JP2002176050A - Method of forming silicon oxide film and system thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming a silicon oxide film of good quality on the surface of a silicon wafer by oxidizing the silicon wafer at a low temperature in the formation of the silicon oxide film on the surface of the wafer in the manufacturing process of a semiconductor element and to provide a silicon oxide film manufacturing system. SOLUTION: In a method of forming a silicon oxide film and a silicon oxide film manufacturing system, a solid dielectric is installed on the counter surface of the electrode on at least one side of a pair of counter electrodes under the pressure in the vicinity of the atmospheric pressure, oxygen-containing gas is introduced between the pair of the counter electrodes to apply a pulse-shaped electric field to the gas, whereby an obtainable plasma is brought into contact with a silicon wafer and the silicon oxide film is formed on the surface of the wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a silicon oxide film on a silicon wafer surface by oxidizing the surface of the silicon wafer by a normal pressure plasma method.

[0002]

2. Description of the Related Art Generally, a general structure of a semiconductor device is that a gate electrode, a gate insulating film, a silicon film, a source insulator, a drain insulating film, a source electrode, a drain electrode, a passivation film (protective film) are formed on a substrate. And so on. Here, the substrate is made of a glass substrate or a wafer substrate, the electrodes are made of a metal or a metal compound such as Al or Cu, and the interlayer insulator including the passivation film is silicon oxide, silicon nitride, or the like. It is made of silicon carbide or the like, and the silicon layer is made of a material such as a Si single crystal layer, an a-Si layer, and a-Si doped with P, B, As, Ge, or the like.

A semiconductor element is manufactured by combining these materials in accordance with required functions, but it can be said that it mainly consists of a combination of repeated heat treatment steps. In particular, furnaces are widely used mainly in the heat treatment process in the VLSI manufacturing process, and formation of a thermal oxide film is one of the most important technologies in the heat treatment process. It has been said that the ability to uniformly form this thermal oxide film with high quality is the starting point of VLSI manufacturing.

[0004] However, when various treatments are performed by repeating the heat treatment, the base material must endure the heat cycle, and the result of the treatment so far does not fluctuate in the subsequent heat treatment. Inevitably, the temperature must be lowered as much as possible to reduce the effect of such a kind of thermal shock.

[0005] At present, the process obstructing the total low temperature is mainly a silicon oxidation process. PECVD, sputtering, liquid layer deposition, etc. have been developed as low-temperature technologies that replace the current mainstream thermal oxidation at around 1000 ° C, but have the disadvantage that the interface properties between silicon and oxide films are not excellent. ing. In addition, a method of oxidizing the silicon surface with ozone gas, a method of oxidizing by exciting active oxygen by ultraviolet light, and a method of oxidizing by oxidizing active oxygen by plasma have been developed. Has the disadvantage that the interfacial characteristics cannot be obtained.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a method for forming a silicon oxide film on a surface of a silicon wafer in a semiconductor device manufacturing process. It is an object of the present invention to provide a method and an apparatus for forming a silicon oxide film.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by using a normal-pressure plasma method capable of realizing a stable discharge state under atmospheric pressure conditions, the present invention has been developed under a low temperature. The present inventors have found that a good quality silicon oxide film can be easily formed on the surface of a silicon wafer, and have completed the present invention.

That is, according to a first aspect of the present invention, a solid dielectric is provided on at least one of the opposing surfaces of a pair of electrodes facing each other under a pressure near the atmospheric pressure, and an oxygen-containing material is provided between the pair of electrodes. This is a method in which plasma obtained by introducing a gas and applying a pulsed electric field is brought into contact with a silicon wafer to form a silicon oxide film on the surface of the silicon wafer.

A second invention of the present invention is the method for forming a silicon oxide film according to the first invention, wherein the oxygen-containing gas contains oxygen gas at 4% by volume or more.

According to a third aspect of the present invention, the pulse-like electric field has a pulse rise and / or fall time of 100 μs or less and an electric field intensity of 0.5 to 250 kV / cm.
A method for forming a silicon oxide film according to the first or second invention, characterized in that:

According to a fourth aspect of the present invention, the pulse-like electric field has a frequency of 0.5 to 100 kHz and a pulse duration of 1 to 1000 μs.
A method for forming a silicon oxide film according to any one of the inventions.

According to a fifth aspect of the present invention, there is provided a pair of opposing electrodes having a solid dielectric disposed on at least one opposing surface, a mechanism for introducing a processing gas between the pair of opposing electrodes,
An apparatus for forming a silicon oxide film on a silicon wafer surface, comprising: a mechanism for applying a pulsed electric field between the electrodes; and a mechanism for bringing plasma obtained by the pulsed electric field into contact with a silicon wafer.

According to a sixth aspect of the present invention, the mechanism for bringing the plasma into contact with the silicon wafer is such that the plasma generated between the opposing electrodes is guided toward the silicon wafer through a solid dielectric having a gas outlet nozzle. According to a fifth aspect of the present invention, there is provided the apparatus for forming a silicon oxide film.

According to a seventh aspect of the present invention, the mechanism for bringing the plasma into contact with the silicon wafer is characterized in that the plasma generated between the counter electrodes through the solid dielectric having a gas outlet nozzle after the preliminary discharge is directed toward the silicon wafer. An apparatus for forming a silicon oxide film according to the fifth or sixth aspect of the present invention, wherein the apparatus is configured to guide the silicon oxide film.

According to an eighth aspect of the present invention, there is provided an apparatus for forming a silicon oxide film comprising the apparatus according to any one of the fifth to seventh aspects and a silicon wafer transport mechanism.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and an apparatus for forming a silicon oxide film on the surface of a silicon wafer for a semiconductor device by a normal pressure plasma method.
A gas is obtained by disposing a solid dielectric on at least one of the opposed surfaces of a pair of opposed electrodes, introducing a processing gas between the pair of opposed electrodes, and applying a pulsed electric field between the electrodes. Is to form a silicon oxide film on the silicon wafer by contacting the plasma with the silicon wafer. Hereinafter, the present invention will be described in detail.

The above-mentioned pressure near the atmospheric pressure means 1.333
× 10 ^{4 to} 10.664 × 10 ⁴ Pa.
Above all, pressure adjustment is easy and the device is simple 9.33
The range of 1 × 10 ^{4 to} 10.297 × 10 ⁴ Pa is preferable.

As the processing gas for forming the silicon oxide film of the present invention, a gas that generates oxygen radicals is used to promote surface oxidation. Examples of the radical that contributes to the oxidation reaction include an oxygen molecule, an excited oxygen molecule, an oxygen molecule ion, an oxygen atom, an oxygen atom ion, an excited ozone molecule, an ozone molecule ion, and the like. As a source of these, any oxygen-containing gas may be used, and in addition to oxygen, carbon monoxide, carbon dioxide, air, water vapor, and the like can also be used. The introduction of the oxygen-containing gas into the plasma is particularly effective for surface oxidation.

The processing gas of the present invention is preferably a gas containing 4% by volume or more, preferably 4 to 30% by volume of oxygen, whereby high-density plasma can be generated and high-speed processing can be performed. Becomes 4% oxygen by volume
If it is less than this, high-concentration oxygen plasma cannot be realized. The treatment can be carried out even if the oxygen content exceeds 30% by volume, but the effect is hardly changed. Therefore, the following diluent gas may be used in terms of economy, handling, and safety.

As the diluent gas, argon, neon, xenon, helium, nitrogen, dry air (the oxygen content when air is used is the value including oxygen in the air) and the like can be used. These may be used alone or in combination of two or more. In consideration of the balance between the processing effect, economy, and handleability, a processing gas comprising oxygen and argon, nitrogen, or air is preferable.

Conventionally, treatment has been performed in the presence of helium at a pressure close to the atmospheric pressure. However, according to the method of applying a pulsed electric field of the present invention, the method is less expensive than helium. Stable processing in nitrogen and argon is possible.

Examples of the above-mentioned electrode include those made of a simple metal such as copper and aluminum, alloys such as stainless steel and brass, and intermetallic compounds. The shape of the electrodes is not particularly limited, but is preferably a structure in which the distance between the opposing electrodes is constant in order to avoid the occurrence of arc discharge due to electric field concentration. Examples of the electrode structure that satisfies this condition include a parallel plate type, a cylindrical opposed plate type, a spherical opposed plate type, a hyperbolic opposed plate type, and a coaxial cylindrical structure.

In addition, other than the substantially constant structure, a cylindrically opposed cylindrical type having a large cylindrical curvature can be used as a counter electrode because the degree of electric field concentration causing arc discharge is small. The curvature is preferably at least 20 mm in radius. Although it depends on the dielectric constant of the solid dielectric, at a curvature smaller than that, arc discharge due to electric field concentration tends to concentrate. If the respective curvatures are greater than this, the curvatures of the opposing electrodes may be different. The larger the curvature, the closer to the flat plate, the more stable the discharge can be obtained. Therefore, the radius is more preferably 40 mm or more.

Furthermore, the electrodes for generating plasma only need to have a solid dielectric disposed on at least one of the pair. Even if the pair of electrodes face each other at an appropriate distance so as not to cause a short circuit. Well, they may be orthogonal.

The solid dielectric is provided on one or both of the opposing surfaces of the electrodes. At this time, it is preferable that the solid dielectric and the electrode on the side to be installed are in close contact with each other and completely cover the opposing surface of the contacting electrode. This is because if there is a portion where the electrodes directly face each other without being covered by the solid dielectric, an arc discharge is likely to occur therefrom.

The solid dielectric may be in the form of a sheet or a film, and preferably has a thickness of 0.01 to 4 mm. If it is too thick, a high voltage may be required to generate discharge plasma, and if it is too thin, dielectric breakdown may occur when a voltage is applied, and arc discharge may occur. As the shape of the solid dielectric, a container type can be used.

Examples of the material of the solid dielectric include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxides such as silicon dioxide, aluminum oxide, zirconium dioxide and titanium dioxide, and double oxides such as barium titanate. And those obtained by layering them.

In particular, it is preferable that the solid dielectric has a relative dielectric constant of 2 or more (the same applies under a 25 ° C. environment). Specific examples of the dielectric having a relative dielectric constant of 2 or more include polytetrafluoroethylene, glass, and a metal oxide film. In order to stably generate a high-density discharge plasma, it is preferable to use a fixed dielectric having a relative dielectric constant of 10 or more. Although the upper limit of the relative permittivity is not particularly limited, it is known that the actual material is about 18,500. As a solid dielectric having a relative dielectric constant of 10 or more, for example, a metal oxide film mixed with 5 to 50% by weight of titanium oxide and 50 to 95% by weight of aluminum oxide, or a metal oxide film containing zirconium oxide It is preferable to use a film having a thickness of 10 to 1000 μm.

The distance between the electrodes is determined by the thickness of the solid dielectric,
It is appropriately determined in consideration of the magnitude of the applied voltage, the purpose of utilizing the plasma, and the like, and is preferably 1 to 50 mm. If it is less than 1 mm, it may not be sufficient to place the electrodes at intervals. If it exceeds 50 mm, it is difficult to generate uniform discharge plasma.

The pulse electric field of the present invention will be described. FIG. 1 shows an example of a pulse voltage waveform. The waveforms (a) and (b) are impulse waveforms, the waveform (c) is a pulse waveform, and the waveform (d) is a modulation waveform. Although FIG. 1 shows a case where the voltage application is repeated positive and negative, a pulse of a type that applies a voltage to either the positive or negative polarity side may be used. Also,
A pulse electric field on which a direct current is superimposed may be applied. The waveform of the pulse electric field in the present invention is not limited to the above-mentioned waveforms, and may be modulated using pulses having different pulse shapes, rise times, and frequencies. Such modulation is suitable for performing high-speed continuous surface treatment.

The rise and / or fall time of the pulse electric field is preferably 100 μs or less. 100μ
If it exceeds s, the discharge state easily shifts to an arc and becomes unstable, making it difficult to maintain a high-density plasma state due to a pulsed electric field. Further, the shorter the rise time and the fall time, the more efficiently the gas is ionized during the generation of plasma, but it is actually difficult to realize a pulse electric field with a rise time of less than 40 ns. More preferably, it is 50 ns to 5 μs. Here, the rise time refers to the time during which the voltage change is continuously positive, and the fall time refers to the time during which the voltage change is continuously negative.

It is preferable that the fall time of the pulse electric field is also steep.
It is preferable that the time scale is less than μs. Although it depends on the pulsed electric field generation technology, it is preferable that the rise time and the fall time can be set to the same time.

The electric field intensity of the pulse electric field is 0.5 to 2
It is preferable that the pressure be 50 kV / cm. If the electric field strength is less than 0.5 kV / cm, it takes too much time for the treatment, and if it exceeds 250 kV / cm, arc discharge is likely to occur.

The frequency of the pulse electric field is 0.5 to 10
Preferably, it is 0 kHz. If the frequency is less than 0.5 kHz, the plasma density is low, so that it takes too much time for the treatment,
If it exceeds 100 kHz, arc discharge is likely to occur. More preferably, the frequency is 1 to 100 kHz. By applying such a high-frequency pulsed electric field, the processing speed can be greatly improved.

It is preferable that one pulse duration in the above-mentioned pulse electric field is 1 to 1000 μs. If the time is less than 1 μs, the discharge becomes unstable,
If it exceeds 000 μs, it is easy to shift to arc discharge.
More preferably, it is 3 to 200 μs. Here, one pulse duration is shown in FIG. 1 as an example,
In a pulsed electric field consisting of repetition of ON and OFF,
It refers to the continuous ON time of one pulse.

The processing material of the present invention is a silicon wafer, and the formation of a silicon oxide film by the plasma processing of the present invention is preferably performed at a silicon wafer temperature of 200 to 400 ° C., more preferably at a temperature of 200 to 300 ° C. is there.

The means for bringing the plasma into contact with the silicon wafer include, for example, (1) a method in which a silicon wafer is arranged in a discharge space of plasma generated between opposing electrodes, and the plasma is brought into contact with the silicon wafer; 2) There is a method (remote type) in which plasma generated between opposed electrodes is brought into contact with a silicon wafer disposed outside the discharge space so as to be guided toward the silicon wafer.

As a specific method of the above (1), a method in which a silicon wafer is arranged between parallel plate type electrodes covered with a solid dielectric and brought into contact with plasma, using an upper electrode having a large number of holes. , A method of processing with shower-like plasma, a method of running silicon fever, providing a container-like solid dielectric having an outlet nozzle on one electrode,
For example, a method of spraying plasma from the nozzle onto a silicon wafer disposed on another electrode may be used.

As a specific method of the above (2),
The solid dielectric is extended to form a plasma induction nozzle, such as a method of spraying a silicon wafer placed outside the discharge space, such as a parallel plate electrode, a long nozzle, and a coaxial cylindrical electrode. And a combination of cylindrical nozzles. The material of the nozzle tip is
It is not always necessary to use the above-mentioned solid dielectric, and a metal or the like may be used as long as it is insulated from the above-mentioned electrodes.

Among these methods, the method of spraying plasma generated between the opposed electrodes onto a silicon wafer through a solid dielectric having a gas blowing nozzle is less likely to expose the silicon wafer directly to a high-density plasma space. Since a gas in a plasma state can be carried only to a target portion of the silicon wafer surface to form a silicon oxide film, this is a preferable method in which the electric and thermal load on the silicon wafer is reduced.

In the formation of a silicon oxide film by the plasma treatment of the present invention, a preliminary discharge is preferably performed immediately after the generation of plasma until the discharge is stabilized, and then the substrate is brought into contact with the substrate to be processed, in order to improve the film quality. .

Further, in order to prevent the silicon wafer or the oxide film from coming into contact with the humid air or other impurities in the atmosphere, the treatment can be performed in an inert gas atmosphere. In addition to the device that forms a silicon oxide film by contacting the silicon wafer with the silicon wafer, the vicinity of the contact portion between the plasma and the silicon wafer is in an inert gas atmosphere, particularly, a group consisting of nitrogen, argon, helium, neon, xenon, and dry air An apparatus provided with a mechanism for maintaining at least one kind of gas selected from the following (hereinafter, referred to as “inert gas or the like”) can be used.

In the present invention, as a mechanism for maintaining the vicinity of the contact portion between the plasma and the silicon wafer in an atmosphere of an inert gas or the like, a gas curtain mechanism with an inert gas or the like, a treatment in a vessel filled with an inert gas or the like, or the like. And the like.

As a means for transferring the silicon wafer, a transfer system such as a transfer conveyor or a transfer robot can be used.

As the gas curtain mechanism using the inert gas, a gas exhaust mechanism is provided around the contact portion between the plasma and the silicon wafer, and a gas curtain mechanism using the inert gas is provided around the gas exhaust mechanism. The vicinity of the contact portion with the silicon wafer can be kept in an inert gas atmosphere.

The method and apparatus of the present invention will be described in detail with reference to the drawings. FIG. 2 shows a device that uses a coaxial cylindrical nozzle and maintains the vicinity of a contact portion between plasma and a silicon wafer in an atmosphere of an inert gas or the like by a gas curtain mechanism, and has a gas exhaust mechanism around the contact portion. Further, an example of an apparatus having a device for spraying plasma onto a silicon wafer using a device having a shower function of an inert gas or the like provided with a gas curtain mechanism around the gas exhaust mechanism and a transfer mechanism for the silicon wafer. FIG. In FIG.
1 is a power supply, 2 is an outer electrode, 3 is an inner electrode, 4 is a solid dielectric, 5 is a gas outlet, 6 is a nozzle having a coaxial cylindrical nozzle, 7 is a processing gas inlet, 10 is an inner peripheral exhaust gas. Cylinder, 11 is an outer peripheral exhaust gas cylinder, 12 is an inlet for an inert gas or the like, 13 is a pore for blowing out an inert gas or the like, 14 is a silicon wafer, 41 is a carry-in belt, 42 is a processing unit belt,
Reference numeral 43 denotes a carry-out belt.

For example, the processing gas is introduced into the cylindrical solid dielectric container from the gas inlet 7 in the direction of the white arrow, and the electrode 2 and the cylindrical solid dielectric disposed outside the cylindrical solid dielectric container are processed. By applying a pulsed electric field between the inner electrode 3 disposed inside the body container and the pulsed electric field, the gas is blown out from the outlet 5 as plasma gas, and is mainly sucked and collected from the inner peripheral exhaust gas cylinder 10. On the other hand, the silicon wafer 14 is first carried by the carry-in belt 41,
, And a plasma gas is blown from a gas outlet to form a silicon oxide film. Then, the silicon oxide film is carried out by a carry-out belt 43, and is carried through three carrying steps. Further, the inert gas or the like is introduced from the inlet 12 for the inert gas or the like, and is blown toward the silicon wafer 14 conveyed from the blowout hole 13 for the inert gas or the like at the lower portion, and serves as a gas curtain. Then, the atmosphere of the silicon wafer 14 is maintained at an atmosphere of an inert gas or the like. The inert gas and the like are mainly collected from the outer exhaust gas cylinder 11. Note that the thickness of the formed film can be controlled by using a transport belt whose feed speed can be arbitrarily adjusted. Further, the processing section belt preferably has a heating mechanism.

FIG. 3 shows a device that uses a parallel plate type long nozzle and maintains an atmosphere such as an inert gas in the vicinity of a contact portion between the plasma and the silicon wafer by a gas curtain mechanism. It has an exhaust mechanism, and further includes a device for spraying plasma onto the silicon wafer using a device having a shower function of an inert gas or the like in which a gas curtain mechanism is provided around the gas exhaust mechanism, and a silicon wafer transfer mechanism. It is a figure showing an example of a device provided. 1
Is a power source, 2 is an electrode, 3 is an electrode, 4 is a solid dielectric, 5 is a gas outlet, 7 is a processing gas inlet, 10 is an inner exhaust gas cylinder, 11 is an outer exhaust gas cylinder, and 12 is an inert gas. , 13 denotes a silicon wafer, 14 denotes a silicon wafer, 41 denotes a carry-in belt, 42 denotes a processing unit belt, and 43 denotes a carry-out belt.

In FIG. 3, for example, the processing gas is introduced into the box-shaped solid dielectric container from the gas inlet 7 in the direction of the white arrow, and the electrodes 2 and By applying a pulsed electric field between the inner exhaust gas cylinder 3 and the inner exhaust gas cylinder 10, the plasma gas is blown out from the outlet 5 and is mainly collected by suction. On the other hand, the silicon wafer 14 is first carried by the carry-in belt 41, then carried by the processing unit belt 42, and the plasma gas is blown from the gas outlet to form a silicon oxide film, and then carried out by the carry-out belt 43. 3
It is transported through the transport process of the process. Further, the inert gas or the like is introduced from the inlet 12 for the inert gas or the like, and is blown toward the silicon wafer 14 conveyed from the blowout hole 13 for the inert gas or the like at the lower portion, and serves as a gas curtain. Then, the atmosphere of the silicon wafer 14 is maintained at an atmosphere of an inert gas or the like. The inert gas and the like are mainly collected from the outer exhaust gas cylinder 11. Note that the thickness of the formed film can be controlled by using a transport belt whose feed speed can be arbitrarily adjusted. Further, the processing section belt preferably has a heating mechanism.

It is to be noted that the apparatus having a shower function for the inert gas or the like preferably has a bottom surface as shown in FIGS.

FIG. 4 shows a shower device for an inert gas or the like when a coaxial cylindrical nozzle is used, which corresponds to the bottom surface of the nozzle portion in FIG. The plasma gas is supplied to the gas outlet 5
After forming a silicon oxide film on the silicon wafer, it is mainly discharged from the inner peripheral exhaust gas cylinder 10. Further, the inert gas or the like is blown out from the blowing holes 13 of the inert gas or the like existing in the shower region of the inert gas or the like, and is mainly discharged from the outer exhaust gas cylinder 11.

FIG. 5 shows a shower device for an inert gas or the like when a parallel plate type long nozzle is used, which corresponds to the bottom surface of the nozzle portion in FIG. The plasma gas is blown out from the gas blowout port 5, and after forming a silicon oxide film on the silicon wafer, is mainly discharged from the inner peripheral exhaust gas cylinder 10.
Further, the inert gas or the like is blown out from the blowing holes 13 of the inert gas or the like existing in the shower region of the inert gas or the like, and is mainly discharged from the outer exhaust gas cylinder 11.

In the present invention, as a mechanism for maintaining the vicinity of the contact portion between the plasma and the silicon wafer in an atmosphere of an inert gas or the like, a method of performing the treatment in a container filled with an inert gas or the like is provided. The device shown in FIG.

In the apparatus shown in FIG. 6, a silicon oxide film is formed in a container 30 filled with an inert gas or the like. For example,
A device in which a main portion near the contact portion between the plasma and the silicon wafer is housed in a container 30 such as an inert gas provided with a loading / unloading chamber 31 for using the silicon wafer transfer robot 20 and a shutter 32 therefor is used. Is preferred. In FIG. 6, it is only necessary to always supply the inert gas or the like to the container 30 for the inert gas or the like in the direction of the arrow, there is no need for airtightness, no vacuum pump is required, and a simple blower-type exhaust fan is sufficient. Further, the pressure resistance of the container 30 itself such as an inert gas is not required, and a simple chamber may be used. In a film forming apparatus housed in a container such as an inert gas, XY
The processing gas is introduced into the plasma gas nozzle body 6 having the -Z moving mechanism
4 to form a silicon oxide film. The exhaust gas is exhausted from the exhaust gas cylinder 10. The silicon wafer 14 is loaded and unloaded from the cassette 21 in the loading / unloading chamber 31 by the transfer robot 20. The product after the formation of the silicon oxide film is taken in and out through the shutter 32. Here, as the nozzle body 6, one provided with a container-shaped solid dielectric having an outlet nozzle on one electrode (detailed drawing 2), one provided with a parallel plate type long nozzle (detailed drawing 3), etc. It is.

Further, in the case of using a gun-type plasma generator in which the solid dielectric has a gas outlet nozzle, a preliminary discharge is performed from the start of voltage application to the electrode until the discharge state is stabilized. By using a plasma generation mechanism having a nozzle body standby mechanism for moving the wafer to the wafer surface, generation of defective products is suppressed. FIG. 7 schematically shows the apparatus.

FIG. 7 shows a device in which a processing gas is introduced into the nozzle body 6 and plasma is blown onto the silicon wafer 14. The nozzle body 6 stands by at the position A during the preliminary discharge until the discharge state is stabilized. After the discharge state is stabilized, the silicon wafer 14 is moved to a portion B where the silicon oxide film is to be formed, and the formation of the silicon oxide film is started. Further, in this apparatus, the processing gas can be exhausted by providing the ring-shaped hood 10 surrounding the support table 15, and the transfer robot 20 is provided so that the silicon wafer 14 can be transferred from the wafer cassette 21 to the wafer cassette 21. By taking in and out, a silicon oxide film can be efficiently formed on the silicon wafer. The nozzle body standby mechanism can be used together with an XYZ moving device for sweeping the nozzle body. Further, the apparatus shown in FIG. 7 can be housed in the container 30 filled with the inert gas shown in FIG.

In the atmospheric pressure discharge using the pulsed electric field according to the present invention, the discharge can be directly generated between the electrodes under the atmospheric pressure without depending on the kind of gas at all. Atmospheric pressure plasma device by discharge procedure,
In addition, high-speed processing can be realized at a low temperature by a processing method. Further, parameters related to the formation of the silicon oxide film can be adjusted by parameters such as a pulse frequency, a voltage, and an electrode interval.

The method for producing a silicon oxide film of the present invention can be applied to the production of other semiconductor elements such as an IC circuit, a solar cell, and a switch element of a liquid crystal display.

[0059]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Using an apparatus shown in FIG. 3, a silicon wafer (200 m
mφ), an SiO ₂ film was formed. The parallel plate opposed type long nozzle has a solid dielectric 4 made of alumina sprayed on electrodes 2 and 3 made of aluminum, a slit interval of a plasma outlet is 2 mm, and a distance to a silicon wafer is 6 mm.
And the moving speed of the silicon wafer was 10 mm / min.

As processing gas, 30% of oxygen and 7% of argon
0% of a mixed gas is introduced from the gas inlet 7, and the pulse waveform shown in FIG.
A falling speed of 5 μs and a voltage of 20 kV
Discharge under Pa (atmospheric pressure) to generate plasma, 2
The wafer was processed by spraying on a silicon wafer adjusted to 00 ° C. Nitrogen was used as the inert gas.

On the silicon wafer after the treatment, 50 n
m SiO ₂ films were formed and the process was completed in 20 minutes. Observation of the treated surface by ESCA showed that Si: O = 1: 2 in the entire depth direction up to 50 nm.

Comparative Example 1 Using a thermal oxidation furnace, the same silicon wafer as in Example 1 was heat-treated at 1000 ° C. for 20 minutes to perform surface oxidation. A 20 nm S
An iO ₂ film was formed.

COMPARATIVE EXAMPLE 2 Using a vacuum apparatus, under a 13 Pa environment, a 2.45 GHz frequency was used.
Using electric field conditions, a mixture of 3% oxygen and 97% argon
The same silicon wafer as in Example 1 was heated at 400 ° C.
Treated for 0 minutes. On the processed silicon wafer, 2
3nm SiO ₂A film had been formed.

[0065]

According to the method for forming a silicon oxide film by oxidizing a silicon wafer to which a pulse electric field is applied according to the present invention,
Since the silicon oxide film is formed on the surface of the silicon wafer by bringing the plasma of the processing gas into contact with the silicon wafer at about the atmospheric pressure, the film forming process can be made more efficient at a low temperature and the yield can be improved. It can contribute to improvement. Further, since the method of the present invention can be carried out at a low temperature and under the atmospheric pressure, it can be easily in-lined, and by using the method of the present invention, a reduction in the speed of the entire treatment step can be prevented.

[Brief description of the drawings]

FIG. 1 is a voltage waveform diagram showing an example of a pulse electric field according to the present invention.

FIG. 2 is a diagram showing an example of a silicon oxide film forming apparatus of the present invention.

FIG. 3 is a view showing an example of a silicon oxide film forming apparatus of the present invention.

FIG. 4 is a bottom view of an example of a shower function device such as an inert gas used in the present invention.

FIG. 5 is a bottom view of an example of a shower function device such as an inert gas used in the present invention.

FIG. 6 is a view showing an example of a silicon oxide film forming apparatus of the present invention.

FIG. 7 is a view showing an example of a silicon oxide film forming apparatus of the present invention.

[Explanation of symbols]

 Reference Signs List 1 power supply (high-voltage pulse power supply) 2, 3 electrode 4 solid dielectric 5 gas outlet 6 nozzle body 7 gas inlet 10, 11 exhaust gas cylinder 12 inlet for inert gas, etc. 13 outlet for inert gas, etc. Reference Signs List 14 silicon wafer 15 support base 20 transfer robot 21 cassette 22 arm 30 container 31 carry-in / out room 32 shutter 41 carry-in belt 42 processing unit belt 43 carry-out belt

Claims (8)

[Claims] At least one opposing surface of a pair of opposing electrodes is provided with a solid dielectric under a pressure near the atmospheric pressure,
A method in which plasma obtained by introducing an oxygen-containing gas between the pair of opposed electrodes and applying a pulsed electric field is brought into contact with a silicon wafer to form a silicon oxide film on the surface of the silicon wafer. 2. The method for forming a silicon oxide film according to claim 1, wherein the oxygen-containing gas contains oxygen gas at 4% by volume or more. 3. The silicon oxide according to claim 1, wherein the pulse-shaped electric field has a pulse rise and / or fall time of 100 μs or less and an electric field intensity of 0.5 to 250 kV / cm. A method of forming a film. 4. A pulse-like electric field having a frequency of 0.5 to 1
The method for forming a silicon oxide film according to any one of claims 1 to 3, wherein the frequency is 00 kHz and the pulse duration is 1 to 1000 µs. 5. A pair of opposing electrodes having a solid dielectric on at least one opposing surface, a mechanism for introducing a processing gas between the pair of opposing electrodes, and a mechanism for applying a pulsed electric field between the electrodes. An apparatus for forming a silicon oxide film on a surface of a silicon wafer, comprising a mechanism for bringing plasma obtained by the pulse electric field into contact with the silicon wafer. 6. A mechanism for bringing plasma into contact with a silicon wafer, wherein the plasma generated between the opposing electrodes is guided toward the silicon wafer through a solid dielectric having a gas outlet nozzle. Item 6. An apparatus for forming a silicon oxide film according to Item 5. 7. A mechanism for bringing plasma into contact with a silicon wafer, wherein the plasma generated between the opposed electrodes is guided toward the silicon wafer through a solid dielectric having a gas outlet nozzle after preliminary discharge. The apparatus for forming a silicon oxide film according to claim 5. 8. An apparatus for forming a silicon oxide film, comprising: the apparatus according to claim 5; and a silicon wafer transport mechanism.