JP2007142024A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a gate insulating film of high permittivity which is high in an average nitrogen concentration and low in the nitrogen concentration near the interface of a silicon substrate. <P>SOLUTION: A nitrated layer is formed on the silicon substrate (step S1), and, thereafter, oxidizing solution treatment is applied at first to form a low oxygen concentration interface oxidizing region between the nitrated layer and the silicon substrate (step S2), next, heat treatment in oxidizing gas atmosphere is effected to supply oxygen to the low oxygen concentration interface oxidizing region and to form a high oxygen concentration interface oxidizing region there (step S3). Oxidization employing oxidizing solution is effected prior to the heat treatment in the oxidizing gas atmosphere whereby the low oxygen concentration interface oxidizing region, formed by the oxidizing solution treatment, becomes so as to be easily oxidized upon heat treatment, and the high oxygen concentration interface oxidizing region is formed there. According to this method, forming of the gate insulating film, high in nitrogen concentration and permittivity as a whole, becomes possible while reducing the nitrogen concentration in between the nitrated film and the silicon substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a MOS (Metal Oxide Semiconductor) type semiconductor device using a gate insulating film containing nitrogen.

  In forming a gate insulating film of a MOS field effect transistor (MOSFET), nitrogen (N) is used in the gate insulating film in order to obtain a gate insulating film that is capacitively thin while suppressing gate leakage current. A technique of increasing the dielectric constant by inclusion is often used.

For example, conventionally, a method for nitriding a silicon oxide (SiO, SiO ₂ ) film formed on the surface of a silicon (Si) substrate, a method for nitriding a surface region of a silicon oxide film, and the like have been proposed. For the formation of the silicon oxide film, a wet oxidation method is used in addition to a dry oxidation method such as thermal oxidation (see Patent Documents 1 and 2).

In addition, a method is also proposed in which a silicon nitride (SiN) film is first formed on the surface of a silicon substrate, and this is heat-treated in an oxidizing gas atmosphere to form a silicon oxide film in a region between the silicon nitride film and the silicon substrate. (See Non-Patent Documents 1 and 2).
JP 2005-64052 A JP 2005-191341 A “2002 Symposium on VLSI Technology Digest of Technical Papers”, p. 202 “2004 Symposium on VLSI Technology Digest of Technical Papers”, p. 172

However, the conventional gate insulating film forming method has the following problems.
First, in the method of forming a silicon oxide film on a silicon substrate and nitriding it, if nitrogen concentration in the gate insulating film is increased to increase the dielectric constant, nitrogen penetrates the silicon oxide film. The possibility of reaching the silicon substrate increases the performance deterioration of the MOSFET due to the deterioration of the interface characteristics such as the formation of a carrier trap region and the reduction of carrier mobility.

  In order to avoid this, it is necessary to limit the nitrogen concentration of the gate insulating film to a level at which there is little risk of degrading the performance of the MOSFET. Therefore, this method sufficiently increases the dielectric constant of the gate insulating film. It is difficult to plan. Such a problem can occur in the same manner regardless of whether a dry oxidation method or a wet oxidation method is used to form the silicon oxide film.

  In order to suppress deterioration of the interface characteristics when nitrogen is contained in the gate insulating film, it is desired to reduce the nitrogen concentration at the interface with the silicon substrate while increasing the average nitrogen concentration. Conventionally, attempts have been made to nitride the surface region of a silicon oxide film. However, even when such a method is used, if the amount of nitrogen introduced increases, diffusion of nitrogen as described above occurs, and the interface characteristics are increased. It is difficult to sufficiently suppress the deterioration of the material.

  In addition, if a method of first forming a silicon nitride film over a silicon substrate and then performing heat treatment in an oxidizing gas atmosphere is used, a silicon oxide film can be formed between the silicon nitride film and the silicon substrate. Compared with the method, it can be said that the possibility of obtaining a gate insulating film having a high average nitrogen concentration and a low nitrogen concentration at the interface with the silicon substrate is increased.

  However, in this method, since a silicon oxide film is formed between the silicon nitride film and the silicon substrate by oxygen (O) that passes through the silicon nitride film, it is difficult to supply sufficient oxygen to the region. If the heat treatment temperature is increased in order to increase the diffusion rate of oxygen in the silicon nitride film, nitrogen in the silicon nitride film diffuses into the silicon substrate, and thus the temperature is limited. After all, in this method, the oxygen concentration in the interface region between the silicon nitride film and the silicon substrate cannot be increased beyond a certain amount, and as a result, the amount of nitrogen present at the interface between the gate insulating film and the silicon substrate is compared. Therefore, it is difficult to sufficiently improve the performance of the MOSFET.

  The present invention has been made in view of these points, and an object of the present invention is to provide a method for manufacturing a high-performance semiconductor device provided with a high dielectric constant gate insulating film.

  In the present invention, in order to solve the above problems, in a method for manufacturing a semiconductor device, a step of forming a nitride layer on a semiconductor substrate, and an oxidized region is formed between the nitride layer and the semiconductor substrate using an oxidizing solution. There is provided a method for manufacturing a semiconductor device, comprising a step of forming and a step of increasing the oxygen concentration in the oxidized region by performing a heat treatment in an oxidizing gas atmosphere.

  According to such a method for manufacturing a semiconductor device, after forming a nitride layer on a semiconductor substrate, an oxidation region is first formed between the nitride layer and the semiconductor substrate using an oxidizing solution, and then an oxidizing gas is formed. A heat treatment is performed in the atmosphere to increase the oxygen concentration in the oxidized region. By performing oxidation using an oxidizing solution prior to the heat treatment in the oxidizing gas atmosphere, the region between the nitride layer and the semiconductor substrate is easily oxidized during the heat treatment in the oxidizing gas atmosphere, and oxygen in the region is oxidized. The concentration can be increased effectively.

  In the present invention, after a nitride layer is formed on a semiconductor substrate, an oxidized region is first formed between the nitride layer and the semiconductor substrate using an oxidizing solution, and then the oxidized region is subjected to heat treatment in an oxidizing gas atmosphere. The oxygen concentration was increased. As a result, the oxygen concentration in the oxidized region can be effectively increased, so that a gate insulating film having a high average nitrogen concentration but a low nitrogen concentration and a high oxygen concentration is formed at the interface with the semiconductor substrate. Can do. By forming such a gate insulating film, it is possible to reduce the effective gate insulating film thickness by increasing the dielectric constant, and to realize a high-performance MOSFET having both high device performance and high reliability.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a flow of forming a gate insulating film. 2 to 4 are explanatory views of each forming process. FIG. 2 is a schematic cross-sectional view of the main part of the silicon nitride film forming process. FIG. 3 is a schematic cross-sectional view of the main part of the first oxidation process. These are the principal part cross-sectional schematic diagrams of a 2nd oxidation process.

  In forming the gate insulating film, as shown in FIGS. 1 and 2, first, a nitride layer 2 is formed on the silicon substrate 1 (step S1). The nitride layer 2 is made of silicon nitride or silicon oxynitride (SiON), and is formed, for example, by heat-treating the silicon substrate 1 in a nitriding gas atmosphere or irradiating the silicon substrate 1 with plasma containing nitrogen. be able to.

  After the formation of the nitride layer 2, as shown in FIG. 1, the silicon substrate 1 having the nitride layer 2 formed on the surface is treated with an oxidizing solution (step S2), and the interface region between the nitride layer 2 and the silicon substrate 1 is processed. Oxygen is supplied to the region to oxidize the region. In this oxidizing solution treatment, the amount of oxygen supplied to the region is small compared to thermal oxidation or the like, and a low oxygen concentration is present between the nitride layer 2 and the silicon substrate 1 as shown in FIG. An oxidized region (referred to as “low oxygen concentration interface oxidized region”) 3 is formed.

  Then, as shown in FIG. 1, after the low oxygen concentration interface oxidation region 3 is formed, heat treatment is performed in an oxidizing gas atmosphere (step S3). As a result, oxygen is supplied to the low oxygen concentration interface oxidation region 3 formed between the nitride layer 2 and the silicon substrate 1, and the low oxygen concentration interface oxidation region 3 is further oxidized. As a result, as shown in FIG. 4, between the nitride layer 2 and the silicon substrate 1, an oxidized region in which the oxygen concentration of the low oxygen concentration interface oxidized region 3 is increased (referred to as “high oxygen concentration interface oxidized region”). 4 is formed. Although not shown here, an oxide region is also formed on the nitride layer 2 depending on the heat treatment conditions during the heat treatment in the oxidizing gas atmosphere.

  As described above, in this method of forming the gate insulating film, after forming the nitride layer 2 on the silicon substrate 1, first, the low oxygen concentration interface oxide region 3 is formed between the nitride layer 2 and the silicon substrate 1 by an oxidizing solution treatment. Then, heat treatment is performed in an oxidizing gas atmosphere to increase the oxygen concentration in the low oxygen concentration interface oxidation region 3 to form the high oxygen concentration interface oxidation region 4.

  At that time, the low oxygen concentration interfacial oxidation region 3 can be formed by performing an oxidizing solution treatment at a relatively low temperature, and suppresses thermal diffusion of nitrogen from the nitride layer 2 to the silicon substrate 1 during the formation. be able to.

  Since the low oxygen concentration interface oxidation region 3 is formed using oxygen supplied to the silicon substrate 1 through the nitride layer 2 during the oxidizing solution treatment, the oxygen concentration is compared with that of a thermal oxide film or the like. It tends to be low. However, since a certain amount of oxygen is supplied in advance between the nitride layer 2 and the silicon substrate 1 in this way, the region is easily oxidized during the subsequent heat treatment in an oxidizing gas atmosphere. Become. This is because the low oxygen concentration interfacial oxidation region 3 formed on the silicon substrate 1 by the oxidizing solution treatment is in a state in which Si—Si bonds and Si—O—Si bonds are mixed, and is transmitted through the nitride layer 2. This is because a new Si—O—Si bond is easily formed by oxygen.

  Furthermore, since a certain amount of oxygen is supplied in advance to the region between the nitride layer 2 and the silicon substrate 1, the subsequent heat treatment in the oxidizing gas atmosphere can be performed only by the heat treatment under the same conditions. Compared with the case where a silicon oxide film is formed therebetween, an oxidized region having a higher oxygen concentration is formed between the nitride layer 2 and the silicon substrate 1. In other words, in the heat treatment in the oxidizing gas atmosphere after the oxidizing solution treatment, even if the amount of oxygen that permeates the nitride layer 2 is small compared to the conventional thermal oxidation or the like, it is between the nitride layer 2 and the silicon substrate 1. In addition, it becomes possible to form an oxidized region having a high oxygen concentration.

  The region between the nitride layer 2 and the silicon substrate 1 is easily oxidized during the heat treatment in the oxidizing gas atmosphere by the low oxygen concentration interface oxidation region 3, and the heat treatment in the oxidizing gas atmosphere is performed by the low oxygen concentration interface oxidation region 3. Since the amount of oxygen that permeates the nitride layer 2 does not always have to be large, the temperature of the heat treatment in the oxidizing gas atmosphere can be set low after the oxidizing solution treatment. Thereby, it is possible to suppress the thermal diffusion of nitrogen from the nitride layer 2 to the silicon substrate 1, so that the nitrogen concentration in the region between the nitride layer 2 and the silicon substrate 1 can be further reduced.

  According to such a method of forming a gate insulating film, it is possible to form a gate insulating film having a high nitrogen concentration and a high dielectric constant as a whole while keeping the nitrogen concentration in the region between the nitride layer 2 and the silicon substrate 1 low. become. If such a gate insulating film is applied to a MOSFET, the effective gate insulating film thickness can be reduced by increasing the dielectric constant. In addition, the reduction of the interface nitrogen concentration suppresses the deterioration of carrier mobility and the like, thereby increasing the operating current, and further improving the reliability by extending the life of the device. Therefore, a high-performance MOSFET can be formed.

Hereinafter, a case where the above-described gate insulating film forming method is applied to formation of a MOSFET will be specifically described.
FIG. 5 is a schematic cross-sectional view of an essential part of the element isolation region and channel impurity diffusion region forming step.

  In forming the MOSFET, first, as shown in FIG. 5, an element isolation region 11 is formed on the silicon substrate 10 by using an STI (Shallow Trench Isolation) method or the like. Next, an impurity having a predetermined conductivity type is diffused into the silicon substrate 10 in a portion that becomes a channel region of the MOSFET, for example, by performing activation annealing after ion implantation to form a channel impurity diffusion region 12.

FIG. 6 is a schematic cross-sectional view of the relevant part in the nitride layer forming step.
After the channel impurity diffusion region 12 is formed, this is subjected to a predetermined heat treatment in a predetermined nitriding gas atmosphere to form a nitride layer 13 on the surface of the channel impurity diffusion region 12. At this time, the nitride layer 13 is also formed on the element isolation region 11 at the same time.

The nitride layer 13 is, for example, heat-treated at a temperature of about 500 ° C. to about 1000 ° C. for about 1 second to about 600 seconds in a pressure-controlled nitriding gas atmosphere at a pressure range of about 0.1 Torr to about 760 Torr (1 Torr≈133 Pa). To form a channel impurity diffusion region 12 having a surface thickness of about 0.3 nm to about 2 nm. At that time, the nitriding gas may be ammonia (NH ₃ ) gas, nitrogen monoxide (NO) gas, dinitrogen monoxide (N ₂ O) gas, nitrogen dioxide (NO ₂ ) gas, or the like. A gas containing nitrogen such as a mixed gas containing two or more kinds can be widely used.

  Plasma can also be used to form the nitride layer 13. In that case, plasma containing nitrogen, such as nitrogen plasma, ammonia plasma, or nitrogen monoxide plasma, can be widely used as the plasma. Although the plasma irradiation conditions vary depending on the method, for example, the power is about 100 W to about 2000 W, the gas pressure is about 1 mTorr to 1 Torr, and the surface of the channel impurity diffusion region 12 has a thickness of about 0.3 nm to about 2 nm. Conditions are set so that the nitride layer 13 is formed.

FIG. 7 is a schematic cross-sectional view of the relevant part in the low oxygen concentration interface oxidized region forming step.
After the formation of the nitride layer 13, the substrate is immersed in a predetermined oxidizing solution under predetermined conditions to form a low oxygen concentration interface oxide region 14 having a relatively low oxygen concentration between the nitride layer 13 and the silicon substrate 10.

Examples of the oxidizing solution include an aqueous ammonia solution (ammonia concentration of about 0.5% to about 5%) / hydrogen peroxide (H ₂ O ₂ ) aqueous solution (hydrogen peroxide concentration of about 0.5% to about 5%) / A mixture of water (H ₂ O) can be used. In addition, hydrochloric acid (HCl) aqueous solution / hydrogen peroxide aqueous solution / water mixed solution, sulfuric acid (H ₂ SO ₄ ) aqueous solution / hydrogen peroxide aqueous solution / water mixed solution, nitric acid (HNO ₃ ) aqueous solution / peroxide A hydrogen aqueous solution / water mixture or the like can also be used.

  When the substrate is immersed in such an oxidizing solution, for example, the type of oxidizing solution used so that the low oxygen concentration interfacial oxidation region 14 having a thickness of about 0.1 nm to about 1 nm is formed on the surface of the silicon substrate 10. The liquid temperature is appropriately set in the range of room temperature to about 50 ° C., and the immersion time is appropriately set in the range of about 30 seconds to about 300 seconds. In addition, since the immersion is performed in a low temperature environment as described above, the nitrogen contained in the nitride layer 13 hardly diffuses when forming the low oxygen concentration interface oxidized region 14.

  After immersion, the oxidizing solution is washed with water, and then the substrate is dried using isopropyl alcohol (IPA) at a temperature of about 50 ° C. to about 100 ° C. In addition, since this drying is performed in a low-temperature environment as in the case of immersion, nitrogen hardly diffuses from the nitride layer 13.

FIG. 8 is a schematic cross-sectional view of an essential part of the high oxygen concentration interface oxidized region forming step.
After drying, for example, heat treatment is performed at a temperature of about 700 ° C. to about 1100 ° C. for about 1 second to about 600 seconds in an oxidizing gas atmosphere with a pressure range of about 0.1 Torr to about 760 Torr. As a result, oxygen is supplied to the low oxygen concentration interface oxide region 14 through the nitride layer 13 to increase the oxygen concentration, and a high oxygen concentration interface oxide region 15 is formed there. As the oxidizing gas at the time of heat treatment, nitrogen monoxide gas, dinitrogen monoxide gas, nitrogen dioxide gas, oxygen (O ₂ ) gas, etc., or a mixed gas containing two or more kinds of such gases may be used. it can.

  Prior to this heat treatment, a low oxygen concentration interface oxidized region 14 that is relatively easily oxidized is formed between the nitride layer 13 and the silicon substrate 10. When a predetermined heat treatment is performed from this state in a predetermined oxidizing gas atmosphere, the low oxygen concentration interface oxidized region 14 is easily oxidized with oxygen that has passed through the nitride layer 13 as described above. In addition, since the low oxygen concentration interface oxidation region 14 contains a certain amount of oxygen before the oxidation, the amount of oxygen transmitted through the nitride layer 13 is not necessarily limited to form such a high oxygen concentration interface oxidation region 15. You don't need to do much. Therefore, it is not necessary to significantly increase the heat treatment temperature in order to form an oxidized region having a high oxygen concentration between the nitride layer 13 and the silicon substrate 10, and as a result, the amount of nitrogen from the nitride layer 13 is less than that in the conventional thermal oxidation. It becomes possible to suppress thermal diffusion significantly.

  The oxygen concentration in the high oxygen concentration interface oxidation region 15 is 46% or more in terms of the number ratio of silicon, oxygen, and nitrogen, and the nitrogen concentration is similarly less than 20% in terms of the number of atoms. It is also possible to suppress the nitrogen concentration in the high oxygen concentration interfacial oxidation region 15 to less than 5% in terms of the number ratio of silicon, oxygen, and nitrogen. In this case, the oxygen concentration is similarly 61% or more in terms of the number of atoms.

  When a gas containing nitrogen such as a monoxide gas is used as the oxidizing gas when forming the high oxygen concentration interface oxidation region 15, nitriding occurs simultaneously with the oxidation, and an oxidizing gas containing no nitrogen is used. Compared to the case, the nitrogen concentration of the nitride layer 13 and the high oxygen concentration interface oxide region 15 becomes higher.

  Further, when the high oxygen concentration interface oxidized region 15 is formed, an oxidized region 16 is simultaneously formed on the surface of the nitride layer 13 by the heat treatment in the oxidizing gas atmosphere. Although not shown here, the oxide region 16 on the nitride layer 13 may be nitrided after the high oxygen concentration interface oxidized region 15 is formed in order to increase the dielectric constant of the gate insulating film. Nitriding can be performed by heat treatment in a nitriding gas atmosphere or irradiation with plasma containing nitrogen.

  In the case of heat treatment in a nitriding gas atmosphere, for example, in a pressure range of about 0.1 Torr to about 760 Torr, a flow rate-controlled nitriding gas atmosphere at a temperature of about 500 ° C. to about 1000 ° C. for about 1 second to about 600 seconds. Heat treatment is performed. As the nitriding gas, a gas containing nitrogen such as ammonia gas, nitrogen monoxide gas, dinitrogen monoxide gas, nitrogen dioxide gas, or a mixed gas containing two or more of such gases can be used.

  When nitriding is performed by irradiation with plasma containing nitrogen, plasma containing nitrogen, such as nitrogen plasma, ammonia plasma, or nitrogen monoxide plasma, is used. For example, the power is about 100 W to about 2000 W, and the gas pressure is about 1 mTorr to 1 Torr. The conditions are set so that the oxidized region 16 can be selectively nitrided.

  Through the steps so far, the gate insulating film composed of the high oxygen concentration interface oxide region 15, the nitride layer 13, and the oxide region 16 (or nitride region) is formed on the channel impurity diffusion region 12 of the silicon substrate 10. It becomes like this.

FIG. 9 is a schematic cross-sectional view of the relevant part in the polycrystalline silicon deposition step.
After the formation of the gate insulating film, polycrystalline silicon 17 to be a gate electrode is deposited on the entire surface using, for example, chemical vapor deposition.

FIG. 10 is a schematic sectional view showing an important part of a gate electrode processing step.
After the polycrystalline silicon 17 is formed, the polycrystalline silicon 17 is processed using a lithography technique using a photoresist 18 and a chemical reaction etching technique to form a gate electrode 19 having a predetermined shape.

FIG. 11 is a schematic sectional view of an essential part of a MOSFET.
After the formation of the gate electrode 19, first, ion implantation of an impurity of a predetermined conductivity type is performed using the gate electrode 19 as a mask using the ion implantation method to form the source / drain / extension region 20. Next, sidewall spacers 21 are formed on the side walls of the gate electrode 19, and ions of a predetermined conductivity type are ion-implanted using the gate electrodes 19 and the sidewall spacers 21 as masks to form source / drain diffusion regions 22. Finally, silicide 23, for example, cobalt silicide or nickel silicide is formed on the surface of the gate electrode 19 and the surface of the source / drain diffusion region 22 to complete the basic structure of the MOSFET. Thereafter, an interlayer insulating film, wiring, etc. may be formed according to a conventional method.

  As described above, here, in order to form a gate insulating film containing nitrogen, after forming a nitride layer on the silicon substrate, first, an oxidizing solution treatment is performed to reduce the gap between the nitride layer and the silicon substrate. An oxygen concentration interface oxidation region was formed, and then heat treatment was performed in an oxidizing gas atmosphere to supply oxygen to the low oxygen concentration interface oxidation region, thereby forming a high oxygen concentration interface oxidation region. As a result, a gate insulating film having a high average nitrogen concentration but a low nitrogen concentration and a high oxygen concentration can be formed at the interface with the silicon substrate. Therefore, by applying such a gate insulating film to a MOSFET, it becomes possible to improve device performance and its reliability, and a high-performance MOSFET can be realized.

The formation conditions of each layer and each region are examples, and are not limited to the above conditions, and can be changed according to the required characteristics of the MOSFET to be formed.
In the above description, a MOS structure or MOSFET using a silicon substrate has been described as an example. However, an SOI (Silicon On Insulator) that can form a transistor structure using a thin semiconductor layer portion in addition to a silicon substrate. It is also possible to use another substrate (semiconductor substrate) such as a substrate.

(Supplementary Note 1) In the method of manufacturing a semiconductor device,
Forming a nitride layer on the semiconductor substrate;
Forming an oxidized region between the nitride layer and the semiconductor substrate using an oxidizing solution;
Performing a heat treatment in an oxidizing gas atmosphere to increase the oxygen concentration in the oxidized region;
A method for manufacturing a semiconductor device, comprising:

(Additional remark 2) The said nitride layer consists of nitride or oxynitride, The manufacturing method of the semiconductor device of Additional remark 1 characterized by the above-mentioned.
(Supplementary Note 3) In the step of forming the nitride layer on the semiconductor substrate,
The method of manufacturing a semiconductor device according to claim 1, wherein the nitride layer is formed on the semiconductor substrate by heat-treating the semiconductor substrate in a nitriding gas atmosphere.

(Supplementary Note 4) In the step of forming the nitride layer on the semiconductor substrate,
2. The method of manufacturing a semiconductor device according to claim 1, wherein the nitride layer is formed on the semiconductor substrate by irradiating the semiconductor substrate with plasma containing nitrogen.

(Supplementary Note 5) In the step of forming the oxidized region between the nitride layer and the semiconductor substrate using the oxidizing solution,
A solution containing one or more of hydrogen peroxide, hydrochloric acid, sulfuric acid, and nitric acid is used as the oxidizing solution, and the oxidized region is formed between the nitride layer and the semiconductor substrate. The manufacturing method of the semiconductor device of Additional remark 1.

(Appendix 6) In the step of increasing the oxygen concentration in the oxidized region by performing a heat treatment in the oxidizing gas atmosphere,
The heat treatment is performed in the oxidizing gas atmosphere so that the oxygen concentration in the vicinity of the interface between the oxidized region and the semiconductor substrate is higher than the nitrogen concentration by increasing the oxygen concentration in the oxidized region. A method for manufacturing a semiconductor device.

(Appendix 7) In the step of increasing the oxygen concentration in the oxidized region by performing a heat treatment in the oxidizing gas atmosphere,
A gas containing one or more of nitrogen monoxide, dinitrogen monoxide, nitrogen dioxide, and oxygen is used as the oxidizing gas, and a heat treatment is performed in the oxidizing gas atmosphere to reduce the oxygen concentration in the oxidized region. The method of manufacturing a semiconductor device according to appendix 1, wherein the method is increased.

(Supplementary Note 8) In the step of increasing the oxygen concentration in the oxidized region by performing a heat treatment in the oxidizing gas atmosphere,
2. The method of manufacturing a semiconductor device according to claim 1, wherein the oxygen concentration in the oxidation region is increased and the nitrogen concentration in the oxidation region and the nitride layer is increased.

(Additional remark 9) After the process which heat-processes in the said oxidizing gas atmosphere and increases the oxygen concentration of the said oxidation area | region,
2. The method of manufacturing a semiconductor device according to claim 1, further comprising a step of nitriding another oxidized region formed simultaneously on the surface of the nitride layer when increasing the oxygen concentration of the oxidized region.

(Supplementary Note 10) In the step of nitriding the other oxidized region,
The method of manufacturing a semiconductor device according to appendix 9, wherein the other oxidized region is nitrided by heat-treating the other oxidized region in a nitriding gas atmosphere.

(Supplementary Note 11) In the step of nitriding the other oxidized region,
10. The method of manufacturing a semiconductor device according to appendix 9, wherein the other oxidized region is nitrided by irradiating the other oxidized region with plasma containing nitrogen.

It is a figure which shows the formation flow of a gate insulating film. It is a principal part cross-sectional schematic diagram of a silicon nitride film formation process. It is a principal part cross-sectional schematic diagram of a 1st oxidation process. It is a principal part cross-sectional schematic diagram of a 2nd oxidation process. It is a principal part cross-sectional schematic diagram of an element isolation region and a channel impurity diffusion region formation process. It is a principal part cross-sectional schematic diagram of a nitride layer formation process. It is a principal part cross-sectional schematic diagram of a low oxygen concentration interface oxidation area | region formation process. It is a principal part cross-sectional schematic diagram of a high oxygen concentration interface oxidation area | region formation process. It is a principal part cross-sectional schematic diagram of a polycrystalline-silicon deposition process. It is a principal part cross-sectional schematic diagram of a gate electrode processing process. It is a principal part cross-sectional schematic diagram of MOSFET.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 Silicon substrate 2,13 Nitride layer 3,14 Low oxygen concentration interface oxidation region 4,15 High oxygen concentration interface oxidation region 11 Element isolation region 12 Channel impurity diffusion region 16 Oxidation region 17 Polycrystalline silicon 18 Photoresist 19 Gate electrode 20 Source / drain extension region 21 Side wall spacer 22 Source / drain diffusion region 23 Silicide

Claims (5)

In a method for manufacturing a semiconductor device,
Forming a nitride layer on the semiconductor substrate;
Forming an oxidized region between the nitride layer and the semiconductor substrate using an oxidizing solution;
Performing a heat treatment in an oxidizing gas atmosphere to increase the oxygen concentration in the oxidized region;
A method for manufacturing a semiconductor device, comprising:   2. The method of manufacturing a semiconductor device according to claim 1, wherein the nitride layer is made of nitride or oxynitride. In the step of forming the oxidized region between the nitride layer and the semiconductor substrate using the oxidizing solution,
A solution containing one or more of hydrogen peroxide, hydrochloric acid, sulfuric acid, and nitric acid is used as the oxidizing solution, and the oxidized region is formed between the nitride layer and the semiconductor substrate. A method for manufacturing a semiconductor device according to claim 1. In the step of increasing the oxygen concentration in the oxidized region by performing a heat treatment in the oxidizing gas atmosphere,
The heat treatment is performed in the oxidizing gas atmosphere so that the oxygen concentration in the vicinity of the interface between the oxidized region and the semiconductor substrate becomes higher than the nitrogen concentration by increasing the oxygen concentration in the oxidized region. Semiconductor device manufacturing method. After the step of increasing the oxygen concentration in the oxidized region by performing a heat treatment in the oxidizing gas atmosphere,
2. The method of manufacturing a semiconductor device according to claim 1, further comprising a step of nitriding another oxidized region simultaneously formed on the surface of the nitride layer when increasing the oxygen concentration of the oxidized region.

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