a halogen element is described as “* wet gas”, the inert gas atmosphere is described as “inert gas”, and the halogen element The inert gas atmosphere containing is denoted by “* inert gas”. Here, Table 4
The combinations of the various atmospheres shown in FIGS.
, A silicon oxide film forming apparatus shown in FIGS. 31, 32, and 66, or a combination thereof, and further, a cluster tool apparatus shown in FIGS. 58 and 64. can do. Also,
A wet gas atmosphere or a wet gas atmosphere containing a halogen element may be diluted with an inert gas.

[0196]

[Table 4] First oxidation step Heating step Second oxidation step Second heating step Wet gas Inert gas Wet gas Inert gas Wet gas Inert gas Wet gas * Inert gas Wet gas Inert gas * Wet gas Inert gas Wet gas Inert gas * Wet gas * Inert gas Wet gas * Inert gas Wet gas Inert gas Wet gas * Inert gas Wet gas * Inert gas Wet gas * Inert gas * Wet gas Non Active gas Wet gas * Inert gas * Wet gas * Inert gas Wet gas Wet gas Wet gas Inert gas Wet gas Wet gas Wet gas * Inert gas Wet gas Wet gas * Wet gas Inert gas Wet gas Wet gas * Wet Gas * Inert gas Wet gas * Wet gas Wet gas Inert gas Wet gas * Wet gas Wet gas * Inert gas Wet gas * Wet gas * Wet gas Inert gas S Wet gas * Wet gas * Wet gas * Inert gas * Wet gas Inert gas Wet gas Inert gas * Wet gas Inert gas Wet gas * Inert gas * Wet gas inert gas * Wet gas inert gas * Wet Gas Inert gas * Wet gas * Inert gas * Wet gas * Inert gas Wet gas Inert gas * Wet gas * Inert gas Wet gas * Inert gas * Wet gas * Inert gas * Wet gas Inert gas * Wet gas * Inert gas * Wet gas * Inert gas * Wet gas Wet gas Wet gas Inert gas * Wet gas Wet gas Wet gas * Inert gas * Wet gas Wet gas * Wet gas Inert gas * Wet gas Wet gas * Wet gas * Inert gas * Wet gas * Wet gas Wet gas Inert gas * Wet gas * Wet gas Wet gas * Inert gas * Wet gas * Wet gas * Wet Gas inert gas * wet gas * wet gas * wet gas * inert gas

[0197]

According to the method of forming a silicon oxide film of the present invention, the formation of a silicon oxide film on the surface of the silicon layer is started at an ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer. Since the formation of the silicon oxide film on the surface of the silicon layer is started at a temperature not lower than the temperature at which the gas does not condense on the surface of the silicon layer and not higher than 500 ° C., it is possible to prevent unevenness (roughness) from occurring on the surface of the silicon layer. . In addition, the finally formed silicon oxide film does not include a dry oxide film having low reliability, and a silicon oxide film having excellent characteristics can be formed. Therefore, a decrease in channel mobility can be prevented, the drive current of the MOS transistor element hardly deteriorates, and the occurrence of a stress leak phenomenon that causes deterioration of data retention characteristics in a flash memory or the like can be suppressed. It is possible to form a very thin, for example, gate oxide film having excellent long-term reliability. In addition, by forming an oxide film or a sacrificial oxide film for forming an element isolation region based on the method for forming a silicon oxide film of the present invention, the occurrence of unevenness at the interface between these oxide films and the silicon semiconductor substrate is suppressed. As a result, it is possible to more effectively prevent the electrical reliability of the gate oxide film from being lowered.

Further, according to the first preferred embodiment 1A of the present invention, in the state where the silicon oxide film which also functions as a protective film is already formed on the surface of the silicon layer, the atmosphere temperature is reduced to the second silicon oxide film formation. After the temperature is raised to the ambient temperature in the process, a silicon oxide film is further formed by an oxidation method using a wet gas, so that the surface of the silicon layer does not have irregularities (roughness) in the temperature raising process, and is excellent. A silicon oxide film having characteristics can be formed. As a result, it is possible to form an extremely thin gate oxide film having excellent long-term reliability. Alternatively, according to the preferred embodiment 1B of the present invention, the temperature variation in the plane of the silicon layer (for example, a silicon semiconductor substrate) can be reduced, so that the silicon oxide film is formed during the temperature rise. Even in this case, it is possible to suppress occurrence of in-plane thickness variation of the formed silicon oxide film. Furthermore, according to a second preferred embodiment of the present invention, the first
It is sufficient that the ambient temperature of the processing chamber and the second processing chamber is kept at a predetermined constant temperature, so that the temperature control in each processing chamber can be performed more accurately and the temperature stability in the treatment chamber is excellent. Therefore, the thickness controllability of the silicon oxide film is excellent. In addition, there is no reduction in throughput when forming the silicon oxide film. According to the third preferred embodiment of the present invention, the control range of the ambient temperature in the silicon oxide film forming apparatus can be narrowed, so that not only the ambient temperature can be controlled with high accuracy, but also from a high temperature to a low temperature. There is no need to cool the processing chamber, and the time required for forming the silicon oxide film can be reduced.

[Brief description of the drawings]

FIG. 1 is an atmosphere temperature profile in a method for forming a silicon oxide film according to a first or second embodiment of the present invention.

FIG. 2 is an atmosphere temperature profile in the method for forming a silicon oxide film according to the first or second embodiment of the present invention.

FIG. 3 is an atmosphere temperature profile in the first preferred embodiment of the present invention.

FIG. 4 is an atmosphere temperature profile in the first preferred embodiment of the present invention.

FIG. 5 is an atmosphere temperature profile in the first preferred embodiment of the present invention.

FIG. 6 is an atmosphere temperature profile in the first preferred embodiment of the present invention.

FIG. 7 is an atmosphere temperature profile in the first preferred embodiment of the present invention.

FIG. 8 is an atmosphere temperature profile in a second preferred embodiment of the present invention.

FIG. 9 is an atmosphere temperature profile in a second preferred embodiment of the present invention.

FIG. 10 is an atmosphere temperature profile in a second preferred embodiment of the present invention.

FIG. 11 is an atmosphere temperature profile in a second preferred embodiment of the present invention.

FIG. 12 is a schematic partial cross-sectional view of a silicon semiconductor substrate and the like for describing a method for forming a silicon oxide film of Example 1.

FIG. 13 is a schematic sectional view of a vertical type silicon oxide film forming apparatus (thermal oxidation furnace).

FIG. 14 is an atmosphere temperature profile in Example 1.

FIG. 15 is a schematic sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 1.

FIG. 16 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for explaining a method of forming a silicon oxide film in Example 1, following FIG.

FIG. 17 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 1, following FIG. 16;

FIG. 18 is an atmosphere temperature profile in Example 2.

FIG. 19 is a schematic diagram of a circuit for measuring a time-dependent dielectric breakdown (TDDB) characteristic.

FIG. 20 is a diagram showing a Weibull probability distribution showing evaluation results of a time-dependent dielectric breakdown (TDDB) characteristic of a silicon oxide film formed by the method described in Example 1 and Comparative Example.

FIG. 21 is a diagram showing a Weibull probability distribution showing evaluation results of a time-dependent dielectric breakdown (TDDB) characteristic of a silicon oxide film formed by the method described in Example 2 and Comparative Example.

FIG. 22 is a diagram showing a Weibull probability distribution showing evaluation results of a time-dependent dielectric breakdown (TDDB) characteristic of a silicon oxide film formed by the method described in Example 3 and Comparative Example.

FIG. 23 shows a MOS manufactured in Example 1 and Example 4.
The value of Q _BD at a cumulative failure rate of the capacitor of 50%, the amount of desorbed hydrogen atoms from the surface of the silicon semiconductor substrate,
5 is a graph showing a relationship between ambient temperatures in a first silicon oxide film forming step.

FIG. 24 is an atmosphere temperature profile in Example 5.

FIG. 25 is a schematic sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 5.

FIG. 26 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method for forming a silicon oxide film in Example 5, following FIG. 25;

FIG. 27 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 5, following FIG. 26;

FIG. 28 is a schematic sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 6.

FIG. 29 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 6, following FIG. 28;

FIG. 30 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for explaining a method of forming a silicon oxide film in Example 6, following FIG. 29;

FIG. 31 is a schematic cross-sectional view of a horizontal silicon oxide film forming apparatus suitable for carrying out a silicon oxide film forming method according to a second embodiment of the present invention.

FIG. 32 is a second embodiment of the present invention, which is slightly different in structure from FIG. 31;
FIG. 5 is a schematic cross-sectional view of a horizontal silicon oxide film forming apparatus suitable for performing the method of forming a silicon oxide film according to the embodiment.

FIG. 33 is a schematic partial cross-sectional view of a silicon semiconductor substrate and the like for describing a method of forming a silicon oxide film of Example 8.

FIG. 34 is a conceptual diagram of a batch type vertical silicon oxide film forming apparatus suitable for carrying out Example 8.

35 is a schematic cross-sectional view of a portion including a first processing chamber of the batch-type vertical silicon oxide film forming apparatus shown in FIG.

36 is a schematic sectional view of a portion including a second processing chamber of the batch-type vertical silicon oxide film forming apparatus shown in FIG. 34.

FIG. 37 is an atmosphere temperature profile in Example 8.

FIG. 38 is a schematic sectional view of a silicon oxide film forming apparatus and the like for describing a method for forming a silicon oxide film in Example 8.

FIG. 39 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 8 following FIG. 38;

FIG. 40 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 8 following FIG. 39;

FIG. 41 is a schematic sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 8 following FIG. 40;

FIG. 42 is a schematic sectional view of a silicon oxide film forming apparatus and the like for explaining a method of forming a silicon oxide film in Example 8 following FIG. 41;

FIG. 43 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 8 following FIG. 42;

FIG. 44 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 8 following FIG. 43;

FIG. 45 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 8 following FIG. 44;

FIG. 46 is a schematic sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 8 following FIG. 45;

FIG. 47 is a conceptual diagram of a batch type vertical silicon oxide film forming apparatus suitable for carrying out Embodiment 9.

FIG. 48 is a schematic sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9.

FIG. 49 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 48;

FIG. 50 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 49;

FIG. 51 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 50;

FIG. 52 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 51;

FIG. 53 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 52;

FIG. 54 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 53;

FIG. 55 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 54;

FIG. 56 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 55;

FIG. 57 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 9 following FIG. 56;

FIG. 58 is a conceptual diagram of a silicon oxide film forming apparatus suitable for implementing the tenth embodiment.

FIG. 59 is a schematic sectional view of a batch type furnace annealing apparatus in a silicon oxide film forming apparatus suitable for carrying out Example 10.

FIG. 60 is an atmosphere temperature profile in Examples 11 and 12.

FIG. 61 is a schematic sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 11.

FIG. 62 is a schematic sectional view of a silicon oxide film forming apparatus and the like for explaining a method of forming a silicon oxide film in Example 11 following FIG. 61;

FIG. 63 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a method of forming a silicon oxide film in Example 11 following FIG. 62;

FIG. 64 is a schematic view of a cluster tool device.

FIG. 65 is a schematic sectional view of a vertical type silicon oxide film forming apparatus having a slightly different type from the vertical type silicon oxide film forming apparatus shown in FIG. 13;

FIG. 66 is a schematic sectional view of a horizontal silicon oxide film forming apparatus having a slightly different form from the horizontal silicon oxide film forming apparatus shown in FIG. 32;

FIG. 67 is a schematic sectional view of a silicon oxide film forming apparatus or the like for describing a conventional method of forming a silicon oxide film.

FIG. 68 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for illustrating a conventional method of forming a silicon oxide film, following FIG. 67;

FIG. 69 is a schematic cross-sectional view of a silicon oxide film forming apparatus and the like for describing a conventional method of forming a silicon oxide film, following FIG. 68;

[Explanation of symbols]

10, 110, 210 ... processing chamber, 11, 111, 2
11 ... gas flow path, 12, 112, 212 ... gas introduction part, 13, 113, 213 ... gas exhaust part, 1
4, 114, 214 ... heater, 15, 115, 21
Reference numeral 5: shutter, 16, 116, 216: heat equalizing tube, 20: substrate loading / unloading part, 21, 121: gas introduction part, 22, 122: gas exhaust part, 23, 123
... Elevator mechanism, 24,124 ... Quartz boat, 30,130 ... Combustion chamber, 31,131 ... Piping, 40 ... Silicon semiconductor substrate, 41 ... Element isolation region, 42 ..Silicon oxide film, 43 gate electrode, 50 processing chamber, 51 resistance heater,
51A, 151A, 151B ... lamp, 52 ...
Wafer table, 53 gate valve, 54 gas introduction unit, 55 gas exhaust unit, 120, 120A, 12
0B, 301: transport path, 125, 125A, 125
B: door, 126: shutter, 301: loader / unloader, 302, 303: processing device, 304: furnace annealing device

 ──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 9-90766 (32) Priority date Hei 9 (1997) April 9 (33) Priority claim country Japan (JP) (31) Priority Claim No. Hei 9-112338 (32) Priority date Hei 9 (1997) April 30 (33) Priority claim country Japan (JP) (31) Priority claim number Patent application Hei 9-278977 (32) Priority Japan, Japan (JP) (72) Inventor Hideki Kimura 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Toyotaka Kataoka 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo, Japan (72) Inventor Atsushi Suzuki 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Shin Tanaka History Sony 7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (100)

[Claims] An oxidation method using a wet gas starts formation of a silicon oxide film on the surface of the silicon layer at an ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer. Forming a silicon oxide film until a desired thickness is obtained by a method. 2. The method according to claim 1, wherein the ambient temperature at which silicon atoms do not desorb from the surface of the silicon layer is a temperature at which bonds between atoms terminating at the surface of the silicon layer and silicon atoms are not broken. The method for forming a silicon oxide film according to the above. 3. The silicon oxide film according to claim 2, wherein the ambient temperature at which silicon atoms do not desorb from the surface of the silicon layer is a temperature at which Si—H bonds on the surface of the silicon layer are not broken. Forming method. 4. The silicon oxide film according to claim 2, wherein the ambient temperature at which silicon atoms do not desorb from the surface of the silicon layer is a temperature at which Si—F bonds on the surface of the silicon layer are not broken. Forming method. 5. The oxidation method using a wet gas is generated by a pyrogenic oxidation method, an oxidation method using water vapor generated by heating pure water, and bubbling heated pure water with an oxygen gas or an inert gas. 2. The method for forming a silicon oxide film according to claim 1, wherein at least one of the oxidation methods using steam is used. 6. The atmosphere temperature when the formation of a silicon oxide film having a desired thickness is completed is higher than the atmosphere temperature when the formation of a silicon oxide film on the surface of the silicon layer is started. Item 3. The method for forming a silicon oxide film according to Item 1. 7. The method according to claim 1, wherein after the formation of the silicon oxide film having a desired thickness is completed, a heat treatment is performed on the formed silicon oxide film. 8. The method for forming a silicon oxide film according to claim 7, wherein the atmosphere of the heat treatment is an inert gas atmosphere containing a halogen element. 9. The method for forming a silicon oxide film according to claim 8, wherein the halogen element is chlorine. 10. The silicon oxide film according to claim 9, wherein chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 11. The method according to claim 7, wherein the heat treatment is performed at a temperature of 700 to 950 ° C. 12. The method according to claim 11, wherein the heat treatment is a furnace annealing treatment. 13. The method according to claim 7, wherein the temperature of the atmosphere when performing the heat treatment on the formed silicon oxide film is higher than the temperature when the formation of the silicon oxide film having a desired thickness is completed. The method for forming a silicon oxide film according to the above. 14. After the formation of a silicon oxide film having a desired thickness is completed, the atmosphere is switched to an inert gas atmosphere containing a halogen element, and then the temperature is raised to an ambient temperature for performing heat treatment. The method for forming a silicon oxide film according to claim 13, wherein: 15. The method according to claim 14, wherein the halogen element is chlorine. 16. The silicon oxide film according to claim 15, wherein chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 17. An atmosphere before forming a silicon oxide film is an inert gas atmosphere.
3. The method for forming a silicon oxide film according to item 1. 18. A method of forming a silicon oxide film, comprising: before forming a silicon oxide film, cleaning the surface of the silicon layer, without exposing the silicon layer after the surface cleaning to the atmosphere. Item 3. The method for forming a silicon oxide film according to Item 1. 19. A silicon oxide film is formed on the surface of the silicon layer by an oxidation method using a wet gas at an ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer. A first silicon oxide film forming step of forming a silicon oxide film while maintaining an atmosphere in a temperature range in which silicon atoms are not desorbed from the surface of the layer; 2. The method according to claim 1, further comprising a second silicon oxide film forming step of further forming a silicon oxide film until a desired thickness is obtained by an oxidation method using a wet gas at a high ambient temperature. Of forming a silicon oxide film. 20. The method according to claim 19, wherein the ambient temperature at which the silicon atoms do not desorb from the surface of the silicon layer is a temperature at which the bond between the atoms terminating the silicon layer surface and the silicon atoms is not broken. The method for forming a silicon oxide film according to the above. 21. An atmosphere temperature at which silicon atoms are not desorbed from the surface of the silicon layer is a temperature at which Si—H bonds on the surface of the silicon layer are not broken.
0. A method for forming a silicon oxide film according to item 0. 22. An ambient temperature at which silicon atoms are not desorbed from the surface of the silicon layer is a temperature at which Si—F bonds on the surface of the silicon layer are not broken.
0. A method for forming a silicon oxide film according to item 0. 23. An oxidation method using a wet gas in the first silicon oxide film forming step, the second silicon oxide film forming step, or the first silicon oxide film forming step and the second silicon oxide film forming step. Is a pyrogenic oxidation method, an oxidation method using steam generated by heating pure water, and
20. An oxidation method using at least one of the oxidation methods using steam generated by bubbling heated pure water with an oxygen gas or an inert gas.
3. The method for forming a silicon oxide film according to item 1. 24. A halogen gas is contained in the wet gas in the first silicon oxide film forming step, the second silicon oxide film forming step, or the first silicon oxide film forming step and the second silicon oxide film forming step. The method for forming a silicon oxide film according to claim 23, wherein the silicon oxide film is contained. 25. The method according to claim 24, wherein the halogen element is chlorine. 26. The silicon oxide film according to claim 25, wherein the chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the wet gas is 0.02 to 10% by volume. Forming method. 27. A wet gas in the first silicon oxide film forming step, the second silicon oxide film forming step, or the first silicon oxide film forming step and the second silicon oxide film forming step is an inert gas. The method for forming a silicon oxide film according to claim 19, wherein the silicon oxide film is diluted. 28. A silicon oxide film forming apparatus having one processing chamber for forming a silicon oxide film, wherein a first silicon oxide film forming step and a second silicon oxide film forming step are performed in the processing chamber. The method according to claim 19, wherein the method is performed. 29. A first silicon oxide film forming step and a second
The method for forming a silicon oxide film according to claim 28, wherein the step of forming a silicon oxide film is performed by a batch method. 30. The processing chamber is provided with heating means for heating the silicon layer, which is provided outside the processing chamber and substantially parallel to the surface of the silicon layer. 3. The film forming step and the second silicon oxide film forming step are performed in a single wafer process.
9. The method for forming a silicon oxide film according to item 8. 31. The method for forming a silicon oxide film according to claim 28, further comprising a temperature raising step between the first silicon oxide film forming step and the second silicon oxide film forming step. 32. The method for forming a silicon oxide film according to claim 31, wherein the atmosphere in the temperature raising step is an inert gas atmosphere or an oxidizing atmosphere containing a wet gas. 33. The method according to claim 32, wherein the atmosphere in the temperature raising step contains a halogen element. 34. The method according to claim 33, wherein the halogen element is chlorine. 35. Chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in an inert gas or a wet gas is 0.1%.
35. The composition according to claim 34, wherein the content is 02 to 10% by volume.
3. The method for forming a silicon oxide film according to item 1. 36. The method according to claim 31, wherein the atmosphere in the temperature raising step is an oxidizing atmosphere containing a wet gas diluted with an inert gas. 37. A first processing chamber and a second processing chamber for forming a silicon oxide film, and a first processing chamber and a second processing chamber for forming a silicon oxide film.
The first silicon oxide film forming step is performed in the first processing chamber using a silicon oxide film forming apparatus provided with a transfer path connecting the first processing chamber to the first processing chamber. 20. The method for forming a silicon oxide film according to claim 19, wherein the silicon oxide film is carried into the second processing chamber via the second processing chamber, and then the second silicon oxide film forming step is performed in the second processing chamber. 38. The method for forming a silicon oxide film according to claim 37, wherein the silicon layer is transferred from the first processing chamber to the second processing chamber via a transfer path without being exposed to the atmosphere. . 39. The atmosphere temperature in the transfer path when transferring the silicon layer from the first processing chamber to the second processing chamber is substantially equal to the atmospheric temperature in the first processing chamber in the first silicon oxide film forming step. The method for forming a silicon oxide film according to claim 38, wherein the values are made equal. 40. A first step of forming a silicon oxide film and a step of forming a second silicon oxide film.
The method for forming a silicon oxide film according to claim 37, wherein the step of forming a silicon oxide film is performed by a batch method. 41. The silicon oxide film according to claim 37, wherein the first silicon oxide film forming step is performed by a single wafer type, and the second silicon oxide film forming step is performed by a batch type. Forming method. 42. A first silicon oxide film forming step and a second
The method for forming a silicon oxide film according to claim 37, wherein the step of forming a silicon oxide film is performed by a single wafer method. 43. A silicon oxide film forming apparatus in which a shutter is provided between a portion of the transfer path communicating with the first processing chamber and a portion of the transfer path communicating with the second processing chamber. The method for forming a silicon oxide film according to claim 37, wherein 44. The method according to claim 19, wherein after the second silicon oxide film forming step is completed, a heat treatment is performed on the formed silicon oxide film. 45. The atmosphere for the heat treatment is an inert gas atmosphere containing a halogen element.
5. The method for forming a silicon oxide film according to 4. 46. The method according to claim 45, wherein the halogen element is chlorine. 47. The silicon oxide film according to claim 46, wherein the chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 48. The method according to claim 44, wherein the heat treatment is performed at a temperature of 700 to 950 ° C. 49. The method for forming a silicon oxide film according to claim 48, wherein the heat treatment is a furnace annealing process. 50. An atmosphere temperature when performing heat treatment on the formed silicon oxide film is higher than an atmosphere temperature when forming the silicon oxide film in the second silicon oxide film forming step. 45. The method for forming a silicon oxide film according to 44. 51. After the completion of the second silicon oxide film forming step, the atmosphere is switched to an inert gas atmosphere containing a halogen element, and then the temperature is raised to an ambient temperature for performing heat treatment. A method for forming a silicon oxide film according to claim 50. 52. The method for forming a silicon oxide film according to claim 51, wherein the halogen element is chlorine. 53. The silicon oxide film according to claim 52, wherein the chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 54. The method according to claim 44, wherein the atmosphere for the heat treatment is a nitrogen-based gas atmosphere. 55. The method for forming a silicon oxide film according to claim 19, wherein in the first silicon oxide film forming step, the atmosphere before forming the silicon oxide film is an inert gas atmosphere. 56. A step of cleaning the surface of the silicon layer before the step of forming the first silicon oxide film, wherein the step of forming the first silicon oxide film is performed without exposing the silicon layer after the surface cleaning to the atmosphere. The method for forming a silicon oxide film according to claim 19, wherein: 57. An atmosphere temperature when the formation of a silicon oxide film having a desired thickness is completed is within an atmosphere temperature range in which silicon atoms are not desorbed from the surface of the silicon layer. The method for forming a silicon oxide film according to the above. 58. The method according to claim 57, wherein after the formation of the silicon oxide film having a desired thickness is completed, a heat treatment is performed on the formed silicon oxide film. 59. The heat treatment atmosphere is an inert gas atmosphere containing a halogen element.
9. The method for forming a silicon oxide film according to item 8. 60. The method according to claim 59, wherein the halogen element is chlorine. 61. The silicon oxide film according to claim 60, wherein chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 62. The method according to claim 58, wherein the heat treatment is performed at a temperature of 700 to 950 ° C. 63. The method for forming a silicon oxide film according to claim 62, wherein the heat treatment is a furnace annealing process. 64. The method of forming a silicon oxide film according to claim 1, wherein the atmosphere temperature when the formation of the silicon oxide film having a desired thickness is completed is 500 ° C. or less. 65. The method according to claim 1, wherein the silicon layer comprises an epitaxial silicon layer formed on the substrate. 66. The method according to claim 1, wherein the silicon oxide film is a gate oxide film. 67. The silicon layer is composed of a silicon semiconductor substrate, and the silicon oxide film is an oxide film formed on the silicon semiconductor substrate before forming a gate oxide film on the surface of the silicon semiconductor substrate. 2. The method for forming a silicon oxide film according to item 1. 68. The oxide film formed on the silicon semiconductor substrate before the gate oxide film is formed on the surface of the silicon semiconductor substrate is an oxide film for forming an element isolation region. Of forming a silicon oxide film. 69. The method according to claim 68, wherein the element isolation region has a LOCOS structure, a trench structure, or a LOCOS structure and a trench structure. 70. The method according to claim 67, wherein the oxide film formed on the silicon semiconductor substrate before the gate oxide film is formed on the surface of the silicon semiconductor substrate is a sacrificial oxide film. . 71. The formation of a silicon oxide film on the surface of the silicon layer by an oxidation method using a wet gas is started at an atmosphere temperature of 500 ° C. or more at a temperature at which the wet gas does not dew on the surface of the silicon layer. A method for forming a silicon oxide film, wherein the silicon oxide film is formed to a desired thickness by an oxidation method using a gas. 72. Starting the formation of a silicon oxide film on the surface of the silicon layer by an oxidation method using a wet gas at an ambient temperature of not less than a temperature at which the wet gas does not dew on the silicon layer surface and not more than 450 ° C. The method for forming a silicon oxide film according to claim 71, characterized in that: 73. A method for starting formation of a silicon oxide film on the surface of a silicon layer by an oxidation method using a wet gas at an ambient temperature of 400 ° C. or more and a temperature at which the wet gas does not dew on the surface of the silicon layer. The method for forming a silicon oxide film according to claim 72, characterized in that: 74. An oxidation method using a wet gas is generated by a pyrogenic oxidation method, an oxidation method using water vapor generated by heating pure water, and bubbling heated pure water with an oxygen gas or an inert gas. 72. The method for forming a silicon oxide film according to claim 71, wherein the method is at least one of the oxidation methods using steam. 75. An atmosphere temperature when forming a silicon oxide film having a desired thickness is completed is higher than an atmosphere temperature when starting formation of a silicon oxide film on a surface of a silicon layer. Item 71. The method for forming a silicon oxide film according to Item 71. 76. The method according to claim 71, wherein after the formation of the silicon oxide film having a desired thickness is completed, a heat treatment is performed on the formed silicon oxide film. 77. The atmosphere for the heat treatment is an inert gas atmosphere containing a halogen element.
7. The method for forming a silicon oxide film according to 6. 78. The method according to claim 77, wherein the halogen element is chlorine. 79. The silicon oxide film according to claim 78, wherein the chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 80. The method according to claim 76, wherein the heat treatment is performed at a temperature of 700 to 950 ° C. 81. The method for forming a silicon oxide film according to claim 80, wherein the heat treatment is a furnace annealing process. 82. The atmosphere temperature when the heat treatment is performed on the formed silicon oxide film is higher than the atmosphere temperature when the formation of the silicon oxide film having a desired thickness is completed. The method for forming a silicon oxide film according to the above. 83. After the formation of a silicon oxide film having a desired thickness is completed, the atmosphere is switched to an inert gas atmosphere containing a halogen element, and then the temperature is raised to an ambient temperature for performing a heat treatment. The method for forming a silicon oxide film according to claim 82, wherein: 84. The method according to claim 83, wherein the halogen element is chlorine. 85. The silicon oxide film according to claim 84, wherein chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 86. The method of forming a silicon oxide film according to claim 71, wherein the ambient temperature when forming the silicon oxide film having a desired thickness is completed is 500 ° C. or lower. 87. The method according to claim 86, wherein after the formation of the silicon oxide film having a desired thickness is completed, a heat treatment is performed on the formed silicon oxide film. 88. The heat treatment atmosphere is an inert gas atmosphere containing a halogen element.
8. The method for forming a silicon oxide film according to 7. 89. The method according to claim 88, wherein the halogen element is chlorine. 90. The silicon oxide film according to claim 89, wherein chlorine is in the form of hydrogen chloride, and the concentration of hydrogen chloride contained in the inert gas is 0.02 to 10% by volume. Formation method. 91. The method according to claim 87, wherein the heat treatment is performed at a temperature of 700 to 950 ° C. 92. The method for forming a silicon oxide film according to claim 91, wherein the heat treatment is a furnace annealing treatment. 93. An atmosphere before forming a silicon oxide film is an inert gas atmosphere.
2. The method for forming a silicon oxide film according to item 1. 94. A process for cleaning a surface of a silicon layer before forming a silicon oxide film, wherein the silicon oxide film is formed without exposing the silicon layer after the surface cleaning to the atmosphere. Item 71. The method for forming a silicon oxide film according to Item 71. 95. The method according to claim 71, wherein the silicon layer comprises an epitaxial silicon layer formed on the substrate. 96. The method according to claim 71, wherein the silicon oxide film is a gate oxide film. 97. The silicon layer is composed of a silicon semiconductor substrate, and the silicon oxide film is an oxide film formed on the silicon semiconductor substrate before forming a gate oxide film on the surface of the silicon semiconductor substrate. 72. The method for forming a silicon oxide film according to 71. 98. The oxide film formed on the silicon semiconductor substrate before forming the gate oxide film on the surface of the silicon semiconductor substrate is an oxide film for forming an element isolation region. Of forming a silicon oxide film. 99. The method according to claim 98, wherein the element isolation region has a LOCOS structure, a trench structure, or a LOCOS structure and a trench structure. 100. The method according to claim 97, wherein the oxide film formed on the silicon semiconductor substrate before forming the gate oxide film on the surface of the silicon semiconductor substrate is a sacrificial oxide film. .