JP2008300728A - Semiconductor device, and method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device for reducing characteristic deterioration due to the charge trap of an SW nitride film and any adverse effect on the characteristics due to the residual SW oxide film. <P>SOLUTION: A gate oxide film 2 and a gate electrode 3 are formed on an Si substrate 1, and a first side wall (SW) oxide film 4 is formed so as to be brought into contact with the side wall of the gate oxide film 2 and the side wall of the gate electrode 3 by a thermal oxidation method, and a second SW oxide film 5 is built up on the outside by a CVD method, and SW etching is carried out, and a third SW oxide film 6 is formed so that the first SW oxide film 4 and the second SW oxide film 5 can be covered. An SW nitride film 7 is formed on that, and a fourth SW oxide film 8 is formed on that, and SW etching is carried out so that it is possible to form a side wall having a shape whose thickness from the side wall of the gate oxide film 2 is larger, and whose thickness from the side wall of the gate electrode 3 is decreased according as it is separated from the Si substrate 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.

  8A to 8C and FIGS. 9A to 9C are process explanatory views schematically showing a conventional method for manufacturing a semiconductor device (see, for example, Patent Document 1). In the conventional manufacturing method, as shown in FIG. 8A, a gate oxide film 12 is formed on a silicon (Si) substrate 11, and polysilicon serving as a gate electrode 13 is deposited thereon, and then As shown in FIG. 8B, a pattern of the gate oxide film 12 and the gate electrode 13 is formed by a photolithography technique and / or a dry etching technique. Next, in order to form the sidewall (SW), as shown in FIG. 8C, the SW oxide film 14 and the SW oxide film 15 are formed in order, and as shown in FIG. An SW nitride film 16 and an SW oxide film 17 are sequentially formed. Thereafter, as shown in FIG. 9B, the SW oxide film 17, the SW nitride film 16, the SW oxide film 15, and the SW oxide film 14 are partially removed by a dry etching technique to form SW. Thereafter, as shown in FIG. 9C, a drain region 18 and a source region 19 are formed in the Si substrate 11 by impurity implantation.

JP 2003-264247 A

In the semiconductor device, when a voltage is applied to the gate electrode 13 and an electrical stress is applied to the inside of the device, hot electrons are generated at a high electric field such as near the side wall of the gate oxide film 12. When the hot electrons enter the SW nitride film 16 and become charge traps, the characteristics of the semiconductor device may be deteriorated (that is, hot carrier (HC) characteristics are deteriorated). Therefore, the conventional semiconductor device, as shown in FIG. 10, SW oxide film 14 and SW by thickening the total film thickness T ₂ of the oxide film 15, SW nitride film 16 from the sidewall of the gate oxide film 12 and as long as possible the distance D ₂ to, it is necessary to hardly occurs charge traps at SW nitride film 16.

However, when increasing the total thickness T ₂ of the SW oxide film 14 and the SW oxide film 15, the etching step shown in FIG. 9 (b), the remaining film 20 is easily generated as shown in FIG. 11 . This is because when the SW oxide film 14 and the SW oxide film 15 are etched, the etching selection ratio of the SW oxide film 14 to the Si substrate 11 cannot be increased. When the etching of the oxide film 14 needs to be stopped and the film thickness to be etched (here, the total film thickness T ₂ of the SW oxide film 14 and the SW oxide film 15) is thick, An error between the etching depth obtained from the etching time and the actual film thickness to be etched increases. The remaining film 20 on the silicon substrate 11 affects the depth of the source region 19 and the drain region 20 formed by impurity implantation performed thereafter, and has a problem of adversely affecting the characteristics of the semiconductor device.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and its purpose is to deteriorate characteristics due to charge trapping of the sidewall nitride film and characteristics due to the remaining film of the sidewall oxide film. An object of the present invention is to provide a semiconductor device and a method for manufacturing the semiconductor device that can reduce both adverse effects on the semiconductor device.

  The semiconductor device of the present invention includes a semiconductor substrate, a gate oxide film formed on the semiconductor substrate, a gate electrode formed on the gate oxide film, a sidewall of the gate oxide film on the semiconductor substrate, and A sidewall formed in contact with the sidewall of the gate electrode, and the sidewall is formed on the semiconductor substrate from an oxide film formed in contact with the sidewall of the gate oxide film and the sidewall of the gate electrode. A first sidewall portion, and a second sidewall portion made of a sidewall nitride film formed outside the first sidewall portion, wherein the first sidewall portion is the gate The thickness from the side wall of the oxide film is large, and the thickness from the side wall of the gate electrode decreases as the distance from the semiconductor substrate increases.

  According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising: forming a gate oxide film on a semiconductor substrate; forming a gate electrode on the gate oxide film; and forming the gate oxide film on the semiconductor substrate. Forming a sidewall on the sidewall and the sidewall of the gate electrode, and the step of forming the sidewall includes forming an oxide film on the semiconductor substrate in contact with the sidewall of the gate oxide film and the sidewall of the gate electrode. Forming a first sidewall portion having a shape in which the thickness from the side wall of the gate oxide film is large and the thickness from the side wall of the gate electrode decreases as the distance from the semiconductor substrate increases. And forming a second sidewall portion made of a sidewall nitride film in contact with the outside of the first sidewall portion. .

  According to the semiconductor device and the method of manufacturing the same of the present invention, the first sidewall portion existing inside the sidewall nitride film has a large thickness from the side wall of the gate oxide film, and the gate electrode is further away from the semiconductor substrate. Since the thickness from the side wall is reduced, the distance from the side wall of the gate oxide film to the side wall nitride film can be increased. As a result, charge traps due to hot electrons generated at high electric field locations such as near the sidewalls of the gate oxide film are unlikely to occur, and the rate of deterioration of the characteristics of the semiconductor device due to the charge traps Can be reduced.

  Further, according to the semiconductor device and the manufacturing method thereof of the present invention, even when the distance from the sidewall of the gate oxide film to the sidewall nitride film is increased, the semiconductor device is interposed between the semiconductor substrate and the sidewall nitride film. Since the thickness of the sidewall oxide film can be reduced, it is easy to manufacture without leaving the sidewall oxide film remaining on the semiconductor substrate, and there is an adverse effect on the characteristics caused by the sidewall oxide film remaining. Can be reduced.

<First Embodiment>
1A to 1C, FIGS. 2A to 2C, and FIGS. 3A to 3C schematically illustrate a method for manufacturing a semiconductor device according to the first embodiment of the present invention. It is process explanatory drawing shown in FIG. FIG. 3C is a cross-sectional view schematically showing the configuration of the semiconductor device according to the first embodiment of the present invention.

  First, the configuration of the semiconductor device according to the first embodiment will be described with reference to FIG. As shown in FIG. 3C, the semiconductor device of the first embodiment is a MOSFET, and a silicon (Si) substrate 1 that is a semiconductor substrate, a gate oxide film 2 formed on the Si substrate 1, and A gate electrode 3 made of polysilicon formed on the gate oxide film 2, and a side wall (SW) formed on the Si substrate 1 in contact with the side wall of the gate oxide film 2 and the side wall of the gate electrode 3. Have.

  The SW is configured by configurations 4 to 8 shown in FIG. In the example shown in FIG. 3C, SW is formed on the Si substrate 1 in contact with the side wall of the gate oxide film 2 and the side wall of the gate electrode 3, and the first SW oxide film 4. The second SW oxide film 5 formed in contact with the outside of the SW oxide film 4 and the third SW oxide film formed so as to cover the first SW oxide film 4 and the second SW oxide film 5 6, SW nitride film 7 formed in contact with the outside of third SW oxide film 6, and fourth SW oxide film 8 formed in contact with the outside of SW nitride film 7. In the present application, for the sake of convenience, in the configuration of the SW, the portion inside the SW nitride film 7 is the “first SW portion”, the SW nitride film 7 is the “second SW portion”, and the SW nitride film A portion outside 7 is also referred to as a “third SW portion”.

  The first SW oxide film 4 is, for example, a silicon oxide film made of an oxide generated by a thermal oxidation method, and the second SW oxide film 5 is deposited by, for example, a CVD (chemical vapor deposition) method. The third SW oxide film 6 is a silicon oxide film made of an oxide deposited by a CVD method or an oxide produced by a thermal oxidation method, for example. The SW nitride film 7 is, for example, a silicon nitride film made of nitride deposited by a CVD method. For example, the fourth SW oxide film 8 is a silicon oxide film made of an oxide deposited by a CVD method.

  Next, with reference to FIGS. 1A to 1C, FIGS. 2A to 2C, and FIGS. 3A to 3C, the method for manufacturing the semiconductor device according to the first embodiment is described. Will be explained. In the first embodiment, first, an active region is formed on a Si substrate 1 by a known method, and then a gate oxide film 2 is generated by a thermal oxidation method as shown in FIG. Next, polysilicon to be the gate electrode 3 is deposited by the CVD method. Next, as shown in FIG. 1B, patterns of the gate oxide film 2 and the gate electrode 3 are formed by using a photolithography technique and / or a dry etching technique. In FIG. 1B, the gate oxide film 2 and the gate electrode 3 are completely removed from the region on the Si substrate 1 other than the pattern of the gate oxide film 2 and the gate electrode 3 shown in FIG. However, the remaining film of the gate oxide film 2 may be thinly formed on the Si substrate 1 (just before etching removal reaches the surface of the Si substrate 1). Next, as shown in FIG. 1C, a first SW oxide film 4 is generated by a thermal oxidation method, and then a second SW oxide film 5 is deposited by a CVD method.

Next, as shown in FIG. 2A, an SW portion including the first SW oxide film 4 and the second SW oxide film 5 is formed by a dry etching technique. For convenience, the etching at this time is referred to as “first SW etching process”. FIG. 2A shows a case where the first SW oxide film 4 is completely removed from a region on the Si substrate 1 other than the pattern shown in FIG. The remaining film of the first SW oxide film 4 may be thinly left on the Si substrate 1 (just before etching removal reaches the surface of the Si substrate 1). Next, as shown in FIG. 2B, the SW portion made of the first SW oxide film 4 and the second SW oxide film 5 has desired characteristics by wet etching technology or chemical dry etching technology. Shape. For convenience, the etching at this time is referred to as “second SW etching process”. However, the first SW etching process and the second SW etching process may be performed in one step. FIG. 2B shows the case where the first SW oxide film 4 is completely removed from the region on the Si substrate 1 other than the pattern shown in FIG. The remaining film of the first SW oxide film 4 may be thinly left on the Si substrate 1 (just before etching removal reaches the surface of the Si substrate 1). Next, as shown in FIG. 2C, the SW portion composed of the first SW oxide film 4 and the second SW oxide film 5, the gate electrode 3, and the Si substrate by CVD or thermal oxidation. A third SW oxide film 6 is formed to cover 1. In the first embodiment, the SW portion composed of the first SW oxide film 4 and the second SW oxide film 5 can increase the distance from the sidewall of the gate oxide film 2 to the SW nitride film 7. , the thickness _{T 1} of the third SW oxide film 6 may be thinner. The film thickness T ₁ of the third SW oxide film 6 can be made thinner than, for example, the first SW oxide film 4 or the second SW oxide film 5.

  Next, as shown in FIG. 3A, a SW nitride film 7 is deposited on the outside of the third SW oxide film 6 by the CVD method, and then the SW nitride film 7 is deposited on the outside of the SW nitride film 7 by the CVD method. 4 SW oxide film 8 is deposited. Next, as shown in FIG. 3B, the fourth SW oxide film 8 and the SW nitride film 7 are etched by a dry etching technique, and the third SW oxide film 6 is further etched to form SW. To do. For convenience, the etching at this time is referred to as “third SW etching process”. Next, as shown in FIG. 3C, impurities are implanted into the Si substrate 1 to form a drain region 9 and a source region 10 in the Si substrate 1.

  As shown in FIG. 2C, in the above description, the first sidewall portion formed of the SW oxide films 4 and 5 is formed on the first sidewall region 1a of the Si substrate 1. Although the case where it is formed is described, the first sidewall portions 4 and 5 on the first sidewall region 1a are oxide films (or stacked oxide films) composed of one layer or three or more layers. These may be referred to as “first oxide film” for convenience.

  Further, as shown in FIG. 3B, on the first sidewall region 1a of the Si substrate 1 and on the second sidewall region 1b, which is a region surrounding the outside of the first sidewall region 1a. Alternatively, a third SW oxide film 6 covering the SW portions (first oxide films) 4 and 5 made of the first SW oxide films 4 and 5 may be formed. When the SW oxide films 4 and 5 are collectively referred to as “first oxide film”, the SW oxide film 6 is referred to as “second oxide film” for convenience. In the step of forming the second sidewall portion 7, the second sidewall portion 7 is formed on the first sidewall region 1 a and the second sidewall region 1 b so as to cover the SW oxide film 6.

FIG. 4 is a diagram for explaining the effects of the semiconductor device and the manufacturing method thereof according to the first embodiment. As shown in FIG. 4, according to the semiconductor device of the first embodiment and the manufacturing method thereof, the first SW oxide film 4 and the second SW on the first sidewall region 1 a of the Si substrate 1. Since the SW portion made of the oxide film 5 can increase the film thickness from the side wall of the gate oxide film 2 (the thickness in the horizontal direction in FIG. 4), the second sidewall of the third SW oxide film 6 can be made. even a small thickness T ₁ of the region 1b, it is possible to increase the distance D ₁ of the from the side wall of the gate oxide film 2 until SW nitride film 7. Therefore, according to the first embodiment, even if the third SW oxide film 6 is thin, the first sidewall portion existing inside the SW nitride film 7 is the side wall of the gate oxide film 2. 4 (the horizontal thickness in FIG. 4) is large, and the thickness from the side wall of the gate electrode 3 (the horizontal thickness in FIG. 4) decreases as the distance from the Si substrate 1 increases. The distance from the sidewall of the gate oxide film 3 to the SW nitride film 7 can be increased. As a result, it is difficult for charge traps to occur due to hot electrons generated in a high electric field such as the vicinity of the side wall of the gate oxide film 3 entering the SW nitride film 7, and the deterioration of the characteristics of the semiconductor device due to the charge traps occurs. The rate can be reduced.

Further, according to the semiconductor device and the manufacturing method thereof of the first embodiment, the second SW region 6b on the second sidewall region 1b of the third SW oxide film 6 interposed between the Si substrate 1 and the sidewall nitride film 7 is used. it is possible to reduce the thickness T _1, the residual film is not easily remain on the Si substrate 1, it is possible to reduce the adverse effect on the characteristics caused by the residual film of the SW oxide film. As described above, according to the first embodiment, when the thickness of the SW oxide film is increased in order to reduce the charge trap of the SW nitride film, the adverse effect due to the remaining film of the SW oxide film becomes significant. If the thickness of the SW oxide film is reduced in order to reduce the remaining SW oxide film, the trade-off that the charge trap of the SW nitride film increases can be eliminated.

<Second Embodiment>
FIG. 5 is a cross-sectional view schematically showing a semiconductor device and a manufacturing method thereof according to the second embodiment of the present invention. In FIG. 5, the same reference numerals are given to the same or corresponding components as those in FIG. In the semiconductor device according to the second embodiment, the first SW oxide film 5a in which the first SW portion existing inside the SW nitride film 7 is formed from the gate electrode 3 side by the CVD method, the thermal oxidation method, The semiconductor device according to the first embodiment shown in FIG. 3C is composed of the second SW oxide film 4a formed by the above process and the third SW oxide film 6 formed by the thermal oxidation method. Different from the device. Even when the SW oxide film formation order is changed as in the second embodiment, the same effect as in the first embodiment can be obtained.

<Third Embodiment>
FIG. 6 is a cross-sectional view schematically showing a semiconductor device and a manufacturing method thereof according to the third embodiment of the present invention. In FIG. 6, the same or corresponding components as those in FIG. In the semiconductor device according to the third embodiment, the first SW portion existing inside the SW nitride film 7 includes the fifth SW oxide film 5b formed by the CVD method and the thermal oxidation method from the gate electrode 3 side. The semiconductor device of the first embodiment shown in FIG. 3C is different from the semiconductor device of the first embodiment shown in FIG. Even when the number of SW oxide films is changed as in the third embodiment, the same effect as in the first embodiment can be obtained, and in addition, the configuration can be simplified. Obtainable.

<Fourth Embodiment>
FIG. 7 is a cross-sectional view schematically showing a semiconductor device and a manufacturing method thereof according to the fourth embodiment of the present invention. In FIG. 7, the same reference numerals are given to the same or corresponding components as those in FIG. The semiconductor device according to the fourth embodiment is that the fourth SW oxide film 8 is not provided outside the SW nitride film 7a and that the film thickness of the SW nitride film 7a is increased. It differs from the form. Even if the fourth SW oxide film 8 is not provided as in the fourth embodiment, the same effect as in the first embodiment can be obtained, and in addition, the configuration can be simplified. An effect can be obtained.

(A)-(c) is process explanatory drawing (the 1) which shows the manufacturing method of the semiconductor device which concerns on the 1st Embodiment of this invention. (A)-(c) is process explanatory drawing (the 2) which shows the manufacturing method of the semiconductor device which concerns on 1st Embodiment. (A)-(c) is process explanatory drawing (the 3) which shows the manufacturing method of the semiconductor device which concerns on 1st Embodiment, The same figure (c) is the semiconductor device which concerns on 1st Embodiment. A cross-sectional structure is shown. It is a figure for demonstrating the effect of the semiconductor device which concerns on 1st Embodiment, and its manufacturing method. It is sectional drawing which shows the structure of the semiconductor device which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the semiconductor device which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the semiconductor device which concerns on the 4th Embodiment of this invention. (A)-(c) is process explanatory drawing (the 1) which shows the manufacturing method of the conventional semiconductor device. (A)-(c) is process explanatory drawing (the 2) which shows the manufacturing method of the conventional semiconductor device. It is a figure for demonstrating the problem of the conventional semiconductor device and its manufacturing method. It is a figure for demonstrating the other problem of the conventional semiconductor device and its manufacturing method.

Explanation of symbols

1 Si substrate (semiconductor substrate),
1a first sidewall region,
1b second sidewall region,
2 gate oxide film,
3 Gate electrode (polysilicon),
4,5a first SW oxide film,
5, 4a Second SW oxide film,
6, 6b Third SW oxide film,
5b Fifth SW oxide film,
6b Sixth SW oxide film,
7, 7a SW nitride film,
8 Fourth SW oxide film,
9 Source area,
10 drain region,
T ₁ the thickness of the third SW oxide film,
D ₁ Distance from the sidewall of the gate oxide film to the SW nitride film.

Claims (22)

A semiconductor substrate;
A gate oxide film formed on the semiconductor substrate;
A gate electrode formed on the gate oxide film;
A sidewall formed on and in contact with the sidewall of the gate oxide film and the sidewall of the gate electrode on the semiconductor substrate;
The sidewall is
A first sidewall portion made of an oxide film formed on and in contact with the sidewall of the gate oxide film and the sidewall of the gate electrode on the semiconductor substrate;
A second sidewall portion made of a sidewall nitride film formed outside the first sidewall portion;
The first side wall portion has a shape in which the thickness from the side wall of the gate oxide film is large, and the thickness from the side wall of the gate electrode decreases as the distance from the semiconductor substrate increases. . The first sidewall portion is
A first sidewall oxide film formed on and in contact with a sidewall of the gate oxide film and a sidewall of the gate electrode on the semiconductor substrate;
A second sidewall oxide film formed outside the first sidewall oxide film;
A third sidewall oxide film formed to cover the first sidewall oxide film and the second sidewall oxide film;
The semiconductor device according to claim 1, wherein the second sidewall portion is formed outside the third sidewall oxide film. The first sidewall oxide film is a film made of an oxide generated by a thermal oxidation method,
The second sidewall oxide film is a film made of an oxide deposited by a CVD method,
The semiconductor device according to claim 2, wherein the third sidewall oxide film is a film made of an oxide deposited by a CVD method or an oxide generated by an oxidation method. The first sidewall oxide film is a film made of an oxide deposited by a CVD method,
The second sidewall oxide film is a film made of an oxide generated by a thermal oxidation method,
The semiconductor device according to claim 2, wherein the third sidewall oxide film is a film made of an oxide deposited by a CVD method or an oxide generated by an oxidation method. The first sidewall portion is
A fifth sidewall oxide film formed on and in contact with the sidewall of the gate oxide film and the sidewall of the gate electrode on the semiconductor substrate;
A sixth sidewall oxide film formed to cover the fifth sidewall oxide film,
The semiconductor device according to claim 1, wherein the second sidewall portion is formed outside the sixth sidewall oxide film. The fifth sidewall oxide film is a film made of an oxide deposited by a CVD method or an oxide generated by a thermal oxidation method,
The semiconductor device according to claim 5, wherein the sixth sidewall oxide film is a film made of an oxide deposited by a CVD method or an oxide generated by a thermal oxidation method.   7. The semiconductor device according to claim 1, wherein the sidewall nitride film constituting the second sidewall portion is a film deposited by a CVD method.   3. The semiconductor device according to claim 1, wherein the sidewall has a third sidewall portion made of a fourth sidewall oxide film formed outside the second sidewall portion. 4. .   9. The semiconductor device according to claim 8, wherein the fourth sidewall oxide film constituting the third sidewall portion is a film made of an oxide deposited by a CVD method. The first sidewall portion is
A first oxide film having a shape in which the thickness from the side wall of the gate oxide film is large and the thickness from the side wall of the gate electrode decreases as the distance from the semiconductor substrate increases;
The semiconductor device according to claim 1, further comprising: a second oxide film formed on the semiconductor substrate so as to cover the first oxide film. The semiconductor substrate has a first sidewall region and a second sidewall region surrounding the first sidewall region;
The first oxide film is formed on the first sidewall region so as to expose the second sidewall region,
The second oxide film is formed on the first sidewall region and the second sidewall region so as to cover the first oxide film,
The semiconductor device according to claim 10, wherein the second sidewall portion is formed on the first and second sidewall regions so as to cover the second oxide film. Forming a gate oxide film on the semiconductor substrate;
Forming a gate electrode on the gate oxide film;
Forming a sidewall on the sidewall of the gate oxide film and the sidewall of the gate electrode on the semiconductor substrate;
The step of forming the sidewall includes
On the semiconductor substrate, a first sidewall portion made of an oxide film in contact with the sidewall of the gate oxide film and the sidewall of the gate electrode has a large thickness from the sidewall of the gate oxide film and is separated from the semiconductor substrate. A step of forming the gate electrode to have a shape in which the thickness from the side wall decreases,
Forming a second sidewall portion made of a sidewall nitride film in contact with the outside of the first sidewall portion. Forming the first sidewall portion includes:
Forming a first sidewall oxide film on the semiconductor substrate in contact with the sidewall of the gate oxide film and the sidewall of the gate electrode;
Forming a second sidewall oxide film outside the first sidewall oxide film;
Forming a third sidewall oxide film so as to cover the first sidewall oxide film and the second sidewall oxide film,
13. The semiconductor device according to claim 12, wherein in the step of forming the second sidewall portion, the second sidewall portion is formed outside the third sidewall oxide film. Production method. The step of forming the first sidewall oxide film includes a step of forming a film made of an oxide by a thermal oxidation method,
The step of forming the second sidewall oxide film includes a step of forming a film made of an oxide deposited by a CVD method,
The step of forming the third sidewall oxide film includes a step of forming a film made of an oxide deposited by a CVD method or a film made of an oxide generated by an oxidation method. The manufacturing method of the semiconductor device as described in any one of Claims 1-3. The step of forming the first sidewall oxide film includes a step of forming a film made of an oxide deposited by a CVD method,
The step of forming the second sidewall oxide film includes a step of forming a film made of an oxide generated by a thermal oxidation method,
The step of forming the third sidewall oxide film includes a step of forming a film made of an oxide deposited by a CVD method or a film made of an oxide generated by an oxidation method. The manufacturing method of the semiconductor device as described in 2. above. Forming the first sidewall portion includes:
Forming a fifth sidewall oxide film on the semiconductor substrate so as to be in contact with the sidewall of the gate oxide film and the sidewall of the gate electrode;
Forming a sixth sidewall oxide film so as to cover the fifth sidewall oxide film,
13. The method of manufacturing a semiconductor device according to claim 12, wherein the step of forming the second sidewall portion includes a step of forming the sidewall nitride film outside the sixth sidewall oxide film. Method. The step of forming the fifth sidewall oxide film includes a step of forming a film made of an oxide deposited by a CVD method or an oxide generated by a thermal oxidation method,
The step of forming the sixth sidewall oxide film includes a step of forming a film made of an oxide deposited by a CVD method or an oxide generated by a thermal oxidation method. Semiconductor device manufacturing method.   18. The method according to claim 12, wherein the step of forming the sidewall nitride film constituting the second sidewall portion includes a step of depositing a sidewall nitride film by a CVD method. The manufacturing method of the semiconductor device of description.   14. The step of forming the sidewall includes a step of forming a third sidewall portion made of a fourth sidewall oxide film outside the second sidewall portion. The manufacturing method of the semiconductor device as described in any one of Claims 1-3.   20. The semiconductor according to claim 19, wherein the step of forming the fourth sidewall oxide film constituting the third sidewall portion includes a step of depositing an oxide film by a CVD method. Device manufacturing method. Forming the first sidewall portion includes:
On the semiconductor substrate, the thickness from the sidewall of the gate oxide film and the sidewall of the gate electrode is large from the sidewall of the gate oxide film, and the thickness from the sidewall of the gate electrode is farther away from the semiconductor substrate. Forming a first oxide film having a shape that reduces
The method of manufacturing a semiconductor device according to claim 12, further comprising: forming a second oxide film on the semiconductor substrate so as to cover the first oxide film. The semiconductor substrate has a first sidewall region and a second sidewall region surrounding the first sidewall region;
The step of forming the first oxide film is a step of forming the first oxide film on the first sidewall region so as to expose the second sidewall region,
The step of forming the second oxide film is a step of forming the second oxide film on the first sidewall region and the second sidewall region so as to cover the first oxide film. And
The step of forming the second sidewall portion includes forming the second sidewall portion on the first sidewall region and the second sidewall region so as to cover the second oxide film. The method of manufacturing a semiconductor device according to claim 21, wherein

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