JPH09213942A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of the reliability of isolation breakdown voltage, etc., inhibiting the increase of the film thickness of a gate insulating film by the diffusion of fluorine atoms after the formation of a WSix film without reducing fluorine concentration in the WSix film constituting a gate electrode together with a polysilicon film. SOLUTION: In a MOS transistor using a polysilicon film 3 and a WSix film 4 as a gate electrode, a gate insulating film 2 consists of a silicon oxide film, into which not less than 1% nitrogen is introduced. There is fluorine in the WSix film 4, and F atoms existing in the WSix film 4 are diffused in the polysilicon film 3 by heat treatment during a MOS-transistor forming process after the formation of the WSix film 4, and reach the gate insulating film 2. Since there is not less than 1% nitrogen in the gate insulating film 2 and nitrogen strongly bonds with the bonds of silicon and oxygen atoms, replacement with F atoms is inhibited, the increase of the film thickness of the gate insulating film 2 is suppressed, and the reliability of the isolation voltage, etc., of the gate insulating film 2 is not also deteriorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a MOS structure having a polycide gate electrode and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recent ultra-LSIs are progressing with miniaturization, high density, high speed and low power consumption of elements. In the LSI process, by reducing the resistance of the polysilicon gate electrode of the MOS transistor and the polysilicon wiring, it is possible to achieve high density, high speed, and low power consumption of the device. Generally, a silicide film is used to reduce the resistance of a polysilicon gate electrode of a MOS transistor and a polysilicon wiring. This silicide film is deposited on the polysilicon film on the gate oxide film,
It is commonly used as a polycide gate electrode.
The silicide film is made of WSi _x , MoSi _x , Ti.
It is formed of various refractory metal and silicon compounds such as Si film.

A widely used silicide film at present is a WSi _x film. WSi _x films are generally monosilane (SiH ₄ ) gas and tungsten hexafluoride (W
It is formed by a CVD method formed by reacting with F ₆ ) gas, a CVD method formed by reacting dichlorosilane (SiH ₂ Cl ₂ ) gas and tungsten hexafluoride (WF ₆ ) gas, or a sputtering method.

A conventional semiconductor device will be described below with reference to the drawings. FIG. 4 shows an example of a cross-sectional structure of a conventional semiconductor device. In FIG. 4, 1 is MO
It is a silicon substrate for forming an S transistor.
Reference numeral 2'denotes a silicon oxide film, which is used as a gate oxide film in this conventional example, and hence is hereinafter referred to as a gate oxide film. Reference numeral 3 is a polysilicon film, and 4 is a WSi _x film formed on the polysilicon film 3.

As described above, this conventional semiconductor device is a polycide gate electrode in which the gate electrode is composed of the polysilicon film 3 and the WSi _x film 4 formed thereon. The WSi _x film 4 is formed of monosilane (Si
It is formed by reacting H ₄ ) gas with tungsten hexafluoride (WF ₆ ) gas. Here, when a WSi _x film is deposited to a thickness of 150 nm on a polysilicon film having a thickness of 150 nm, a sheet resistance of about 6 to 8 Ω / □ is finally obtained, which is about 1/100 of that of a case where only a polysilicon film is deposited to a thickness of 300 nm. The resistance can be reduced to 10 or less. By thus depositing the WSi _x film on the polysilicon film, it is possible to reduce the resistance of the polysilicon gate electrode of the MOS transistor and the polysilicon wiring, and to achieve high density, high speed and low power consumption of the device. You can

[0006]

However, in the semiconductor device shown in FIG. 4, the WSi _x film 4 is formed of monosilane (S).
Since iH ₄ ) gas is reacted with tungsten hexafluoride (WF ₆ ) gas to form, a large amount of F atoms are present in the WSi _x film 4. Generally monosilane (SiH
₄ ) 1 × 10 in WSi _x film 4 formed by gas
F atoms of ²⁰ atoms / cm ³ or more are present. W
Heat treatment during the MOS transistor formation process after the formation of the Si _x film 4 (for example, activation of source / drain implantation, M
By heat treatment of the interlayer film on the OS transistor), WSi
F atoms existing in the _x film 4 diffuse in the polysilicon film 3 and reach the gate oxide film 2 '. Gate oxide film 2 '
F atoms that have reached the temperature are cut and replaced with O atoms by breaking the Si—O bond of the gate oxide film 2 ′, and the separated O atoms react with the polysilicon film 3 on the gate oxide film 2 ′ to form SiO _x . In the end, however, it was confirmed that the film thickness of the gate oxide film 2'is increased (John.EJSchimitz; Semicond.
uctor World 1992.12 P216). The increase in the film thickness of gate oxide film 2'occurs not only at the interface between gate oxide film 2'and polysilicon film 3 but also at the interface between gate oxide film 2'and silicon substrate 1.

The gate oxide film 2'by such heat treatment
The phenomenon that the thickness of the gate oxide film increases is greatly affected when the thickness of the gate oxide film 2'is thinned recently. If the gate oxide film 2'has a thickness of about 8 nm before the heat treatment, the heat treatment increases the thickness by about 1 nm to about 9 nm. Further, the gate oxide film 2'having an increased film thickness has a problem that reliability such as dielectric breakdown voltage is deteriorated as compared with the gate oxide film formed by the same normal oxidation of 9 nm.

Dichlorosilane (SiH ₂ Cl ₂ )
And a tungsten hexafluoride (WF ₆ ) gas are reacted to form a WSi _x film formed by a CVD method or a sputtering method, the fluorine concentration is very low, and the gate oxide film thickness is increased by the subsequent heat treatment. There is nothing to do. However, the CVD method using dichlorosilane gas has a small process window, that is, the deposition temperature of the WSi _x film by the CVD method using dichlorosilane gas is 50.
Although the temperature is 0 to 600 ° C., there is a problem that the deposition temperature changes due to a slight change in the reaction temperature. Moreover, since dichlorosilane gas is a liquefied gas, particles are easily generated and it is difficult to manage. In addition, WSi formed by the sputtering method
_{The x} film has problems such as the presence of particles.

An object of the present invention is to increase the film thickness of a gate insulating film by diffusing fluorine atoms after forming a WSi _x film without reducing the fluorine concentration in the WSi _x film that constitutes a gate electrode together with a polysilicon film. It is an object of the present invention to provide a semiconductor device which can suppress the deterioration of reliability such as breakdown voltage and a manufacturing method thereof.

[0010]

A semiconductor device according to the present invention comprises a polysilicon film formed on a silicon substrate via a gate insulating film, and a fluorine-containing WSi _x film formed on the polysilicon film. A semiconductor device having a gate electrode, wherein the gate insulating film contains nitrogen.

According to this structure, for example, even when the WSi _x film is formed by using monosilane (SiH ₄ ) gas, fluorine is diffused in the polysilicon film by the heat treatment after the film formation of the WSi _x film, and the gate is formed. Even after reaching the insulating film, since nitrogen is strongly bonded to silicon or oxygen in the gate insulating film, fluorine reaching the gate insulating film cannot break the Si—O bond of the gate insulating film, resulting in the gate insulating film. An increase in film thickness can be suppressed. Therefore, even if the gate insulating film is thinned, the film thickness of the gate insulating film does not increase due to the heat treatment, and it is possible to prevent deterioration of reliability such as withstand voltage.

A semiconductor device according to a second aspect is the semiconductor device according to the first aspect, wherein the gate insulating film is made of a silicon oxide film, and the interface between the silicon oxide film and the silicon substrate,
1% or more of nitrogen is contained in the silicon oxide film or at the interface between the silicon oxide film and the polysilicon film. According to this configuration, for example, even when the WSi _x film is formed using a monosilane (SiH ₄ ) gas, fluorine diffuses in the polysilicon film by the heat treatment after the film formation of the WSi _x film,
Even if it reaches the silicon oxide film, since nitrogen is strongly bonded to silicon or oxygen in the silicon oxide film,
Fluorine reaching the silicon oxide film is Si of the silicon oxide film.
The -O bond cannot be cut, and an increase in the silicon oxide film thickness can be suppressed. Therefore, even if the gate insulating film made of a silicon oxide film containing 1% or more of nitrogen is thinned, the film thickness of the gate insulating film does not increase due to the heat treatment, and it is possible to prevent deterioration of reliability such as withstand voltage.

According to a third aspect of the present invention, in the semiconductor device according to the first aspect, the gate insulating film is a silicon oxide film and a oxynitride film (Si _x O _y N _z film) formed thereon.
Consists of According to this configuration, for example, even when the WSi _x film is formed using a monosilane (SiH ₄ ) gas, fluorine is diffused in the polysilicon film by the heat treatment after the film formation of the WSi _x film, and the gate insulating film is formed. even reach the upper layer of the Si _x O _y N _z film constituting, since the Si _x O _y N _z film are strongly bonded nitrogen and silicon or oxygen, substituted with fluorine is suppressed, a gate insulating film thickness Can be suppressed. Therefore, even if the gate insulating film is thinned, the film thickness of the gate insulating film does not increase due to the heat treatment, and it is possible to prevent deterioration of reliability such as withstand voltage.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor device.
A polysilicon film formed on a silicon substrate via a gate insulating film and WSi containing fluorine formed on the polysilicon film
_A method of manufacturing a semiconductor device having a gate electrode composed of an _x film, the method comprising: oxidizing a surface of a silicon substrate to form a silicon oxide film; A step of introducing nitrogen into the surface of the film to form a gate insulating film made of a silicon oxide film containing nitrogen, a step of depositing a polysilicon film on the gate insulating film, and a step of depositing a polysilicon film on the polysilicon film by a CVD method. Depositing a WSi _x film containing fluorine.

According to this manufacturing method, for example, even when the WSi _x film is formed by the CVD method using a monosilane (SiH ₄ ) gas, fluorine is generated in the polysilicon film by the heat treatment after forming the WSi _x film. Even if it diffuses and reaches the silicon oxide film, since nitrogen is strongly bonded to silicon or oxygen in the silicon oxide film, fluorine reaching the silicon oxide film can break the Si-O bond of the silicon oxide film. Therefore, the increase in the silicon oxide film thickness can be suppressed. Therefore, even if the gate insulating film made of a silicon oxide film containing nitrogen is thinned, the film thickness of the gate insulating film does not increase due to the heat treatment, and it is possible to prevent deterioration of reliability such as withstand voltage.

A method of manufacturing a semiconductor device according to claim 5 is
The method of manufacturing a semiconductor device according to claim 4, wherein the method of introducing nitrogen into the silicon oxide film is a nitriding oxidation method using N ₂ O gas. According to the nitriding oxidation method using the N ₂ O gas, nitrogen atoms can be easily introduced into the interface between the silicon oxide film and the silicon substrate and the interface between the polysilicon film and the silicon oxide film.

A method of manufacturing a semiconductor device according to claim 6 is
The method of manufacturing a semiconductor device according to claim 4, wherein the method of introducing nitrogen into the silicon oxide film is nitriding with NH ₃ gas. By nitriding with the NH ₃ gas, nitrogen atoms can be easily introduced into the interface between the silicon oxide film and the silicon substrate and the interface between the polysilicon film and the silicon oxide film.

A method of manufacturing a semiconductor device according to claim 7 is
A polysilicon film formed on a silicon substrate via a gate insulating film and WSi containing fluorine formed on the polysilicon film
_A method of manufacturing a semiconductor device having a gate electrode composed of an _x film, the surface of a silicon substrate being oxidized to form a silicon oxide film, and a nitride oxide film (Si
_x O _y N _z film) to form a gate insulating film composed of a laminated film of a silicon oxide film and a oxynitride film,
Depositing a polysilicon film on the gate insulating film, C
WS containing fluorine on the polysilicon film by VD method
depositing an i _x film.

According to this manufacturing method, for example, monosila
(SiH_Four) WSi with gas _xWhen forming a film
But WSi_xFluorine is removed by heat treatment after film formation.
Upper layer that diffuses in the silicon film and forms the gate insulating film
Si_xO_yN_zEven if it reaches the film, Si_xO_yN_zWith a membrane
Nitrogen has a strong bond with silicon or oxygen.
Therefore, substitution with fluorine is suppressed and the gate insulating film thickness increases.
Can be suppressed. Therefore, the gate insulating film is thinned.
Even if the heat treatment does not increase the thickness of the gate insulating film,
It is possible to prevent deterioration of reliability such as pressure.

A method of manufacturing a semiconductor device according to claim 8 is
The method for manufacturing a semiconductor device according to claim 7, wherein the oxynitride film (Si _x O _y N _z film) is CVD using NH ₃ gas.
It is characterized by being deposited by the method. Thus, NH
_A nitride oxide film (Si _x O _y
N _z film) can be easily deposited.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The first embodiment of the present invention will be described below.
The semiconductor device in the state will be described with reference to FIG. Figure 1
An example of the cross-sectional structure of the semiconductor device according to the first embodiment
It shows. In FIG. 1, 1 is a MOS transistor
It is a silicon substrate for forming a star. 2 is the gate
It is an insulating film and has a film thickness of 7 nm. This gate insulation film
2 oxidizes the surface of the silicon substrate 1 in an oxygen atmosphere
And then N_TwoO atmosphere or NH _ThreeNitrogen depending on the atmosphere
It is formed by introducing 1% or more. 3 is a polysilicon film
Yes, it is used as a gate electrode. 4 is polysilicon
WSi formed on the film 3 _xMembrane, monosilane (S
iH_Four) Gas and tungsten hexafluoride (WF₆) Gas
It is formed by the used CVD method.

This semiconductor device is a MOS transistor having the polysilicon film 3 and the WSi _x film 4 as gate electrodes, and the gate insulating film 2 is made of a silicon oxide film containing 1% or more of nitrogen. . Nitrogen is introduced into the interface between the gate insulating film 2 and the silicon substrate 1, the inside of the gate insulating film 2, or the interface between the gate insulating film 2 and the polysilicon film 3.

In the case of this semiconductor device, about 1 × 10 ²⁰ atoms / cm ³ or more of fluorine is present in the WSi _x film 4. Therefore, the heat treatment in WSi _x film 4 after forming MOS transistor forming step, F atoms present in WSi _x film 4 spreads the polysilicon film 3 medium, reaching the gate insulating film 2. However, in this embodiment, 1% or more of nitrogen is present in the gate insulating film 2 or at the interface thereof, and is strongly bonded to bonds of silicon and oxygen atoms, and therefore substitution with F atoms is suppressed. Therefore,
It is possible to suppress an increase in the film thickness of the gate insulating film 2 due to the heat treatment after forming the WSi _x film 4, and the reliability of the gate insulating film 2 such as withstand voltage does not deteriorate.

In the silicon oxide film which is used as the gate insulating film 2 by introducing nitrogen, conventionally, the O atom replaced with the F atom is not the O atom completely bonded to SiO ₂ ,
S existing at the interface between the silicon oxide film and the polysilicon film 3 or at the interface between the silicon oxide film and the silicon substrate 1.
i-O bond (not complete SiO ₂ but incomplete Si
_x O _y ). Therefore, nitrogen is more likely to exist in the interface between the silicon oxide film and polysilicon film 3 than in the SiO ₂ film,
A higher effect can be obtained by introducing it into the interface between the silicon oxide film and the silicon substrate 1.

In this embodiment, the gate insulating film
2 was a silicon oxide film containing 1% or more nitrogen.
However, on a normal silicon oxide film that does not introduce nitrogen
Nitride oxide film (Si_xO_yN_zFilm) to form normal
Con oxide film and oxynitride film (Si _xO_yN_zMembrane)
It may be a laminated film. In this case, WSi_xPresent in membrane 4
The existing F atoms diffuse in the polysilicon film 3 by heat treatment.
Then, even if the gate insulating film 2 is reached, the gate insulating film 2 is formed.
Upper layer nitrided oxide film (Si_xO_yN_zFilm) is a nitrogen atom
Is strongly bonded to the bonds of silicon and oxygen atoms.
Therefore, substitution with F atom is suppressed, and the same effect is obtained.
You.

The nitrogen introduced into the silicon oxide film is
If it is 1% or more, a preferable effect is obtained, but if it is 2% or more, an even more preferable effect is obtained. The structure of the gate insulating film 2 in the above embodiment is WSi.
_A remarkable effect is shown when the fluorine in the _x film 4 is 1 × 10 ¹⁹ atoms / cm ³ or more.

Next, a method of manufacturing a semiconductor device according to the second embodiment of the present invention will be described with reference to FIG. FIG.
3A to 3C are process cross-sectional views showing the method of manufacturing the semiconductor device of FIG. 1 described in the first embodiment. In FIG. 2, 2'denotes a silicon oxide film, and those corresponding to those in FIG. 1 are designated by the same reference numerals.

First, as shown in FIG. 2A, the silicon substrate 1 is oxidized in an oxygen atmosphere to form a silicon oxide film 2 '. Next, as shown in FIG. 2B, the silicon oxide film 2'is annealed in an NH ₃ atmosphere or an N ₂ O atmosphere, and nitrogen is introduced into the silicon oxide film 2'at 1% or more to form a gate insulating film. 2, and the film thickness at this time is controlled to 7 nm. Next, as shown in FIG. 2C, a polysilicon film 3 is deposited to a thickness of 150 nm on the gate insulating film 2.
This polysilicon film 3 is a doped polysilicon film doped with phosphorus in-situ. The phosphorus concentration in the polysilicon film 3 is controlled to 5 × 10 ²⁰ atoms / cm ³ . Next, as shown in FIG. 2D, monosilane (Si) is formed on the polysilicon film 3 by the CVD method.
H ₄ ) gas is reacted with tungsten hexafluoride (WF ₆ ) gas to form a WSi _x film 4 having a film thickness of 150 nm.

By this method of manufacturing a semiconductor device, the semiconductor device of FIG. 1 described in the first embodiment can be manufactured.
Therefore, as described in the first embodiment, 1% or more of nitrogen is present in the gate insulating film 2 and is strongly bonded to the bonds of silicon and oxygen atoms, so that the substitution with F atoms is suppressed. It Therefore, the MO after the WSi _x film 4 is formed
It is possible to suppress an increase in the film thickness of the gate insulating film 2 due to heat treatment during the S transistor formation process,
Also, the reliability such as the withstand voltage does not deteriorate.

In this embodiment, nitrogen is introduced into the silicon oxide film 2'in the N ₂ O atmosphere or the NH ₃ atmosphere to form the gate insulating film 2. However, as the nitrogen introducing method, an ion implantation method or the like may be used. Other methods may be used. Further, in this embodiment, nitrogen is introduced into the silicon oxide film 2 ', but as described in the first embodiment, the interface between the silicon oxide film 2' (gate insulating film 2) and the silicon substrate 1 is improved. , Or silicon oxide film 2 '
Nitrogen may be introduced into the interface between the (gate insulating film 2) and the polysilicon film 3.

Finally, a method of manufacturing a semiconductor device according to the third embodiment of the present invention will be described with reference to FIG. 3A to 3D are process cross-sectional views showing a method for manufacturing a semiconductor device when the gate insulating film described in the first embodiment is a laminated film including a silicon oxide film and a oxynitride film (Si _x O _y N _z film). It is a figure. In FIG. 3, 2'is a silicon oxide film, 5
Is a oxynitride film (Si _x O _y N _z film), and those corresponding to those in FIG.

First, as shown in FIG. 3A, the silicon substrate 1 is oxidized in an oxygen atmosphere to form a silicon oxide film 2 '. Next, as shown in FIG. 3B, a nitride oxide film (Si _x O _y N _z film) 5 is deposited on the silicon oxide film 2 ′ by the CVD method using NH ₃ gas. After that, the polysilicon film 3 shown in FIG.
The WSi _x film 4 shown in (d) is formed in the same manner as in FIGS. 2 (c) and 2 (d).

According to this method of manufacturing a semiconductor device, the first
As described in the embodiment, the gate insulating film 2 is
Conoxide film 2'and nitride oxide film (Si_xO_yN_zMembrane) 5 and
It is possible to manufacture a semiconductor device having a laminated film of. This place
WSi_xThe F atoms present in the film 4 are
It diffuses in the silicon film 3 and reaches the gate insulating film 2.
Also the nitride oxide film (Si_xO_yN_zThe film 5 has a nitrogen atom
Because it is strongly bonded to the bonds of the recon and oxygen atoms, F
Substitution with atoms is suppressed. Therefore, WSi _xMembrane 4
Heat treatment during MOS transistor formation process after formation
The increase in the thickness of the gate insulating film 2 due to the
The reliability such as the withstand voltage of the gate insulating film 2 does not deteriorate.

[0034]

As described above, according to the present invention, a gate electrode composed of a polysilicon film formed on a silicon substrate via a gate insulating film and a fluorine-containing WSi _x film formed thereon is formed. A semiconductor device having the same and a manufacturing method thereof, wherein the gate insulating film contains nitrogen.
The gate insulating film is, for example, a silicon oxide film containing 1% or more of nitrogen, or a laminated film including a silicon oxide film containing no nitrogen and a Si _x O _y N _z film formed thereon. . Here, for example, monosilane (SiH
₄ ) Even if a WSi _x film is formed using gas, WS
Even _if fluorine diffuses in the polysilicon film and reaches the gate insulating film due to the heat treatment after the formation of the i _x film, nitrogen is strongly bonded to silicon or oxygen in the gate insulating film. Fluorine reaching the film cannot cut the Si—O bond of the gate insulating film and can suppress an increase in the gate insulating film thickness. Therefore, even if the gate insulating film is thinned, the film thickness of the gate insulating film does not increase due to the heat treatment, and it is possible to prevent deterioration of reliability such as withstand voltage.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a process sectional view showing the manufacturing method of the semiconductor device according to the second embodiment of the invention.

FIG. 3 is a process sectional view showing a method of manufacturing a semiconductor device according to a third embodiment of the present invention.

FIG. 4 is a structural cross-sectional view of a semiconductor device in a conventional example.

[Explanation of symbols]

1 Silicon Substrate 2'Silicon Oxide Film 2 Gate Insulation Film 3 Polysilicon Film 4 WSi _x Film 5 Nitride Oxide Film (Si _x O _y N _z Film)

Claims (8)

[Claims] 1. A semiconductor device having a gate electrode composed of a polysilicon film formed on a silicon substrate via a gate insulating film and a fluorine-containing WSi _x film formed on the polysilicon film, wherein the gate insulating film is formed. A semiconductor device, wherein the film contains nitrogen. 2. The gate insulating film is made of a silicon oxide film, and nitrogen is 1% or more at the interface of the silicon oxide film with the silicon substrate, the interface of the silicon oxide film or the interface of the silicon oxide film with the polysilicon film. The semiconductor device according to claim 1, which contains. 3. The semiconductor device according to claim 1, wherein the gate insulating film comprises a silicon oxide film and a oxynitride film (Si _x O _y N _z film) formed thereon. 4. A method of manufacturing a semiconductor device having a gate electrode composed of a polysilicon film formed on a silicon substrate via a gate insulating film, and a WSi _x film containing fluorine formed thereon. The surface of the silicon substrate is oxidized to form a silicon oxide film, and nitrogen is introduced into the interface of the silicon oxide film with the silicon substrate, the silicon oxide film or the surface of the silicon oxide film to contain silicon containing nitrogen. Forming the gate insulating film made of an oxide film, depositing a polysilicon film on the gate insulating film, and depositing the fluorine-containing WSi _x film on the polysilicon film by a CVD method. A method of manufacturing a semiconductor device, comprising: 5. The method of manufacturing a semiconductor device according to claim 4, wherein the method of introducing nitrogen into the silicon oxide film is a nitriding oxidation method using N ₂ O gas. 6. The method of manufacturing a semiconductor device according to claim 4, wherein the method of introducing nitrogen into the silicon oxide film is nitriding with NH ₃ gas. 7. A method of manufacturing a semiconductor device having a gate electrode composed of a polysilicon film formed on a silicon substrate via a gate insulating film, and a WSi _x film containing fluorine formed thereon, The surface of the silicon substrate is oxidized to form a silicon oxide film, and a oxynitride film (Si _x O _y N) is formed on the silicon oxide film.
_z film) to form a gate insulating film formed of a laminated film of the silicon oxide film and the nitride oxide film; a step of depositing a polysilicon film on the gate insulating film; and a CVD method. And a step of depositing the fluorine-containing WSi _x film on the polysilicon film. 8. The nitrided oxide film (Si _x O _y N _z film) is NH
8. The method of manufacturing a semiconductor device according to claim 7, wherein the semiconductor device is deposited by a CVD method using ₃ gas.