JPH10229080A - Processing method of oxide, deposition method of amorphous oxide film and amorphous tantalun oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a processing method of oxide suitable for high volume production in which insulation of an oxide can be enhanced greatly without causing surface roughening or compositional shift due to cross contamination or sputtering effect during processing by performing heat treatment at a specified temperature in an atmosphere containing ozone. SOLUTION: A nitride layer 12 is formed on the surface of a low resistance n<+> type Si substrate 11 and Ta2 O6 film 13 is deposited thereon. The n<+> type Si substrate 11 deposited with Ta2 O6 film 13 is then placed on a heater in an ozone annealing chamber and subjected to quick heat treatment at anneal temperature thus performing ozone annealing in an atmosphere containing ozone gas under the atmospheric pressure. In this regard, the ozone concentration of ozone anneal atmosphere is 5-20vol.% in O3 /O2 ratio, the anneal temperature is 300-500 deg.C and the anneal time is 5-60min. Thereafter, an Al electrode 14 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of treating an oxide, a method of forming an amorphous oxide film, and an amorphous tantalum oxide film. For example, the present invention relates to a method of forming an oxide film used as a dielectric film of a capacitor in a semiconductor device. It is suitable for application to improvement of film quality.

[0002]

2. Description of the Related Art In ultra-highly integrated semiconductor devices, insulation properties such as an oxide film used as a dielectric film of a capacitor and an interlayer insulating film for forming fine wiring are one of the bottlenecks in practical use of the device. It has become. In particular, in the case of a high dielectric oxide film necessary for obtaining a high-capacity capacitor, a relatively thick film having a thickness of about 100 nm has been conventionally formed, but an ultra-thin film having a thickness of about 10 nm has recently been formed. In the era when it is necessary to improve the insulating property, it has become a very important issue.

Conventional techniques for improving the insulating property of an oxide film are roughly classified into the following two methods. In either case, oxygen deficiency (defect due to oxygen deficiency) in the film is eliminated by introducing oxygen into the oxide film.

The first method is a method in which oxygen is introduced during the formation of an oxide film, in which activated oxygen is supplied into the oxide film while forming the oxide film.

A second method is to perform annealing in an oxygen atmosphere after forming an oxide film. In this method, annealing is further performed in an oxygen plasma atmosphere so that activated oxygen generated by oxygen plasma is removed from the oxide film. The method can be divided into a method of supplying into the inside and a method of performing high-temperature annealing in a dry oxygen atmosphere.

[0006]

However, in the first method, it is extremely difficult to uniformly supply activated oxygen into the oxide film. Particularly, when the oxide film is formed on a large-sized substrate suitable for mass production. Not suitable for

In the second method of performing annealing in an oxygen plasma atmosphere, the oxygen plasma is generated in a vacuum, so that the concentration of activated oxygen generated by the oxygen plasma is considerably low. The effect of improvement is small. Further, there is a problem that the surface of the oxide film is roughened due to the sputtering effect of the oxide film due to the oxygen plasma, and cross contamination from the inner wall of the chamber is caused by the oxygen plasma. In the second method of performing high-temperature annealing in a dry oxygen atmosphere, since oxygen gas is not activated, a high-temperature thermal diffusion process is required to supply oxygen into the oxide film. is necessary. This high-temperature process tends to cause a problem such as a composition shift of the oxide film due to the diffusion of the constituent elements of the oxide film and the constituent elements of the substrate (particularly, the Si substrate) in the semiconductor process.

Therefore, an object of the present invention is to provide an oxide which can greatly improve the insulating properties of an oxide, is suitable for mass production, and does not cause surface roughness or composition deviation due to cross contamination or sputtering effect during processing. An object of the present invention is to provide a method of processing an object.

Another object of the present invention is to form an amorphous oxide film having a high dielectric property and a high insulating property and a uniform film quality, and suitable for mass production. An object of the present invention is to provide a method for forming an amorphous oxide film which does not cause surface roughness or composition deviation due to the effect.

Still another object of the present invention is to provide an amorphous tantalum oxide film having a high dielectric property and a high insulating property and having a uniform film quality over the entire film.

[0011]

In order to achieve the above object, a method for treating an oxide according to the first invention of the present invention is to perform a heat treatment at a temperature of 300 to 500 ° C. in an atmosphere containing ozone. It is characterized by having made it.

In the first invention, the lower limit of the heat treatment temperature is set to 300 ° C. If the heat treatment temperature is lower than 300 ° C., the diffusion of oxygen in the oxide becomes insufficient and the insulating property due to the reduction of oxygen defects is reduced. The reason for the lowering of the heat treatment temperature is set to 500 ° C. because the effect of the improvement is reduced, which is not preferable. If the heat treatment temperature is higher than 500 ° C., the life of ozone is shortened, and the insulating property is improved by reducing oxygen defects. In particular, when the oxide to be treated is amorphous, crystallization (micro-crystallization) proceeds to generate a grain boundary serving as a leak current path, and the effect of improving the insulating property is reduced. It is because it is not preferable.

In the first aspect of the present invention, from the viewpoint of enhancing the effect of improving the insulating property of the oxide, preferably, 35
Heat treatment is performed at a temperature of 0 to 450 ° C.

In the first aspect, the concentration of ozone in the atmosphere for the heat treatment is preferably 5 to 20% by volume of ozone to oxygen. Here, the lower limit of the volume ratio is set to 5% in order to sufficiently obtain the effect of improving the insulating properties of the oxide, and the upper limit of 20% is set to reduce the safety when using ozone. This is to ensure.

In the first invention, the heat treatment is typically performed under atmospheric pressure, but may be performed under reduced pressure if necessary.

In the first invention, although it depends on the heat treatment temperature and the concentration of ozone in the atmosphere, in order to sufficiently improve the insulating properties of the oxide film by the heat treatment,
Heat treatment is performed for 5 to 60 minutes.

In the first invention, the heat treatment is typically performed by rapid thermal annealing (RTA).
The heat treatment is performed by a method, but depending on the case, a heat treatment (furnace anneal) using a normal heat treatment furnace may be performed, or a heat treatment by laser light irradiation may be performed.

In the first invention, in order to prolong the life of ozone and to maintain the concentration of ozone at a constant value, heat treatment is preferably performed in a processing chamber in which at least the inner wall is cooled. The cooling of the processing chamber may be performed by any method such as water cooling, air cooling, and cooling using various refrigerants.

The first invention is basically applicable to any oxide treatment regardless of whether it is a high dielectric substance or a low dielectric substance. As specific examples of the oxides which are subject to the above, tantalum pentoxide (Ta ₂ O ₅ ) and a composition formula Ta ₂ O _x having a composition close thereto, where 4.5 ≦ x ≦
5.5) amorphous or crystalline tantalum oxide, Pb (Zr, Ti) O ₃ (PZT), (Pb,
La) (Zr, Ti) O ₃ (PLZT), SrTiO ₃
(STO), (Ba, Sr) TiO ₃ (BST), Ba
An amorphous or crystalline oxide having a composition corresponding to an oxide having a perovskite crystal structure, such as TiO ₃ (BTO), PbTiO ₃ , CeO ₂ , Zr
An amorphous or crystalline oxide having a composition corresponding to an oxide having a fluorite-type crystal structure such as O ₂ or Y-stabilized ZrO ₂ is given. Further, the oxide to be processed is a low dielectric material, which is formed by thermal oxidation.
iO ₂ and, like SiO ₂ and the like which are deposited by chemical vapor deposition using ozone and tetraethoxysilane as a reaction gas (CVD) method. Note that an amorphous oxide refers to an oxide containing fine clusters of up to several Å.

A method of forming an amorphous oxide film according to a second aspect of the present invention is to perform a heat treatment of the amorphous oxide film at a temperature of 300 to 500 ° C. in an atmosphere containing ozone after forming the amorphous oxide film. It is characterized by having done.

In the second invention, the formation of the amorphous oxide film is typically performed at a temperature of 500 ° C. or less. The amorphous oxide film is formed by a physical vapor deposition (PVD) method such as a sputtering method in addition to a chemical vapor deposition (CVD) method. The latter PVD
In the case of using the method, it is generally desirable to form a film at normal temperature.

In the second aspect, matters relating to the heat treatment in an atmosphere containing ozone are the same as those in the first aspect. Further, the oxide constituting the amorphous oxide film is the same as in the first invention.

The amorphous tantalum oxide film according to the third aspect of the present invention has a compositional formula of Ta ₂ O _x (4.5
.Ltoreq.x.ltoreq.5.5), having a relative dielectric constant of 20 or more and a leakage current density of 5 × 10 ⁻⁸ A when an electric field of 1.5 × 10 ⁶ V / cm is applied. / Cm ²
It is characterized by the following.

In the third invention, _x in Ta ₂ O x is typically 4.5 ≦ x ≦ 5.0.

The amorphous tantalum oxide film according to the third invention can be easily formed by using the method for forming an amorphous oxide film according to the second invention.

According to the first aspect of the present invention, since the heat treatment is performed at a temperature of 300 to 500 ° C. in an atmosphere containing ozone, activated oxygen can be uniformly dispersed in the oxide. To fill the oxygen vacancies, thereby greatly improving the insulating properties of the oxide film. In this case, activated oxygen can be uniformly supplied to an oxide film formed over a large substrate, which is suitable for mass production. Furthermore, since plasma is not used, there is no problem of surface contamination due to cross contamination or sputtering effect from the inner wall of the chamber. In addition, since the heat treatment temperature is as low as 500 ° C. or less, no oxide composition deviation occurs.

Here, why ozone contained in the atmosphere of the heat treatment is effective for improving the insulating property of the oxide will be described.

Ozone is usually generated by decomposing oxygen gas by silent discharge as follows.

3O ₂ → 2O ₃ (−68.2 cal / mol) (1) This ozone is activated by a thermal energy near the oxide surface, as shown by the following formula, with a strong oxidizing power. It is decomposed into reduction of oxygen O and (3p) and oxygen (O _2).

O ₃ → O (3p) + O ₂ (2) The activated oxygen O (3p) thus generated combines with the oxygen vacancies on the surface of the oxide and in the oxide to remove the oxygen vacancies. fill in. Thereby, the main cause of the current leakage is eliminated, and the insulating property of the oxide is improved.

According to the second aspect of the present invention, after the amorphous oxide film is formed, the amorphous oxide film is heat-treated at a temperature of 300 to 500 ° C. in an atmosphere containing ozone. Therefore, uniform film quality can be obtained over the entire film by being amorphous, and high dielectric properties and high insulation properties can be obtained despite being amorphous.

According to the third aspect of the present invention, the relative dielectric constant is not less than 20 and 1.5 × 10 ⁶ V / cm.
Leakage current density when applying an electric field of 5 × 10 ⁻⁸ A
/ Cm ² or less, it has high dielectric properties and high insulation properties, and because it is amorphous, uniform film quality can be obtained over the entire film.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

First, an ozone annealing apparatus used in the following embodiments will be described. FIG. 1 shows the configuration of the ozone annealing apparatus.

As shown in FIG. 1, in this ozone annealing apparatus, an ozone generator 3 is connected to a chamber 2 made of quartz, for example, in which a substrate 1 to be subjected to ozone annealing is placed. The ozone is allowed to flow into the chamber 2. The chamber 2 is made of, for example, an 8-inch diameter substrate 1.
It is designed to be able to handle. In the chamber 2, a substrate 1 to be annealed is placed on a heater (not shown). The substrate 1 can be heated by the RTA method. Further, a cooling pipe 4 is attached to the chamber 2, and the inner wall of the chamber 2 and the vicinity of the flow path of the ozone gas can be cooled by always flowing, for example, water through the cooling pipe 4. ,
The life of ozone is extended, and the ozone concentration can be maintained at a desired value.

Next, a first embodiment of the present invention will be described. In the first embodiment, as shown in FIG. 2, first, the surface of a low-resistance n ⁺ -type Si substrate 11 is washed with dilute hydrofluoric acid to remove a natural oxide film and the like, and then the surface is removed. Nitriding layer (hereinafter referred to as “RTN layer”) by nitriding by RTN (rapid thermal nitridation) method 12
To form The nitridation by the RTN method is performed, for example, at 850 ° C. in an ammonia (NH ₃ ) gas atmosphere.
Perform for seconds. The thickness of the RTN layer 12 is, for example, 2 nm. Next, on this RTN layer 12, for example, low pressure CVD (L
A Ta ₂ O ₅ film 13 is formed by a PCVD method. An example of conditions for forming the Ta ₂ O ₅ film 13 by the LPCVD method is pentaethoxy tantalum (Ta (OC ₂
Using H _{5) 5)} organic liquid raw material, using a helium gas as a carrier gas, the pressure during film formation is 0.5Tor
r, the film forming temperature is 400 to 480 ° C., for example, 450 ° C., the film thickness is 10 to 50 nm, for example, 35 nm, and the film forming speed is about 10 nm / min. In addition, Ta (OC ₂
H ₅₎ supply amount of ₅ to 0.05～0.10Sccm. When the crystal state of the Ta ₂ O ₅ film 13 thus formed was examined by electron beam diffraction (restricted field diffraction), a halo pattern was obtained.
The a ₂ O ₅ film 13 was found to be amorphous.
Further, when the Ta ₂ O ₅ film 13 was examined by thin-film X-ray diffraction, no diffraction pattern was observed. From this, it was verified that the Ta ₂ O ₅ film 13 was amorphous. Is done.

The RTN layer 1 is formed on the n ⁺ type Si substrate 11.
The formation of the Ta ₂ O ₅ film 13 after the formation of
^{When the} Ta ₂ O ₅ film 13 is directly formed on the ⁺ type Si substrate 11, an SiO ₂ film (not shown) is formed on the surface of the n ⁺ type Si substrate 11 and an oxide film with the Ta ₂ O ₅ film 13 is formed. This is to prevent the dielectric constant of the whole from lowering, thereby preventing this.

Next, the n ⁺ -type Si substrate 1 on which the Ta ₂ O ₅ film 13 is formed is placed on a heater in the chamber 2 of the ozone annealing apparatus shown in FIG. 1 and heated to an annealing temperature by the RTA method. Then, annealing (hereinafter referred to as "ozone annealing") is performed in an atmosphere containing ozone gas at atmospheric pressure. Here, the ozone concentration in the atmosphere of the ozone annealing is 5 to 20% by volume in an O ₃ / O ₂ ratio, the annealing temperature is 300 to 500 ° C., and the annealing time is 5 to 60 minutes. The crystalline state of the Ta ₂ O ₅ film 13 after the ozone annealing was examined by electron diffraction, since the halo pattern is obtained, the the Ta ₂ O ₅ film 13
It was confirmed that after the ozone annealing, the amorphous state was maintained.

After that, the Ta ₂ O ₅ film 13
Al is selectively formed by a vacuum deposition method using a metal mask (a so-called metal mask) having holes of 0 to 800 μm.
The Al electrode 14 is formed by forming a film.

As described above, the lower electrode composed of the n ⁺ -type Si substrate 11, the Ta ₂ O ₅ film 13 formed thereon via the RTN layer 12, and the upper electrode composed of the Al electrode 14 thereon A capacitor having a MIS structure is formed.

In order to confirm the effect of improving the insulating property of the Ta ₂ O ₅ film 13 by the ozone annealing in the first embodiment, the O ₃ / O ₂ concentration value in the atmosphere was set to 6 to 7% by volume. Ozone annealing samples were manufactured by changing the annealing temperature from 400 ° C. to 450 ° C. and the annealing time from 15 minutes to 60 minutes, and their electrical characteristics were examined. The electrical characteristics were examined by measuring current-voltage characteristics, capacitance-voltage characteristics, and capacitance-frequency characteristics.

FIG. 3 shows a leak current density (J) -electric field strength curve obtained by current-voltage measurement. Ta ₂ O ₅
The thickness of the film 13 is 35 nm. In FIG. 3, a is Ta ₂ O
₅ is a sample subjected to ozone annealing at 450 ° C. for 30 minutes under atmospheric pressure after the film 13 is formed, and b is a Ta ₂ O ₅ film 13
Is a sample subjected to ozone annealing at 400 ° C. for 30 minutes under atmospheric pressure after film formation, c is a sample subjected to ozone annealing at 400 ° C. for 60 minutes under atmospheric pressure after film formation of the Ta ₂ O ₅ film 13, and d is a sample This is a measurement result of a sample in which ozone annealing is not performed after the Ta ₂ O ₅ film 13 is formed.

As can be seen from FIG. 3, the Ta ₂ O ₅ film 13 not subjected to ozone annealing after film formation (FIG.
Poole-Fr has a very weak insulation property in which a leak current of 10 ^-4 A / cm ² or more flows at an electric field strength of MV / cm.
It will be destroyed while showing the behavior of enkel. On the other hand, when ozone annealing is performed at a temperature of 400 to 450 ° C. for 30 to 60 minutes under the atmospheric pressure after the Ta ₂ O ₅ film 13 is formed, the electric field intensity of 1 MV / cm is 10 ⁻⁸ A. / Cm ² , and a remarkable improvement in insulation was observed. These results
Even at a low temperature of 400 to 450 ° C, T
It is considered that oxygen defects in the a ₂ O ₅ film 13 could be effectively reduced and the concentration of impurities such as carbon was also reduced. As described above, this mechanism is considered to be due to the fact that activated oxygen O (3p) generated by the thermal decomposition of ozone gas during ozone annealing reacts with oxygen vacancies in the Ta ₂ O ₅ film 13.

FIG. 4 shows the electrical polarity of the sample which was subjected to ozone annealing at 450 ° C. for 30 minutes under atmospheric pressure after the Ta ₂ O ₅ film 13 was formed. In FIG. 4, Al (+) is Al
When the electrode 14 is a positive electrode, Al (−) is the Al electrode 14
Shows the case where is a negative electrode. As can be seen from FIG.
In the entire electric field intensity range applied between the electrode 14 and the n ⁺ -type Si substrate 11, the leak current density of Al (−) was measured to be smaller than that of Al (+). A leakage current density of × 10 ⁻⁹ A / cm ² was obtained. The presence of this polarity in the MIS structure is due to the Al electrode 1
It is considered that this is caused by depletion of the surface of the n ⁺ -type Si substrate 11 when a negative bias voltage is applied to No. 4.

FIG. 5 shows Ta Ta before and after ozone annealing.
Current ₂ O ₅ film 13 - obtained by measuring the voltage characteristic,
The change of the leak current density (J) and the resistivity (ρ) when the applied electric field strength is 1 MV / cm is shown. Ozone annealing was performed at 400 ° C. for 30 minutes under atmospheric pressure. As can be seen from FIG. 5, the ozone annealing can reduce the leak current density by three digits or more compared to the leak current density of the Ta ₂ O ₅ film 13 not subjected to the ozone annealing. FIG. 5 shows that when the thickness of the Ta ₂ O ₅ film 13 is 20 nm and 35 nm, respectively, the leak current densities after ozone annealing are 5.4 × 10 ⁻⁸ A / cm ² and 1.5 × 10 ^−. It turns out that it shows ⁸ A / cm ² . FIG. 5 shows, for comparison, a Si ₃ N ₄ film and an ON film (SiO 2 film).
₂ film and the Si ₃ N values of the measured leakage current density and resistivity for a conventional capacitor using a double-layer film) and ₄ film as a dielectric film is also shown. On the other hand, the Ta ₂ O ₅ film 1
Since 6.7 × 10 ¹³ Ω · cm was obtained as the maximum resistivity of No. 3 and good insulating properties were exhibited, ozone annealing was effective for improving the insulating property of the Ta ₂ O ₅ film 13. It can be seen that it is.

FIG. 6 shows the leakage current density before and after annealing of the Ta ₂ O ₅ film 13 and the electric field at a leakage current density of 5 × 10 ⁻⁸ A / cm ² by varying the annealing conditions after the film formation. The result of having measured the change of intensity | strength is shown. The thickness of the Ta ₂ O ₅ film 13 is 10 nm. FIG.
In the figure, A is a sample not subjected to annealing after the Ta ₂ O ₅ film 13 is formed, and B is 30 ° C. at 700 ° C. in a dry oxygen atmosphere.
C is a sample annealed at 700 ° C. for 30 minutes in a dry oxygen atmosphere and then ozone annealed at 400 ° C. for 15 minutes under atmospheric pressure, and D is a sample obtained by annealing at a frequency of 13.56 MHz. .5kW R
40 F under 2.5 Torr pressure using F power
A sample subjected to oxygen plasma annealing at 0 ° C. for 14 minutes, E
Shows the measurement results of a sample which was subjected to ozone annealing at 400 ° C. for 15 minutes under atmospheric pressure. As can be seen from FIG. 6, 30 ° C. at 700 ° C. in a dry oxygen atmosphere.
Minutes in annealed samples was performed (B in FIG. 6), Ta ₂ O
₅ film 13 sample does not perform annealing after deposition to a leakage current density from 10 ^-2 A / cm ² units leakage current density measured at the sample of 10 ^-7 A / cm ² units (A in Figure 6) T
Although the leakage characteristics of the a ₂ O ₅ film 13 are improved, it is considered that this level of leakage current is still too high to be used as a dielectric film of a capacitor in a bipolar IC, a DRAM or the like. As already reported, although high-temperature annealing can remove impurities such as oxygen defects and carbon in the film, the grain boundary in the film becomes a leak current path due to the progress of crystallization. It is thought that it is. On the other hand, in the sample subjected to oxygen plasma annealing at 400 ° C. for 14 minutes (D in FIG. 6), a remarkable improvement in the leak characteristic was observed in the low electric field strength region of 1 MV / cm.
Approximately 10 ^-6 A / cm in an electric field intensity region of 2 MV / cm or more
^The leakage current density is as high as about ² . On the other hand, in the sample (E in FIG. 6) subjected to ozone annealing at 400 ° C. for 15 minutes under atmospheric pressure, the leak current density was 5 × 10 ⁻⁸ A / cm ² or less even at an electric field intensity of 2 MV / cm. You can see that it is.

Here, it is considered that the fundamental difference in the effect of improving the insulating property between the oxygen plasma annealing method and the ozone annealing method as described above is caused by the pressure during the process. That is, since this ozone annealing is performed under atmospheric pressure, it is considered that activated oxygen having a higher density can react with the Ta ₂ O ₅ film 13 than in the case of oxygen plasma annealing performed in vacuum. The effectiveness of this ozone annealing is as follows. Immediately after annealing at 700 ° C. for 30 minutes in a dry oxygen atmosphere,
It can also be confirmed from the result of performing ozone annealing at 00 ° C. for 15 minutes (C in FIG. 6). In this case, than if only performed for 30 minutes annealing at 700 ° C. in a dry oxygen atmosphere, given the fact that sufficient leakage current density is reduced, Ta ₂ O ₅ with ozone annealing
It is considered that the oxygen vacancies in the grains including a part of the grain boundaries of the film 13 are filled to some extent.

FIG. 7 shows Ta ₂ O subjected to ozone annealing.
₅ shows a change in capacitance value per unit area and a change in equivalent SiO ₂ effective film thickness (t _eff (SiO ₂ )) depending on the film thickness of the film 13. The capacitance value per unit area measured with a Ta ₂ O ₅ film 13 having a thickness of 20 nm is 7.8 fF / μm ² , which is conventionally used as a dielectric film of a capacitor when the film thickness is the same. This is about three times the capacitance per unit area of the Si ₃ N ₄ film. In addition, a T film having a thickness of 20 nm
For a ₂ O ₅ film 13, 4.3 nm of t _eff (Si
O ₂ ) is obtained. In the case of the Ta ₂ O ₅ film 13 having a thickness of 10 nm, a 3.2 nm t _eff (Si
O ₂ ) can be obtained, and the RTN layer 12 can be thinned or the underlying n ⁺ -type Si substrate 1 serving as a storage node can be obtained.
By roughening the surface shape of 1 and increasing the surface area,
It is believed that even thinner t _eff (SiO ₂ ) can be achieved.

Another important property when applying the Ta ₂ O ₅ film 13 as a dielectric film of a capacitor of a bipolar IC is the stability of the capacitance value depending on the frequency. 8 and 9 show the frequency characteristics of the capacitance of the Si ₃ N ₄ film and the Ta ₂ O ₅ film 13 used as the dielectric film of the conventional capacitor. Here, from 40MHz to 2GH
In the frequency range up to z, an Au electrode was used instead of the Al electrode 14 in order to reduce the contact resistance between the probe and the electrode. 8 and 9, in the frequency range of 10 kHz to 2 GHz, the Si ₃ N ₄ film and the Ta ₂ O ₅ film 13 are formed.
In both cases, the capacitance value shows stability within 5%. Also,
At the same film thickness, the capacitance value of the Ta ₂ O ₅ film 13 in the high frequency region is about three times the capacitance value of the Si ₃ N ₄ film.

As described above, according to the first embodiment, after the amorphous Ta ₂ O ₅ film 13 is formed on the n ⁺ -type Si substrate 11 via the RTN layer 12, Since the ozone annealing is performed at a temperature of 300 to 500 ° C., the relative dielectric constant is 20 or more and 1.5 M
The leakage current density when applying an electric field of V / cm is 5 ×
An amorphous Ta ₂ O ₅ film 13 having a high dielectric property and a high insulating property of 10 ⁻⁸ A / cm ² or less can be obtained. Here, the relative dielectric constant of the Ta ₂ O ₅ film 13 is 2
A high value of 8.5 has already been obtained. In addition, even when a large n ⁺ -type Si substrate 11 is used, activated oxygen can be uniformly supplied to the Ta ₂ O ₅ film 13 by this ozone annealing, which is suitable for mass production. Further, since plasma is not used for the treatment of the Ta ₂ O ₅ film 13, there is no problem of surface contamination due to cross contamination or sputtering effect from the inner wall of the chamber as in the related art. Moreover, the temperature of the ozone annealing is 300 to 50.
Since the temperature is as low as 0 ° C., the ozone annealing does not cause a composition deviation of the Ta ₂ O ₅ film 13.

Further, according to the first embodiment, the following advantages can be obtained in addition to the above advantages. That is, assuming that the Ta ₂ O ₅ film 13 is polycrystalline, when an electric field is applied to the Ta ₂ O ₅ film 13, an electric field concentration occurs at the grain boundaries, and as a result, the insulating property is greatly reduced. May be reduced. In addition, Ta ₂ O ₅ film 1
If 3 is polycrystalline, it is generally difficult to obtain a uniform film quality over the entire film, and thus, for example, in a DRAM or the like, there arises a problem that the capacitance value of a capacitor varies between memory cells. On the other hand, in the first embodiment, since the Ta ₂ O ₅ film 13 is amorphous, there is no such problem. That is, since the amorphous Ta ₂ O ₅ film 13 is used, there is no problem of electric field concentration and the insulating property can be maintained. In addition, since uniform film quality can be obtained over the entire film, variation in the capacitance value of the capacitor between the memory cells can be suppressed, and a uniform capacitance can be obtained.

As described above, a capacitor having an MIS structure having good characteristics and high reliability can be realized.

FIG. 10 shows a second embodiment of the present invention. In the second embodiment, the present invention
Ta ₂ O used as a dielectric film of an AM capacitor
A case where the present invention is applied to a process for improving the insulating properties of _five films will be described.

As shown in FIG. 10, in the second embodiment, after an interlayer insulating film 22 is formed on a p-type Si substrate 21 on which elements have been formed in advance, the p-type Si substrate 2
The contact hole 24 is formed by etching away the portion of the interlayer insulating film 22 above the n ⁺ -type drain region 23 of the n-channel MOSFET serving as an access transistor formed in 1. Next, this contact hole 2
A polycrystalline Si plug 25 is formed in the substrate 4, and a metal silicide film 26 such as a TiSi ₂ film is formed on the surface of the polycrystalline Si plug 25 in a self-aligned manner. Next, after a cylindrical polycrystalline Si film 27 is formed, Ta ₂ O _{5 is} formed on the surface of the cylindrical polycrystalline Si film 27.
A film 28 is formed. Thereafter, similarly to the first embodiment, ozone annealing of the Ta ₂ O ₅ film 28 is performed at a temperature of 300 to 500 ° C. under atmospheric pressure. Here, the ozone annealing of the Ta ₂ O ₅ film 28 is performed at a temperature of 500 ° C. or less, so that the metal silicide film 26 can be prevented from being deteriorated.

According to the second embodiment, in a DRAM, Ta ₂ used as a dielectric film of a capacitor is used.
The dielectric and insulating properties of the O ₅ film 28 can be greatly improved. In addition, since the Ta ₂ O ₅ film 28 and the subsequent ozone annealing are performed at a low temperature of 500 ° C. or less, the drain region 23 and other diffusion layers formed in the p-type Si substrate 21 are removed. Without adverse effects such as re-diffusion of impurities.
For example, so-called SALICIDE (self-aligned silic
ide) When the technology is used for a gate wiring or the like, it is most promising as a capacitor forming technology in an embedded high-density memory.

FIG. 11 shows a third embodiment of the present invention. In the third embodiment, the invention is applied to a Ta IC used as a dielectric film of a capacitor of a bipolar IC.
A case where the present invention is applied to a process for improving the insulating property of a ₂ O ₅ film will be described.

As shown in FIG. 11, in the third embodiment, a p ⁺ -type isolation region 32 is formed in a p-type Si substrate 31 to perform element isolation. An n ^- type Si epitaxial layer 33 is grown thereon. Next, the n ^- type Si epitaxial layer 33
Is selectively thermally oxidized to form a field insulating film 34 made of a SiO ₂ film, and then an n-type impurity is ion-implanted into the n ⁻ -type Si epitaxial layer 33 in a portion surrounded by the field insulating film 34 or The n ⁺ -type layer 35 is formed by the diffusion method. Next, after an SiO ₂ film 36 is formed on the n ⁻ -type Si epitaxial layer 33, openings 37 and 38 are formed by removing predetermined portions of the SiO ₂ film 36 by etching. Next, on the n ⁺ -type layer 35 at the portion of the opening 38, the same R as in the first embodiment is formed.
A Ta ₂ O ₅ film 39 is formed via a TN layer (not shown). Thereafter, in the same manner as in the first embodiment, the Ta
The ozone annealing of the ₂ O ₅ film 39 is performed at atmospheric pressure for 3 hours.
It is performed at a temperature of 00 to 500 ° C. Next, an Al electrode 41 is formed via a polycrystalline Si film 40 in which an impurity is doped in the opening 37, and an Al electrode 42 is formed on the Ta ₂ O ₅ film 39 formed in the opening 38. I do.

According to the third embodiment, in the bipolar IC, the dielectric and insulating properties of the Ta ₂ O ₅ film 39 used as the dielectric film of the capacitor can be greatly improved.

Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, as shown in FIG. 2, first, the surface of a low-resistance n ⁺ -type Si substrate 11 is washed with dilute hydrofluoric acid or the like to remove a natural oxide film or the like, and then the surface is removed. The RTN layer 12 is formed by nitriding by the RTN method. The reason for forming the RTN layer 12 is as described in the first embodiment. The nitridation by the RTN method is performed, for example, at 850 ° C. in an NH ₃ gas atmosphere.
For 60 seconds. The thickness of the RTN layer 12 is, for example, 2n
m. Next, on this RTN layer 12, for example, LPCV
The Ta ₂ O ₅ film 13 is formed by the method D. This LPCV
As an example of the conditions for forming the Ta ₂ O ₅ film 13 by the method D, an organic liquid raw material of Ta (OC ₂ H ₅ ) ₅ is used, a nitrogen gas is used as a carrier gas, and the pressure during the film formation is 0.5 Torr, a film forming temperature of 400 to 500 ° C., a film thickness of 8 to 50 nm, and a film forming rate of about 10 nm / min.
The supply amount of Ta (OC ₂ H ₅ ) ₅ is 0.05 to 0.5.
It is 10 sccm. The Ta ₂ film thus formed
When the crystal state of the O ₅ film 13 was examined by electron beam diffraction (restricted field diffraction), a halo pattern was obtained, indicating that the Ta ₂ O ₅ film 13 was amorphous. Further, when the Ta ₂ O ₅ film 13 was examined by thin film X-ray diffraction, no diffraction pattern was observed, so that it is verified that the Ta ₂ O ₅ film 13 is amorphous.

Next, the n ⁺ -type Si substrate 11 on which the Ta ₂ O ₅ film 13 is formed is placed on a heater in the chamber 2 of the ozone annealing apparatus shown in FIG. 1 and heated to an annealing temperature by the RTA method. Ozone annealing is performed at atmospheric pressure. Here, the ozone concentration in the atmosphere of the ozone annealing is 5 to 20% by volume in an O ₃ / O ₂ ratio, the annealing temperature is 300 to 500 ° C., and the annealing time is 5 to 60 minutes. Ta ₂ O ₅ film 13 after ozone annealing
The halo pattern was obtained by examining the crystal state of the film by electron beam diffraction (restricted field diffraction). From this, the Ta ₂ O ₅ film 13 maintained an amorphous state even after ozone annealing. It was confirmed that.
On the other hand, for comparison, the crystal state of the Ta ₂ O ₅ film 13 was determined by thin-film X-ray diffraction for a sample obtained by forming the Ta ₂ O ₅ film 13 and then performing annealing at 700 ° C. for 30 minutes in a dry oxygen atmosphere. Upon examination, the result shown in FIG. 12 was obtained. As shown in FIG. 12, the Ta ₂ O ₅ film 13 has a δ-Ta ₂ O ₅ type crystal structure, and has (100), (0)
It can be seen that polycrystals are oriented in the (01) and (101) directions.

After that, a film having a diameter of 20 is formed on the Ta ₂ O ₅ film 13.
Al is selectively formed by a vacuum deposition method using a metal mask (a so-called metal mask) having holes of 0 to 800 μm.
The Al electrode 14 is formed by forming a film.

As described above, the lower electrode composed of the n ⁺ -type Si substrate 11, the Ta ₂ O ₅ film 13 formed thereon via the RTN layer 12, and the upper electrode composed of the Al electrode 14 thereon A capacitor having a MIS structure is formed.

FIG. 13 shows the results of measuring the change in the leak current density at various applied electric field strengths before and after annealing of the Ta ₂ O ₅ film 13 by variously changing the conditions of the annealing performed after the film formation. The thickness of the Ta ₂ O ₅ film 13 is 10 nm. In FIG. 3, A is a sample not subjected to annealing after the Ta ₂ O ₅ film 13 is formed, and B is 70% in a dry oxygen atmosphere.
C shows the measurement result of the sample annealed at 0 ° C. for 30 minutes, and C shows the measurement result of the sample annealed at 400 ° C. under the atmospheric pressure for 15 minutes. As can be seen from FIG.
In a sample (B in FIG. 13) annealed at 700 ° C. for 30 minutes in a dry oxygen atmosphere, the Ta ₂ O ₅ film 13
From the leakage current density of 10 ⁻² A / cm ^{2 to} the leakage current density of 10 ⁻⁷ A / cm ^2, which was measured for the sample (A in FIG. 13) where annealing was not performed after the film formation of Ta ₂ O. _Five
Although the leakage characteristics of the film 13 are improved, it is considered that this level of leakage current is still too high to be used as a dielectric film of a capacitor in a bipolar IC, a DRAM, or the like. As already reported, although high-temperature annealing can remove impurities such as oxygen defects and carbon in the film, the grain boundary in the film becomes a leak current path due to the progress of crystallization. It is thought that it is. In contrast, the sample (C in FIG. 13) subjected to ozone annealing at 400 ° C. for 15 minutes under atmospheric pressure has a relatively high
It can be seen that the leak current density is as low as 5 × 10 ⁻⁸ A / cm ² or less even at an electric field strength of MV / cm. From this result, it can be seen that the ozone annealing can sufficiently remove oxygen vacancies and impurities such as carbon and hydrogen in the Ta ₂ O ₅ film 13. Also, this Ta ₂ O ₅ film 13
It remains amorphous even after ozone annealing,
It is considered that the electric field concentration at the grain boundary which occurs in the sample of FIG. 13B does not occur. From these facts, it is understood that by forming the amorphous Ta ₂ O ₅ film 13 at a low temperature and then performing ozone annealing at a low temperature, it is possible to obtain a sufficiently high insulating property while maintaining the amorphous state.

According to the fourth embodiment, the same advantages as in the first embodiment can be obtained.

Next, a fifth embodiment of the present invention will be described. In this fifth embodiment, as shown in FIG. 14, first, after removing the like natural oxide film was washed by such dilute hydrofluoric acid a surface of a low-resistance n ⁺ -type Si substrate 51, the n ⁺ A Ti film 52 having a thickness of, for example, 10 nm and a TiN film 53 having a thickness of, for example, 50 nm are sequentially formed on the mold Si substrate 51 by, for example, a sputtering method. Next, a Ru film 54 having a thickness of, for example, 10 to 30 nm is formed on the TiN film 53 by, for example, a sputtering method. Next, a Ta ₂ O ₅ film 55 is formed on the Ru film 54 by, for example, the LPCVD method. An example of conditions for forming the Ta ₂ O ₅ film 55 by the LPCVD method is as follows.
a (OC ₂ H ₅ ) ₅ organic liquid raw material, a nitrogen gas as a carrier gas, and a pressure of 0.5 To during the film formation.
rr, film formation temperature 400 to 500 ° C., film thickness 8 to 50 n
m, and the deposition rate is about 10 nm / min. When the crystal state of the Ta ₂ O ₅ film 55 thus formed was examined by electron beam diffraction (restricted field diffraction), a halo pattern was obtained. From this, the Ta ₂ O ₅ film 55 was amorphous. I understand. Moreover, the the Ta ₂ O ₅ film 55 was examined by thin film X-ray diffraction, since it was not observed whatsoever of the diffraction pattern, the Ta ₂ O
₅ It is verified that the film 55 is amorphous.

Next, the n ⁺ -type Si substrate 51 on which the Ta ₂ O ₅ film 55 is formed is placed on a heater in the chamber 2 of the ozone annealing apparatus shown in FIG. 1 and heated to an annealing temperature by the RTA method. Ozone annealing is performed at atmospheric pressure. Here, the ozone concentration in the atmosphere of the ozone annealing is 5 to 20% by volume in an O ₃ / O ₂ ratio, the annealing temperature is 300 to 500 ° C., and the annealing time is 5 to 60 minutes. The Ta ₂ O ₅ film 55 after performing the ozone annealing
The halo pattern was obtained by examining the crystal state of this by electron beam diffraction (restricted field diffraction).
It was confirmed that the ₂ O ₅ film 55 maintained the amorphous state even after the ozone annealing.

After that, the Ta ₂ O ₅ film 55
Al is selectively formed by a vacuum deposition method using a metal mask (a so-called metal mask) having holes of 0 to 800 μm.
The Al electrode 56 is formed by forming a film.

As described above, a capacitor having an MIM structure including the lower electrode composed of the Ru film 54, the Ta ₂ O ₅ film 55 formed thereon, and the upper electrode composed of the Al electrode 56 thereon is formed. .

FIG. 15 is obtained by current-voltage measurement.
4 shows a leakage current density-electric field strength curve. Ta_TwoO_FiveMembrane 5
The film thickness of No. 5 is 10 nm. In FIG. 15, a is Ta_TwoO_Five
After the film 55 is formed, the film is heated at 400 ° C. for 5 minutes under atmospheric pressure.
Sample subjected to zon annealing, b is Ta_TwoO_FiveFormation of membrane 55
After film deposition, ozone annealing at 450 ° C for 5 minutes under atmospheric pressure
Sample, c is Ta_TwoO_FiveAfter the film 55 is formed,
5 shows the measurement results for a sample not subjected to annealing.
As can be seen from FIG._TwoO_FiveAfter the formation of the film 55,
Ozone ani for 5 minutes at 400-450 ° C under atmospheric pressure
In the samples (a and b in FIG. 15) subjected to the
Extremely low density and noticeable improvement in leak characteristics
Especially at 450 ° C for 5 minutes under atmospheric pressure.
In the sample subjected to the annealing (FIG. 15B), 1.5M
About 3 × 10 at V / cm electric field strength ^-8A / cm^TwoLess than
High leakage current density.

FIG. 16 shows that at 450 ° C. under atmospheric pressure
7 shows the capacitance of the Ta ₂ O ₅ film 55 subjected to ozone annealing for one minute and the frequency characteristics of t _eff (SiO ₂ ) obtained from the capacitance measurement. From FIG. 16, it can be seen that a high capacitance value and a thin t _eff (SiO ₂ ) are obtained in the frequency range of 10 kHz to 4 MHz, even though the Ta ₂ O ₅ film 55 is amorphous. The thinnest t _eff (SiO ₂ ) obtained in this case is 1.2 nm, which can be used as a dielectric film of a capacitor in a gigabit class ultra-highly integrated semiconductor memory.

FIG. 17 shows a sixth embodiment of the present invention. In the sixth embodiment, the present invention
A case where the present invention is applied to a process for improving the insulating property of a Ta ₂ O ₅ film used as a dielectric film of a capacitor having a simple stack structure in AM will be described.

As shown in FIG. 17, in the sixth embodiment, after an interlayer insulating film 62 is formed on a p-type Si
The contact hole 64 is formed by etching away the portion of the interlayer insulating film 62 above the n ⁺ -type drain region 63 of the n-channel MOSFET serving as an access transistor formed in 1. Next, this contact hole 6
4, a polycrystalline Si plug 65 is formed. Next, a Ti film 66 and a TiN film 6 are formed on the entire surface by, for example, a sputtering method.
After the film 7 and the Ru film 68 are sequentially formed, the Ru film 68, the TiN film 67, and the Ti film 66 are patterned by etching such that a portion on the polycrystalline Si plug 65 is left. Next, a Ta ₂ O ₅ film 69 is formed on the entire surface by, eg, LPCVD. Thereafter, similarly to the first or fifth embodiment, ozone annealing of the Ta ₂ O ₅ film 69 is performed at a temperature of 300 to 500 ° C. under atmospheric pressure. Further, a TiN film 70 is formed on the entire surface by, for example, a sputtering method.

According to the sixth embodiment, in a DRAM, Ta ₂ used as a dielectric film of a capacitor is used.
The dielectric and insulating properties of the O ₅ film 69 can be greatly improved. Further, since the Ta ₂ O ₅ film 69 and the subsequent ozone annealing are both performed at a low temperature of 500 ° C. or less, the same advantages as those described in the second embodiment can be obtained.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical concept of the present invention are possible.

For example, in the above-described first embodiment, the case where the capacitor is formed on the n ⁺ type Si substrate 11 has been described. However, the substrate on which the capacitor is formed is another semiconductor substrate such as a GaAs substrate. Or a glass substrate on which a transparent electrode is formed. The same applies to the fourth and fifth embodiments.

The configuration of the ozone annealing apparatus shown in FIG. 1 is merely an example, and another configuration may be used if necessary. Further, for example, the chamber 2 may be made of, for example, stainless steel as needed.

[0077]

As described above, according to the method for treating an oxide according to the present invention, the heat treatment of the oxide is performed at a temperature of 300 to 500 ° C. in an atmosphere containing ozone. It can greatly improve the insulating properties of the object, and is suitable for mass production, and does not cause surface roughness or composition deviation due to cross contamination or sputtering effect during processing.

According to the method for forming an amorphous oxide film of the present invention, after the amorphous oxide film is formed, the amorphous oxide film is heat-treated at a temperature of 300 to 500 ° C. in an atmosphere containing ozone. This makes it possible to form an amorphous oxide film with high dielectric and high insulation properties and uniform film quality, and is suitable for mass production, and surface roughness and composition deviation due to cross contamination and sputtering effect during processing. Does not occur.

Further, according to the amorphous tantalum oxide film of the present invention, high dielectric properties and high insulating properties can be obtained, and the film quality can be made uniform over the entire film.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an ozone annealing apparatus used in a first embodiment of the present invention.

FIG. 2 shows Ta ₂ O _{5 according to} the first embodiment of the present invention.
It is sectional drawing which shows the capacitor formed for the insulation measurement of a film.

FIG. 3 is a schematic diagram for explaining an effect of improving a leak characteristic of a Ta ₂ O ₅ film by ozone annealing according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram for explaining the polarity of leakage current density-electric field strength characteristics measured for the capacitor according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a result of measuring a change in a leak current density and a resistivity of a Ta ₂ O ₅ film by ozone annealing according to the first embodiment of the present invention.

FIG. 6 shows Ta ₂ O _{5 according to} the first embodiment of the present invention.
The conditions of the annealing performed after the film formation were changed variously, and the leakage current density and the leakage current density at each applied electric field were 5%.
FIG. 9 is a schematic diagram illustrating a result of measuring a change in an electric field at × 10 ⁻⁸ A / cm ² .

[7] Ta ₂ capacitance values and SiO ₂ effective equivalent thickness per unit area of the first Ta ₂ O ₅ film subjected to an ozone annealing in embodiment and the Si ₃ N ₄ film of the present invention
FIG. 4 is a schematic diagram illustrating a change depending on the thickness of an O ₅ film.

FIG. 8 shows the results of the ozone annealing of the Ta ₂ O ₅ film and the Si ₃ N ₄ film according to the first embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating capacitance-frequency characteristics in a frequency range from kHz to 4 MHz.

FIG. 9 shows a graph of 40% of the Ta ₂ O ₅ film and the Si ₃ N ₄ film subjected to the ozone annealing according to the first embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating capacitance-frequency characteristics in a frequency range from MHz to 2 GHz.

FIG. 10 is a cross-sectional view for explaining a second embodiment of the present invention.

FIG. 11 is a cross-sectional view for explaining a third embodiment of the present invention.

FIG. 12 shows a temperature of 700 ° C. in a dry oxygen atmosphere.
FIG. 9 is a schematic diagram showing the result of thin-film X-ray diffraction measurement of a Ta ₂ O ₅ film that has been annealed for one minute.

FIG. 13 shows a fourth embodiment of the present invention in which Ta ₂ O is used.
FIG. 9 is a schematic diagram showing the results of measuring the change in leak current density at each applied electric field while changing the conditions of annealing performed after the formation of _five films.

FIG. 14 shows a fifth embodiment of the present invention in which Ta ₂ O is used.
FIG. 9 is a cross-sectional view showing a capacitor formed for measuring the insulation properties of _five films.

FIG. 15 is a schematic diagram for explaining an effect of improving a leak characteristic of a Ta ₂ O ₅ film by ozone annealing in a fifth embodiment of the present invention.

FIG. 16 is a diagram illustrating a Ta ₂ O ₅ film subjected to ozone annealing according to a fifth embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating capacitance-frequency characteristics in a frequency region up to z.

FIG. 17 is a cross-sectional view for explaining a sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Chamber, 3 ... Ozone generator, 11, 51 ... n ⁺ type Si substrate, 12 ... R
TN layer, 13, 28, 39, 55, 69 ... Ta ₂ O
₅ films, 14, 56 ... Al electrode

Claims (22)

[Claims] 1. The method according to claim 1, further comprising:
A method for treating an oxide, wherein the heat treatment is performed at a temperature of 500 ° C. 2. The method for treating an oxide according to claim 1, wherein said heat treatment is performed at a temperature of 350 to 450 ° C. 3. The method according to claim 1, wherein the concentration of ozone in the atmosphere is 5 to 20% by volume of ozone to oxygen. 4. The method according to claim 1, wherein said heat treatment is performed under atmospheric pressure. 5. The method according to claim 1, wherein said heat treatment is performed for 5 to 60 minutes. 6. The method according to claim 1, wherein said heat treatment is performed by a rapid heat treatment method. 7. The oxide treatment method according to claim 1, wherein the heat treatment is performed in a treatment chamber where at least the inner wall is cooled. 8. The method according to claim 1, wherein the oxide is tantalum oxide. 9. The method according to claim 1, wherein the oxide has a composition corresponding to an oxide having a perovskite crystal structure. 10. The method according to claim 1, wherein the oxide has a composition corresponding to an oxide having a fluorite-type crystal structure. 11. A method for forming an amorphous oxide film, wherein after forming the amorphous oxide film, the amorphous oxide film is heat-treated at a temperature of 300 to 500 ° C. in an atmosphere containing ozone. 12. The method for forming an amorphous oxide film according to claim 11, wherein said amorphous oxide film is formed at a temperature of 500 ° C. or lower. 13. The method for forming an amorphous oxide film according to claim 11, wherein said heat treatment is performed at a temperature of 350 to 450 ° C. 14. The method according to claim 11, wherein the concentration of ozone in the atmosphere is 5 to 20% by volume of ozone to oxygen. 15. The method for forming an amorphous oxide film according to claim 11, wherein said heat treatment is performed under atmospheric pressure. 16. The method for forming an amorphous oxide film according to claim 11, wherein said heat treatment is performed for 5 to 60 minutes. 17. The method for forming an amorphous oxide film according to claim 11, wherein said heat treatment is performed by a rapid heat treatment method. 18. The method for forming an amorphous oxide film according to claim 11, wherein the heat treatment is performed in a processing chamber in which at least the inner wall is cooled. 19. The method according to claim 11, wherein the amorphous oxide film is an amorphous tantalum oxide film. 20. The method according to claim 11, wherein the amorphous oxide film has a composition corresponding to an oxide having a perovskite crystal structure. 21. The method according to claim 11, wherein the amorphous oxide film has a composition corresponding to an oxide having a fluorite crystal structure. 22. A composition formula of Ta ₂ O _x (where 4.5 ≦
x ≦ 5.5), having a relative dielectric constant of 20 or more and a leakage current density of 5 × 10 ⁻⁸ A / when an electric field of 1.5 × 10 ⁶ V / cm is applied. amorphous tantalum oxide film which is characterized in that cm ² or less.