JP2668459B2 - Insulation film manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides a method for producing a silicon oxide film having excellent interface characteristics with a semiconductor interface.

[0002]

2. Description of the Related Art In general, as an oxide insulating film, a gate insulating film of an insulated gate field effect transistor and a base insulating film formed on a glass substrate when a semiconductor device is formed on the glass substrate are known. . As the manufacturing method, a thermal oxidation method, a photo CVD method, and a sputtering method are known.

A typical example of the thermal oxidation method is to react oxygen and silane at a temperature of 400 to 500 ° C. or higher to form a silicon oxide film on a substrate. When a gate insulating film of a transistor (hereinafter referred to as a TFT) is to be formed by this thermal oxidation method, one conductivity type semiconductor (for example, an N-type semiconductor or a P-type semiconductor) is given by heat energy at this time. (For example, boron and phosphorus) diffuse into unnecessary portions such as a genuine semiconductor, or cause unnecessary heat damage.

[0004] However, the thermal oxidation method is frequently used in spite of the above-mentioned problems because a good interface state density of about 2 × 10 ¹⁰ eV ^-1 cm ^-2 can be obtained.

[0005] Further, since the photo-CVD method has no effect of heat at all, it has the advantage that it can solve the problem of the thermal oxidation method and can realize an interface state comparable to the thermal oxidation method. . However, there is a drawback that the film forming rate is very slow, and there is a problem that productivity is low.
Further, ultraviolet light sources typified by UV light lamps used in a photo-CVD apparatus have a short life and are expensive, and thus have a cost problem.

[0006] In the sputtering method, a film can be formed at a low temperature of 150 ° C. or lower, and the film forming speed is high, and a uniform film can be formed over a large area. Integrated circuits such as LSI, for example, DRA
The film can be formed simply by preparing a target of tantalum oxide, titanium oxide, barium titanate, lead titanate, or the like used for a capacitor or the like in an M (dynamic memory) cell. Etc.

In particular, the silicon oxide film obtained by sputtering using a silicon target in an atmosphere of 100% oxygen has a 7 × 10 film comparable to the thermal oxidation method.
^It has a low interface state density of about ¹⁰ eV ^-1 cm ^-2 , and since the ions of argon atoms, which are unwanted substances in the silicon oxide film, do not exist in the film, there is a fixed charge. It is possible to obtain a stable insulating film. However, the silicon oxide film obtained by sputtering in an atmosphere of 100% oxygen does not become a practical insulating film unless hydrogenated by hydrogen thermal annealing.

[0008]

The silicon oxide film obtained by sputtering is not practical unless hydrogen thermal annealing is performed. An object of the present invention is to obtain optimum conditions for the hydrogen thermal annealing.

[0009]

According to the present invention, there is provided a method of forming an oxide insulating film on a substrate by sputtering in an atmosphere of 100% oxygen, and forming the oxide insulating film in a hydrogen atmosphere of 250 ° C. to 350 ° C. And hydrogen thermal annealing.

The substrate in the present invention is a substrate such as a glass substrate, a semiconductor layer, or a metal, and the purpose is to electrically insulate or electrically protect the upper surface, side surfaces, or periphery thereof or to utilize an electronic phenomenon in an insulating film. In which an oxide insulating film is formed. The electronic phenomenon in the insulating film is, for example, an electronic phenomenon in the interface between the insulating film (insulator) and the semiconductor, and application examples thereof include an insulating gate type field effect transistor (TFT), MIM type element, MIS type element and the like. . Other materials that use an oxide insulating film include a capacitor in a semiconductor integrated circuit and a silicon oxide film formed as a base film on a glass substrate on which a semiconductor device is formed.

The sputtering according to the structure of the present invention comprises:
It is preferable to use a magnetron type RF sputter device which is widely used when forming an insulating film.
Other sputtering methods may be used. The reason why sputtering is performed in an atmosphere of 100% oxygen is to obtain a dense electrically stable insulating film in which impurities are not mixed. Further, thermal annealing at a temperature of 250 to 350 ° C. in a 100% hydrogen atmosphere is performed in this temperature range in order to obtain a good interface state of about 7 × 10 ¹⁰ eV ⁻¹ cm ^−2.
It is based on the result of an experiment conducted by the present inventor that it is optimal to perform thermal annealing for 60 minutes. Hereinafter, examples will be shown, and the configuration of the present invention will be described in detail.

[0012]

【Example】

[Example 1] In this example, a silicon oxide film was formed on a silicon substrate in an atmosphere of 100% oxygen, and hydrogen thermal annealing was performed for 30 minutes at a temperature of 350 degrees in a hydrogen atmosphere. It was done.

In this embodiment, a silicon oxide film was formed as a sample on a silicon substrate by using a magnetron type RF sputtering apparatus. The conditions for producing this sample were as follows: RF output 4
The process was performed at 00 W, a deposition pressure of 0.5 pa, an atmosphere of 100% oxygen, and a substrate temperature of 150 ° C. In addition, an ingot of polycrystalline silicon was used as a target.

The substrate temperature at the time of this sputtering can be around room temperature. In addition, light energy, electromagnetic energy,
Alternatively, the activation or oxygenation of the oxygen atmosphere by using the ECR condition is more effective (to increase the degree of ionization) to form a dense oxide insulating film (a silicon oxide film in this embodiment). is there.

FIGS. 1 to 3 are graphs showing the relationship between the oxygen partial pressure ratio in the film formation atmosphere and various characteristics of the silicon oxide film during sputtering of the silicon oxide film manufactured in this embodiment.
In this embodiment, oxygen (O ₂ ) and argon (Ar)
The sputtering was performed in an atmosphere mixed with the above, and the oxygen partial pressure was changed by changing the mixture ratio of oxygen and argon. The oxygen partial pressure is defined by ((oxygen partial pressure / (oxygen partial pressure + argon partial pressure)). Therefore, an oxygen partial pressure ratio of 1.0 means an atmosphere of 100% oxygen. In this example, the parameters other than the oxygen partial pressure during film formation were all set under the same conditions.

FIG. 1 is a graph showing the relationship between the oxygen partial pressure ratio of the atmosphere during film formation and the interface state density at the interface between the sample silicon substrate and the silicon oxide film. The measurement of the interface state density was performed using the sample and the measurement method described in Example 2.

FIG. 2 shows the relationship between the oxygen partial pressure ratio of the atmosphere during film formation and the flat band voltage V _FB . In order to examine the characteristics shown in FIG. 2, a silicon oxide film (thickness: 1000 mm) was formed on a silicon semiconductor (thickness: 200 μm) as a sample.
Was formed by sputtering, further the silicon oxide film for 30 minutes hydrogen thermal annealing at a temperature of 350 ° C. in a hydrogen atmosphere, it was used to form the aluminum electrode 1 _mm phi on the silicon oxide film.

In this embodiment, hydrogen thermal annealing is performed using a diffusion furnace, but an LPCVD apparatus, a thermal CVD apparatus, or the like may be used. In general, annealing is performed in a state where the substrate is set up to increase the processing capacity. However, when a large-area glass substrate is used as the substrate, it is preferable to level the glass substrate to make the influence of gravity uniform.

From FIG. 1, it is understood that the interface state density is lower as the oxygen partial pressure during film formation is higher. In this case, since the conditions other than the oxygen partial pressure during film formation are the same, it can be considered that the interface state density depends on the oxygen partial pressure during film formation.

The flat band voltage V _FB is a voltage required to cancel the influence of fixed charges in the insulating film, and the lower the value, the higher the characteristic of the insulating film.

As is clear from FIG. 2, the flat band voltage decreases as the proportion of oxygen (oxygen partial pressure) in the atmosphere during sputtering increases. That is, FIG. 2 shows that a silicon oxide film obtained by sputtering in an atmosphere having a high oxygen content has excellent characteristics as an insulating film. Also, the proportion of oxygen should be as high as possible.
It is also clear from FIGS. 1 and 2 that the sputtering is preferably performed in a% atmosphere.

FIG. 3 shows the relationship between the oxygen partial pressure and the withstand voltage during film formation. In this case, the withstand voltage means that the above-mentioned leak current to the 1 _mm φ aluminum electrode is 1
The voltage when the current exceeded μA was used. Since the measured values vary greatly depending on the sample, they indicate X (center black point) and σ (dispersion sigma value) (upper and lower limits). As is clear from FIG. 3, the larger the oxygen ratio (oxygen partial pressure) in the atmosphere during sputtering, the higher the withstand voltage and the smaller the variation due to the sample. The large variation among the samples in the measurement of the breakdown voltage indicates that the stability as the insulating film is poor. In addition, in mass production, it is needless to say that it is not industrially preferable that the characteristics vary.

It can be seen from FIG. 3 that the silicon oxide film formed by sputtering in an atmosphere of 100% oxygen is the most electrically stable insulating film.

As shown in FIGS. 1, 2, and 3, when the proportion of argon in the atmosphere during film formation is high, the characteristics of the formed silicon oxide film as an insulating film deteriorate. The reason for this is that atoms of argon, which are unnecessary impurities in the silicon oxide film, act as fixed charges in the silicon oxide film. In addition, damage to the surface of the silicon oxide film due to argon ions during sputtering also causes variations in these characteristics.

Although silicon oxide is used as an example of an oxide insulating film in this embodiment, tantalum oxide, titanium oxide, barium titanate, or titanic acid used as a capacitor in a semiconductor integrated circuit can be used as the oxide insulating film. A metal oxide insulating film of lead or the like can be formed with the structure of the present invention. Specifically, a film is formed by sputtering using a target of the metal oxide or metal in an atmosphere of 100% oxygen, and further hydrogen thermal annealing is performed in a hydrogen atmosphere of 250 ° C. to 350 ° C. to form an insulating film. Is formed.

Furthermore, when the structure of the present invention is applied to form a film of an oxide such as an oxide semiconductor, an oxide insulator, or an oxide superconductor by a sputtering method, it is still possible to form a dense oxide. Absent. In this case, another appropriate annealing method may be used instead of the hydrogen thermal annealing.

As described above, in Example 1, the effect and basis of setting the atmosphere to 100% oxygen during film formation have been described through the evaluation of the silicon oxide film formed by sputtering as an insulating film. In 2, the effect and grounds of hydrogen thermal annealing of a film after film formation in a hydrogen atmosphere at 250 ° C. to 350 ° C. will be described.

[Embodiment 2] In this embodiment, hydrogen thermal annealing after sputtering, which is a constitution of the present invention, will be described based on experimental results. FIG. 4 shows a well-known MIS as a sample of an insulating film evaluation method used for a semiconductor device.
The configuration of the mold is shown. The configuration shown in FIG. 4 is a polycrystalline silicon wafer 41 having a thickness of 200 μm, a 100% oxygen atmosphere according to the present invention, a substrate temperature of 150 ° C.
A silicon oxide film (SiO ₂ ) film 4 is formed by a magnetron type RF sputtering device using a polycrystalline silicon target as a target under the film forming conditions of RF output of 400 W and film forming pressure of 0.5 Pa.
2 is formed, the formed silicon oxide film is subjected to hydrogen thermal annealing for 30 minutes, and aluminum electrodes 43 and 44 are further provided. The annealing time was 30 minutes, and hydrogen was introduced at 1 liter / minute at atmospheric pressure.

FIG. 5 shows a well-known Ramp Voltag.
6 shows CV characteristics at a low frequency obtained by adding e. As a method of measuring CV characteristics, an aluminum electrode 4
3 and 44 by applying a voltage.

Each curve of the CV characteristic of FIG. 5 corresponds to the difference in temperature during the hydrogen thermal annealing. As shown in FIG. 5, each curve showing the CV characteristic is given the temperature at the time of hydrogen thermal annealing or its presence or absence. Parameters other than the hydrogen heat annealing time are common to the samples showing each CV characteristic.

As shown in FIG. 5, the best CV characteristics were obtained when the hydrogen thermal annealing temperature was 350 degrees.
The method of evaluating the CV characteristics will be described later as [Supplementary Explanation].

The steepness of the C-V characteristic obtained by this measurement method, when used as a gate oxide film of the insulated gate field effect transistor shown in FIG. 6, a silicon oxide film used for this measurement I _D - as it is reflected in the V _G characteristics. Therefore, when the insulated gate field effect transistor shown in FIG. 6 is manufactured by using the silicon oxide film having the CV characteristic as the gate oxide film at the annealing temperature of 450 degrees, which seems to have a good steepness of the curve, Part of the curve shown in FIG. 4 appears as it is in the I _D -V _G characteristic of the insulated gate field effect transistor, which causes unstable operation.

In addition, C- at the annealing temperature of 450 ° C.
The interface state density at the interface between the insulating film and the semiconductor of the sample exhibiting V characteristics is higher than when the hydrogen thermal annealing temperature is 350 degrees. It is considered that this is because, for some reason, a new level, which is a cause of disturbance of a part of the curve shown in FIG. 4, is generated in the forbidden band of the semiconductor in the vicinity of the interface. One of the causes is considered to be a difference in thermal expansion coefficient between silicon and silicon oxide.

FIG. 6 shows an N-channel insulated gate field effect transistor (NTFT) as an example of an insulated gate field effect transistor (TFT). In FIG. 6, 61 is a glass substrate, 62 is a base silicon oxide film, 63 is a source region, 64 is a channel region, 65 is a drain region,
66 is a gate insulating film, 67 is a source electrode, 68 is a gate electrode, 69 is a drain electrode, and 601 is an interlayer insulator.
FIG. 6 shows an NTFT, but a PTFT may also be used. Needless to say, the TFT is not limited to the format shown in FIG.

As can be seen from FIG. 5, the CV characteristics of the silicon oxide film which is not annealed after the film formation is nearly flat,
Even if this silicon oxide film is used as a gate oxide film,
_D -V _G characteristics, i.e. it is not possible to obtain an insulating gate field effect transistor having a I _D -V _G characteristics having a steepness.

FIG. 5 shows that the CV characteristics are improved by gradually increasing the annealing temperature.

In addition, the following

[Table 1] Table 1 summarizes the relationship between the interface state density at the interface between the silicon oxide film 42, which is the insulating film of each sample, and the polycrystalline silicon 41, and the temperature during hydrogen thermal annealing.

[0038]

[Table 1]

As shown in Table 1, the annealing temperature was 350
Temperature, the interface state density is about 7 × 10 ¹⁰ eV ⁻¹ cm ⁻² , but when the annealing temperature is 300 ° C., 1 × 10 ¹¹ eV
^-1 cm ^-2 , 3 × 10 ¹¹ when the annealing temperature is 250 degrees
eV ^-1 cm ^-2 , and 1 × 10 ¹² eV ^-1 cm ^-2 when not annealed.

The measurement of the interface state is performed by a well-known High Low Frequency
The ency was measured using the CV method. This method is based on a comparison between CV characteristics when a high-frequency signal is applied and CV characteristics when a low-frequency signal is applied.
And S, in this case, the insulating film 42 and the polycrystalline semiconductor layer 41
This is a method for calculating the value of the interface state density of the interface with the interface.

Comparing the interface state densities of the samples shown in Table 1, the interface state density was lowest when the hydrogen thermal annealing temperature was 350 ° C. A silicon oxide film at a temperature of 350 degrees is optimal.

As a practical interface state density at the interface between the gate oxide film and the channel formation region of a general TFT, 1
If a value of 0 ¹¹ eV ^-1 cm ^-2 is to be obtained, as in the configuration of the present invention, hydrogen thermal annealing is performed in a 100% hydrogen atmosphere at a temperature of 250 to 350 degrees and an annealing time of 30 to 6 degrees.
From Table 1, it can be concluded that it is better to perform the treatment in 0 minutes.

Regarding the annealing time, there was no significant difference in the effect even if the annealing time was 30 minutes or more. However, if the effect of hydrogen thermal annealing can be obtained without variation, it is preferable to take 30 to 60 minutes.

In this embodiment, if the atmosphere at the time of annealing is a gas other than hydrogen, for example, nitrogen, no effect can be obtained at all. The cause of the interface state density is as follows.
It is considered that there are bond defects due to the structure / composition of the transition layer at the interface, that is, due to dangling bonds, point defects at the semiconductor surface, and bond lengths and bond angles of bonds near the interface. (References Applied Physics Handbook P423 Mar. 30, 1990 Published by Maruzen Co., Ltd.)

On the other hand, a method using hydrogen plasma is known as a method for neutralizing dangling bonds of an amorphous semiconductor. As described above, if the generation of interface states is due to dangling bonds, point defects, or disorder of dangling bonds at the interface, it is considered that neutralization of dangling bonds due to hydrogenation has a great effect. Can be

In the structure of the present invention, hydrogen is used for annealing for the above reason, and it is clear that inert gas has no effect. However, the hydrogen thermal annealing in the configuration of the present invention may be performed in an atmosphere of a mixed gas of an inert gas and hydrogen for some reasons.

In this example, oxygen 1 was used as a means for producing a silicon oxide film having good characteristics as a gate oxide film of an insulating gate type field effect transistor (TFT).
Sputtering is performed in a 00% atmosphere, and the silicon oxide film after the film formation is completed by hydrogen thermal annealing in a 100% hydrogen atmosphere. Hydrogen thermal annealing is indispensable.

The fact that the insulating film has good characteristics as the gate oxide film of the insulating gate type field effect transistor guarantees that the insulating film has good characteristics as an insulating film used in all electronic devices. .

In general, basic requirements for an insulating film provided on a semiconductor surface are as follows: (1) The interface state density is small, and the fixed charge density at the interface can be controlled. (2) The film is dense and adheres well to protect the semiconductor from the outside. (3) The interface stress is small. (4) It is thermally and chemically stable and has long-term reliability. (5) Good compatibility between the passivation film (insulating film) forming process and other processes for device fabrication. (6) Good step coverage. (End of Applied Physics Handbook P422 Published March 30, 1990 by Maruzen Co., Ltd.)

As described in Example 2, the interface state density of (1) can be achieved by changing the annealing temperature of the thermal hydrogen annealing. Examples of the fixed charge at the interface include sodium ions and alkali ions. As a method for neutralizing these fixed charges, fluorine is typically used as a target when sputtering is performed in an atmosphere of 100% oxygen. 0.1 to 5% by weight of a halogen element or phosphorus and boron in a concentration of 1 × 10 ^{19 to} 5 × 10 ²⁰ cm ⁻³ . Further, these elements may be added to the atmosphere. As described above, it is also possible in the configuration of the present invention to control the fixed charge density at the interface.

(2) and (4) are one of the features of the present invention that a dense oxide insulating film containing no impurities is obtained by sputtering in an atmosphere of 100% oxygen. In the case of (3), considering the characteristic of the present invention that the film formation by the sputtering method is performed at a low temperature of 150 ° C. or lower, the argon atoms as impurities are not mixed into the film, and the damage due to the sputtering is not considered. It is obvious that the configuration has the effect of course.
The advantages (5) and (6) are naturally obtained in the configuration of the present invention in view of the well-known feature of the sputtering method that film formation by the sputtering method can be stably performed over a large area.

[Supplementary Explanation] Hereinafter, as a supplementary explanation, the relationship between the shape of the curve of the CV characteristic in FIG. 5 and the existence of interface states will be described. FIG. 7 shows an equivalent circuit of the sample having the MIS structure shown in FIG. 4, and the graph of FIG. 5 will be described with reference to FIG. Hereinafter, FIG. 7 which is an equivalent circuit of FIG. 4 will be described. In FIG. 4, the silicon oxide film sandwiched between the aluminum electrodes 43 and 44 and the polycrystalline silicon semiconductor film 41 form a capacitor (capacitance C), which is a capacitor C _OX and C of the silicon oxide film itself. It is shown as a series combination of the capacitance of the depletion region of the semiconductor indicated by _D. The capacity C _D of the depletion region of the semiconductor is shown as a variable capacitor in FIG. 7 so changed by the voltage applied to the electrodes. Also, C _i is the capacitance caused by the interface state.

Hereinafter, the C-V characteristic in the case where the ideal interface characteristic, that is, the interface state in FIG. 4 is sufficiently small, that is, in the condition where C _i can be ignored in FIG. 7, will be described. In this case, a measurement signal voltage of sufficiently low frequency is applied along with the DC bias so that the electrons can follow the signal voltage.
(Reference: July 15, 1981, 3rd edition, published by Corona Co., Ltd. Semiconductor Device Physics (2) P64) The voltage in this specification and in FIG. 5 indicates a voltage of a DC bias applied together with an AC signal. is there.

If the interface characteristic between the polycrystalline silicon semiconductor 41 and the silicon oxide film 42 in the MIS structure shown in FIG. 4 is good, the interface level is considered to be negligible, so that C _i can be ignored. . Therefore, the capacitor C
Is the following formula

(Equation 1) Is shown.

[0055]

(Equation 1)

Further, the standard value (C / C) which is the unit of the vertical axis in FIG.
C _OX ) is as follows

(Equation 2) Is shown.

[0057]

(Equation 2)

Considering now that a negative voltage is applied to the aluminum electrode 43 of FIG. 3, holes accumulate at the boundary between the polycrystalline silicon semiconductor film 41 and the silicon oxide film 42.
Capacitance C _D of the polycrystalline silicon semiconductor film 41 increases.
as a result,

## EQU2 ## As is _clearer , C / C _OX approaches 1.

When the voltage applied to the aluminum electrode 43 is sufficiently small, the capacitance C _D of the polycrystalline silicon semiconductor film 41 is depleted near the interface between the polycrystalline silicon semiconductor film 41 and the silicon oxide film. Only the capacity of the area is reduced. As a result the above formula

The value of C / C _OX shown in _Equation 2 is smaller than 1.

[0060] Further, when a positive voltage is applied to the aluminum electrode 43, the electrons are accumulated polycrystalline silicon semiconductor film 41 in the boundary portion of the silicon oxide film 42, the capacitance C _D of the polycrystalline silicon semiconductor film 41 is negative Is increased in the same manner as when the voltage is applied to the aluminum electrode 43. Therefore, also in this case, C / C _OX approaches 1.

That is, in FIG. 4 (FIG. 7), the silicon oxide film 4
2 and the silicon semiconductor 41 have good interface characteristics,
When the voltage applied to the aluminum electrode 43 is changed from negative to positive, the value of C / C _OX changes from a value close to 1 to a value smaller than 1, and further approaches 1.

The above case is an ideal model in which the interface states are ignored, but the CV characteristics of the sample when hydrogen thermal annealing is performed at a temperature of 250 ° C. or higher in this embodiment shown in FIG. It can be seen that this ideally matches the CV characteristics.

Next, in the configuration of FIG. 4, the CV characteristic when the interface state exists at a high density between the silicon oxide film and the polycrystalline silicon film is a diagram showing an equivalent circuit of FIG. 7 will be described.

[0064] In the interface of the silicon oxide film which is a silicon semiconductor and the insulating film, if the interface state ie traps are present, the equivalent circuit is C _i of FIG. 7 will be present as a capacitor. Then, since the interface state, that is, the charge stored in the trap exists, C _i increases. And it becomes zero voltage applied to the aluminum electrode 43 of FIG. 4, even if C _D is smaller below

(Equation 3) (C / C _OX ) represented by

It does not decrease as much as (C / C _OX ) as shown by ## EQU2 ## and consequently the value of C / C _OX does not decrease more than 1.

[0065]

(Equation 3)

The behavior of the CV characteristics of the sample using the insulating film having a high interface state density can be qualitatively explained by the above model. Therefore, in the CV characteristics when the silicon oxide film in the case of not performing the thermal annealing of FIG. 4 is used in the configuration of FIG. 3, the voltage applied to the electrode 43 is 0.
The value of C / C _OX does not decrease.

[0067]

The method of the present invention for thermally annealing a silicon oxide film obtained by sputtering in a 100% oxygen atmosphere at a temperature of 250 to 350 ° C. in a 100% hydrogen atmosphere has a good interface. It was confirmed that the method was an insulating film manufacturing method for obtaining an insulating film having characteristics.

[Brief description of the drawings]

FIG. 1 shows the relationship between the interface state density of a sample manufactured in this example and the oxygen partial pressure during film formation.

FIG. 2 shows a relationship between a flat band voltage of a sample manufactured in this example and an oxygen partial pressure during film formation.

FIG. 3 shows the relationship between the breakdown voltage of the sample manufactured in this example and the oxygen partial pressure during film formation.

FIG. 4 shows a configuration of a sample manufactured in this example.

FIG. 5 shows CV characteristics of a sample manufactured in this example.

FIG. 6 shows an equivalent circuit of a sample manufactured in this example.

FIG. 7 illustrates a TFT as an example of a semiconductor device to which the structure of the present invention can be applied.

[Explanation of symbols]

 43, 44 Aluminum electrode 42 Silicon oxide film 41 Polycrystalline silicon 61 Glass substrate 62 Silicon oxide film 63 Source region 64 Channel formation region 65 Drain region 66 Silicon oxide film 67 Source electrode 68 Gate electrode 69 Drain electrode 601 Interlayer insulating film

Claims (1)

(57) [Claims] 1. A step of forming a silicon oxide film on a substrate by sputtering in an atmosphere of 100% oxygen, and the step of subjecting the silicon oxide film to hydrogen thermal annealing in a hydrogen atmosphere of 250 ° C. to 350 ° C. Method for manufacturing insulating film.