JP2008066317A - Method for forming insulation film, apparatus for forming insulation film, method for manufacturing semiconductor device, semiconductor device, and surface treatment method for silicon carbide substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treatment method as pre-treatment for effectively forming a chemical oxide film at a low temperature when forming an insulation film that can be applied to a semiconductor device using silicon carbide (SiC) or the like. <P>SOLUTION: After heating the surface of a substrate 10 in a hydrogen-containing atmosphere, the surface is immersed into an oxidizing solution 22, or the solution 22 is sprayed over the surface, or the surface is exposed to the vapor of the solution 22. Consequently, the reactivity of the surface of the substrate 10 which is in contact with the oxidizing solution 22 is improved, and an insulation film which exhibits high performance even if formed thin is formed on the surface of the substrate 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for forming an insulating film on a surface of a base material, more specifically, selected from the group of silicon carbide, silicon, and polysilicon, a method for forming the insulating film on the surface of the base material, and a method for manufacturing a semiconductor device including the insulating film. The present invention relates to a method, a semiconductor device thereof, and a surface treatment method of a substrate of silicon carbide.

In semiconductor devices, particularly MOS-structured semiconductor devices (diodes and transistors), it is important to improve the performance of insulating films used for miniaturization of circuit elements accompanying higher integration and higher density. For example, in the case of a semiconductor device configured using a silicon substrate, particularly a MOS transistor or a MOS capacitor, a so-called high temperature thermal oxidation method is used to form an insulating film such as a gate insulating film or a capacitive insulating film. In this method, the silicon substrate is heated at a high temperature of 800 ° C. or higher in an oxidizing gas such as dry oxygen (dry) or water vapor (wet), so that the silicon dioxide (SiO ₂ ) film is formed on the surface of the silicon substrate. It is formed. However, in this case, since the initial growth rate of the silicon dioxide film is fast and it is extremely difficult to control the film thickness during this period, for example, a high performance ultrathin SiO ₂ film having a film thickness of several nanometers (nm) or less is formed with good control. There are considerable difficulties. Further, in the high-temperature thermal oxidation method, dopant diffusion in the silicon substrate occurs, and when a thick film is formed by long-time heat treatment, consideration must be given to fluctuation and destruction of shallow junctions.

On the other hand, when the substrate is silicon carbide (SiC), when forming the gate insulating film of the MOS transistor, a high temperature thermal oxidation method in a wet or dry oxidizing gas at 1100 ° C. to 1200 ° C. is adopted, A silicon dioxide film of several tens of nanometers (nm) is formed. However, this film formation requires not only a long time, but also the quality of the silicon dioxide film itself is insufficient in terms of performance compared with the case of the SiO ₂ film formed by the high temperature thermal oxidation method of silicon (Si). is there. In addition, the necessity of high-temperature treatment greatly hinders industrialization due to an increase in necessary equipment costs and a restriction on the degree of freedom of design for other processes or materials used. Therefore, especially when the substrate is silicon carbide, many problems still remain in improving the performance and industrialization of so-called MOS devices.

  Furthermore, in the case where the substrate is silicon carbide, in addition to the above-mentioned problems, there is a problem that deep irregularities exist on the surface of the substrate, and because the carbon remains in the formed insulating film, the fixed charge density and interface state density are low. There is a problem that it is expensive. Therefore, technical barriers for industrial use of a film formed by high-temperature thermal oxidation as a gate insulating film for a semiconductor device having a MOS structure on silicon carbide are very high. Is strongly demanded.

As an insulating film forming method other than the high temperature thermal oxidation method, for example, chemical vapor deposition (CVD), in which a SiO ₂ film is deposited on the surface of a silicon substrate by thermally decomposing monosilane or the like under conditions of several hundred degrees Celsius, There are a method of depositing a SiO ₂ film in plasma (PCVD), and various physical vapor deposition methods (PVD) such as sputtering and vapor deposition. However, these vapor deposition methods also do not sufficiently satisfy the requirements as gate insulating films of MOS transistors.

On the other hand, the present inventor has already developed a chemical oxidation technique that forms a SiO ₂ film on the surface of a semiconductor substrate by bringing an oxidizing solution or gas into contact with the semiconductor substrate containing silicon. (For example, refer to Patent Document 1).

In general, as an insulating film applied to a semiconductor device, a silicon dioxide film formed on a silicon substrate by a high-temperature thermal oxidation method is stable in performance, which is desirable in terms of characteristics of the semiconductor device. However, from the viewpoint of the stability of various shapes on the semiconductor surface and the maintenance of the process, the industry has a great expectation for forming an insulating film under low temperature conditions as in the above-described chemical oxidation technique.
Japanese Patent Laying-Open No. 2005-313102 (Publication date: November 4, 2005) Japanese Patent Laying-Open No. 2005-3131003 (Publication date: November 4, 2005) Japanese Patent Laying-Open No. 2005-313152 (Publication date: November 4, 2005) JP 2002-289612 A (publication date: October 4, 2002) Nagayama and 2 others, "Low-temperature formation and spectroscopic observation of SiO2 / Si structure by chemical method", Abstracts of lectures of the Physical Society of Japan, The Physical Society of Japan, August 15, 2003, Vol. 58, No. 2, p. 771

  The object of the present invention is not particularly limited to the following points, but one object is, for example, cubic silicon carbide (3C-SiC, hereinafter simply referred to as SiC or silicon carbide). A high-performance oxide film is formed at a low temperature using a chemical method even on a substrate having a large surface irregularity or a high interface state density, and is used industrially. Specifically, an insulating film forming method for chemically forming an insulating film on a substrate surface using an oxidizing solution, a mist solution, or a gas thereof, an apparatus for forming the insulating film, or an insulating film A semiconductor device including a film and a method for manufacturing the semiconductor device are provided.

  Another object of the present invention is to form a silicon dioxide film as a chemical oxide film developed as an oxidation method at a low temperature even more stably and reliably for a substrate selected from silicon carbide, silicon, and polysilicon. It is an object of the present invention to provide a method for forming an insulating film on a substrate surface, a device for forming the insulating film, a semiconductor device including the insulating film, and a method for manufacturing the semiconductor device.

  Another object of the present invention is to provide an effect of forming an oxide film by the above-described chemical method even on a substrate having poor substrate surface flatness such as a silicon carbide substrate and a high interface state density. It is an object of the present invention to provide a surface treatment method as a pretreatment.

  By carrying out the present invention, the flatness of the substrate surface at the atomic layer level after the formation of the insulating film, which has been considered difficult until now, or the reduction of fixed charge and interface state density is achieved. An ultra-thin high-performance insulating film can be formed.

  The present invention does not impose any strict limitation on the target base material, but an extremely thin insulating film that can be used for MOS transistors using silicon carbide, etc. If this formation is realized by a low temperature process, it can be said that it will greatly contribute to the development of the semiconductor industry and the like. The inventor has intensively studied to further improve the performance of an insulating film obtained by a method of forming an insulating film using a chemical method and a semiconductor device using the insulating film. As a result of the research, the inventor has found that an unprecedented high-performance insulating film can be formed on the surface of a substrate by adopting a new processing method and manufacturing method that change the conventional idea. The inventor has also found that a semiconductor device having excellent electrical characteristics can be obtained by the insulating film.

  That is, in the method for forming an insulating film on one substrate surface of the present invention, after heating at least the substrate surface in an atmosphere containing hydrogen, the substrate surface is immersed in an oxidizing solution, or the solution is Spraying or exposing to the vapor of the solution.

  As a result, as described above, a high-performance insulating film that can be applied to a semiconductor device can be obtained by improving the flatness of the substrate surface or reducing the interface state density.

  In addition, a method for manufacturing a semiconductor device according to the present invention includes a step of forming an insulating film by any one of the methods described above.

  By using this manufacturing method, a semiconductor device having excellent electrical characteristics can be manufactured even if the surface of the base material is physically rough or a base material (for example, a semiconductor substrate) having a high interface state density. .

  One semiconductor device according to the present invention includes an insulating film formed by any one of the methods described above.

  If this insulating film is formed, the flatness of the substrate surface is improved or the interface state density is reduced, so even if the initial flatness of the substrate surface is poor or the interface state is low. Even with a high-density base material (for example, a semiconductor substrate), a semiconductor device having excellent electrical characteristics can be obtained.

  Also, one insulating film forming apparatus of the present invention comprises a means for heating at least the substrate surface in an atmosphere containing hydrogen, and then immersing the substrate surface in an oxidizing solution or spraying the solution. Or a means for exposure to the vapor.

  As a result, the flatness of the substrate surface is improved or the interface state density is reduced. For example, when a semiconductor device having a MOS structure is subsequently manufactured, the semiconductor device has excellent electrical characteristics.

  In addition, the silicon carbide substrate surface treatment method of the present invention includes a step of heating at 200 ° C. to 500 ° C. in an atmosphere containing hydrogen.

  This encourages the introduction of hydrogen into the silicon carbide surface layer. Further, hydrogen once taken into the silicon carbide surface layer is released only to the extent that the effects of the present invention are not impaired even by heat treatment. As a result, when an insulating film is subsequently formed by a chemical oxidation method, the speed of forming the insulating film on the silicon carbide surface is improved. Further, when a MOS structure is manufactured thereafter, for example, a semiconductor device with very little leakage current can be obtained.

  According to the present invention, it is possible to improve the flatness of the substrate surface at the atomic layer level after the formation of the insulating film or reduce the interface state density of the substrate surface layer and form a high-performance insulating film. it can. Further, by manufacturing a semiconductor device using the insulating film obtained according to the present invention, a semiconductor device having excellent electrical characteristics can be obtained. In addition, if the present invention is applied to a silicon carbide substrate, an insulating film is formed by a chemical oxidation method after that, so that the insulating film formation rate on the surface of the silicon carbide is about 1.6 times that of the conventional case. Will be increased. Further, when a MOS structure is manufactured thereafter, the leakage current is sufficiently reduced to such an extent that it can be practically used as a MOS transistor, so that a high-performance semiconductor device can be obtained.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this description, common parts are denoted by common reference symbols throughout the drawings.
<First Embodiment>
1A and 1B are explanatory views of the insulating film forming apparatus of the present embodiment. In this embodiment, 3C—SiC (cubic silicon carbide) is used as a base material (hereinafter referred to as a substrate or a silicon carbide substrate for convenience). Further, this silicon carbide substrate was an n-type substrate having a surface orientation (100) and a surface resistivity of 0.02 to 0.03 Ω · cm, in which an epitaxial growth layer having a thickness of 6 μm was formed on the substrate. .

  First, the substrate 10 is processed for 20 minutes in a processing chamber in a hydrogen atmosphere heated to 400 ° C. using a processing apparatus 100 as shown in FIG. 1A. Specifically, by introducing hydrogen from the hydrogen cylinder into the processing chamber 14 while heating the processing chamber 14 with the heater 16, the substrate 10 supported by the support 12 in the processing chamber 14 is heat-treated. The The processing conditions in the chamber at this time were 100% hydrogen at normal pressure.

  Here, the hydrogen concentration is preferably 75 vol% or more, and more preferably 80 vol% or more. For example, the operation based on the present invention can be achieved in a processing time of about 10 to 60 minutes by appropriately selecting a processing temperature in a gas atmosphere in the processing chamber 14 at a normal pressure and a hydrogen concentration of 80 vol% or more. . In this case, an inert gas such as nitrogen shown in FIG. 1A can be included as a gas other than hydrogen. In addition, although it is thought that even if it is less than 50 vol%, the effect of this invention is not lost completely, it is so preferable that hydrogen concentration is high. However, if hydrogen is used in a certain range of concentrations, there is a risk of explosion and its handling is very difficult. Therefore, the use concentration may be limited for the purpose of avoiding such danger.

  The heating temperature is preferably 200 ° C. or higher and 500 ° C. or lower. Even if it is outside the above temperature range, it is considered that the effect of the present invention is not completely lost, but if it is less than 200 ° C., hydrogen may not be sufficiently supplied to the substrate surface layer, This is because if the temperature exceeds 600 ° C., the hydrogen once taken into the substrate surface layer is likely to be released due to the high temperature. From these viewpoints, a more preferable heating temperature range is 250 ° C. or more and 550 ° C. or less, and most preferably 250 ° C. or more and 500 ° C. or less.

  Table 1 shows the result of comparing the surface roughness of the substrate with and without the heat treatment in the hydrogen atmosphere. The surface roughness was measured using an AFM (atomic force microscope).

  As shown in Table 1, by performing the processing of the present embodiment, about 60% of the substrate surface roughness before processing was reduced in the mean square roughness. Despite the low-temperature treatment method as in this embodiment, a silicon carbide substrate having an extremely smooth surface at the atomic layer level with a root mean square roughness of 0.5 nm or less on the substrate surface could be obtained.

  Next, using the processing apparatus 200 as shown in FIG. 1B, the substrate subjected to the above-described processing is immersed in an oxidizing solution. Specifically, the substrate 10 held by a known substrate holding tool (not shown) for convenience is immersed in concentrated nitric acid (aqueous solution) 22 having a concentration of 40 wt% at room temperature (about 25 ° C.) filled in the treatment tank 24. The In this state, the substrate 10 is heated to a state in which the concentrated nitric acid (aqueous solution) 22 is in a boiling state by a heater 26 (for example, an acid-resistant quartz heater for liquid heating). If this state is continued, it finally reaches azeotropic nitric acid (azeotropic nitric acid) having a boiling point of 120.7 ° C. and a nitric acid concentration of 68 wt%. As a result, the nitric acid concentration and boiling point are maintained even if heating is continued as it is. As a result of maintaining this state for about 7 hours, as shown in FIG. 2A, the structure 500 including the film 51 having a uniform thickness was formed on the substrate 10.

  Here, the concentration of the initial concentrated nitric acid (aqueous solution) is not particularly limited, and the effects of the present invention can be achieved even if the concentration is other than 40 wt% (for example, 20 wt% or 60 wt%). Further, the temperature of the solution in the immersion treatment in the oxidizing solution (here, concentrated nitric acid) may not reach the boiling state completely. That is, since the nitric acid concentration is sequentially increased by heating the oxidizing solution, it is not always necessary to heat to the boiling point. The effect of the present invention is substantially achieved even near the boiling point (for example, a temperature lower by about 1 to 5 ° C. than the boiling point).

  Furthermore, instead of a solution with a continuous increase in concentration as in the present embodiment, at least one predetermined concentration (for example, 40 wt% or 60 wt%) heated near or at the boiling point is used as a substrate immersion solution. At least two kinds of solutions of concentrated nitric acid (aqueous solution) and nitric acid in a substantially azeotropic state or azeotropic state may be prepared in advance, and in this case, the same effect as that of the present embodiment is exhibited. Here, being near the boiling point is a temperature lower by about 1 to 5 ° C. than the boiling point, and the substantially azeotropic state is a temperature lower by about 1 to 5 ° C. than the temperature in the azeotropic state.

  Further, when a film is formed in multiple stages by preparing two or more kinds of solutions as described above, in the initial stage process (if it is a two-stage process, the process in the first stage) is not necessarily oxidizing. It is not necessary to heat the solution from the beginning to near the boiling point or to the boiling point. For example, as the first stage, the substrate 10 after being subjected to the heat treatment in the atmosphere containing hydrogen described above is sequentially heated in a state of being immersed in concentrated nitric acid (aqueous solution) having a concentration of 40 wt% at room temperature so as to be close to or near the boiling point. By raising the temperature to 0.1 nm, an extremely thin film having a thickness of 0.1 nm to 1 nm is formed. Thereafter, as a second stage, the substrate 10 may be immersed in a higher concentration of substantially azeotropic nitric acid or azeotropic nitric acid to form a film continuously to a desired thickness. Even in such a case, an effect similar to the effect of the present invention is exhibited.

  Further, when a natural oxide film is formed on the surface of the substrate 10 before performing the heat treatment in the hydrogen atmosphere described above, for example, it is immersed in a dilute hydrofluoric acid solution having a concentration of 0.8 vol% for about 5 minutes, Further, the natural oxide film is completely removed by rinsing (cleaning) with ultrapure water for 5 minutes.

  FIG. 3 is a cross-sectional view (photograph) obtained by TEM analysis. It can be seen that the interface between the surface of the substrate 10 and the film 51 formed by the above-described processing is extremely smooth. It can be seen from this cross-sectional view that the thickness t of the film in this embodiment is about 21 nm.

Next, when the film formed on the above-mentioned silicon carbide substrate was measured with an X-ray photoelectron spectrum (XPS) measuring device, the characteristic diagram of FIG. 4A was obtained. From this result, it was found that the composition of this film was a film mainly composed of silicon dioxide (SiO ₂ ).

  FIG. 4B is an enlarged view of the binding energy region in the vicinity of the 2p orbit of Si in the same XPS measurement apparatus. Here, for comparison, a film formed on the surface of the base material when the above-described heat treatment in a hydrogen atmosphere is not performed and the other processing conditions are the same is also shown. Specifically, (a) is a measurement result of a film (comparative example) that was not subjected to the above-described heat treatment in a hydrogen atmosphere, and (b) is a film formed in the present embodiment.

  As shown in this figure, a peak in the vicinity of 101 eV indicating the Si—C bond was not observed in the film (b) formed according to this embodiment, but was observed only in the film (a) of the comparative example. This indicates that the film (b) is thicker than the film (a). Here, the film thickness of the film (a) was found to be about 13 nm from the area intensity ratio between the peak of the Si—C bond and the peak near 104 eV indicating the Si—O bond. Therefore, compared with the result of FIG. 3, the film formation rate of the film formed according to the present embodiment is 1.6 times or more compared with the case where the heat treatment is not performed in the hydrogen atmosphere. This is because hydrogen penetrates into the inside of the substrate and weakens its bond, and also promotes the oxidizing power of nitric acid to act strongly on Si on the surface of the substrate, or the activity of Si on the surface of the substrate in contact with the nitric acid solution This is thought to be due to the fact that the oxidation reaction is promoted. Although the detailed mechanism has not yet been elucidated, it goes without saying that the technical effect of significantly increasing the film formation rate disclosed in this embodiment is a significant advance in the sense of industrializing the above-described processing.

<Second Embodiment>
Electrode metal films (metal-containing films) 62 and 63 were formed on both surfaces of the structure 500 formed by the method according to the first embodiment. Thereafter, the metal film 62 on the side on which the insulating film 51 is formed is patterned into a desired electrode shape (circular with a diameter of 3 mm) by a known photolithography process to obtain a MOS capacitor as shown in FIG. 2B. 600 was produced. This metal film is formed by depositing an Al alloy for electrodes (aluminum (Al) alloy containing about 1% by weight of silicon (Si)) to a film thickness of about 200 nm by a well-known resistance heat treatment vapor deposition method. (Hereinafter, this type of metal film electrode is simply referred to as an Al electrode). Here, the metal film for the electrode is not limited to the Al electrode, and may be another metal. Further, a polysilicon electrode can be used instead of the electrode made of the metal film.

  FIG. 5 is a CV characteristic diagram showing the relationship between the capacitance (C) of the MOS capacitor of this embodiment and the applied voltage (V). As can be seen from this characteristic diagram, a sufficient capacitor capacity (capacitance) was obtained. In addition, from this characteristic diagram, it is understood that no property due to the presence of the interface state is observed, and a good CV characteristic is achieved.

The film thickness calculated from the CV characteristics was found to be 21.3 nm when the film composition was typical silicon dioxide (SiO ₂ ). This agrees well with the measurement result based on the cross-sectional view (photograph) in the TEM analysis of FIG.

  FIG. 6 is a relationship between the current (I) and the applied voltage (V), that is, an IV characteristic diagram of the MOS capacitor manufactured in this embodiment. As can be seen from this characteristic diagram, the dielectric breakdown voltage is about 25 V, and from this point of view, the high insulating property of the film (film mainly composed of silicon dioxide) formed according to the present embodiment was confirmed.

  Further, FIG. 7 shows an IV characteristic diagram regarding the voltage dependence of the leakage current value. Here, a characteristic diagram of the MOS capacitor (comparative example) manufactured without performing the heat treatment in the atmosphere containing hydrogen shown in the previous embodiment is shown in (a), and the characteristic of the MOS capacitor manufactured in this embodiment is shown in FIG. The characteristic diagram is shown in (b). As is apparent from this figure, it can be seen that the leakage current value was significantly reduced by performing the heat treatment in an atmosphere containing hydrogen. This significant reduction in leakage current proves that even a substrate with high interface state density such as silicon carbide or poor flatness can function satisfactorily as a semiconductor device with an extremely thin film. . In particular, when the present invention is applied to a MOS type transistor using silicon carbide, it can be used as an insulating film used for a high-frequency transistor.

  Although the embodiments of the present invention have been specifically described so far, the above-described embodiments are merely examples for carrying out the present invention. For example, in order to achieve the effects of the present invention, it is not always necessary to immerse the target substrate surface in an oxidizing solution. Specifically, using a processing apparatus 300 as shown in FIG. 1C, the substrate 10 and the oxidizing solution 22 are placed in a predetermined container 34, and the container 34 is heated by a heater 36 to evaporate the oxidizing solution 22. May be. Thereby, since the board | substrate 10 is exposed to the vapor | steam 32, an effect is show | played like the previous embodiment. At this time, fresh steam 32 can be always exposed to the substrate 10 by appropriately exhausting from the exhaust pump. In addition, using a processing apparatus 400 as shown in FIG. 1D, an oxidizing solution mist 42 may be sprayed to the substrate 10 contained in a predetermined container 44 by the sprayer 46. In this case, the mist 42 may be a vapor of an oxidizing solution. For example, even if the mist 42 is about room temperature and does not reach the boiling point of the oxidizing solution, the mist 42 can be sprayed in the form of a mist. It is effective for.

  In the above-described embodiment, high concentration nitric acid having a concentration of 40 wt% is used. Instead, perchloric acid, sulfuric acid, ozone-dissolved water, hydrogen peroxide solution, and a mixed solution of hydrochloric acid and hydrogen peroxide solution are used. A mixed solution of sulfuric acid and hydrogen peroxide solution, a mixed solution of ammonia water and hydrogen peroxide solution, a mixed solution of sulfuric acid and nitric acid, and a solution having at least one oxidizing property selected from the group of aqua regia, or You may use the mist (mist) of the solution, or the vapor | steam. Even with these solutions, the same effects as those of the present invention can be obtained.

  In the above-described embodiment, boiling nitric acid having a nitric acid concentration of 68 wt% (so-called azeotropic nitric acid) is used. Instead, a solution of azeotropic perchloric acid or a mist (mist) of the solution is used. ) Or its vapor. In addition, when the azeotropic state is maintained using an azeotropic mixture of water and strong acid as the high-concentration oxidizing solution, the concentrations of the solution and the vapor become constant. Therefore, the use of an azeotropic mixture is preferable in that the thickness of the film formed on the substrate depends on the processing time, so that the film thickness can be controlled by time management.

  In the above embodiment, 3C-SiC (cubic silicon carbide) is used as the base material. However, the present invention uses hexagonal silicon carbide (4H-SiC or 6H-SiC) as the base material. In the case of such a case, the same effect as that of the present invention can be obtained. Furthermore, according to the present invention, a group selected from the group consisting of silicon carbide, silicon and polysilicon other than the above-described 3C-SiC (cubic silicon carbide) and hexagonal silicon carbide (4H-SiC or 6H-SiC). Also on the material, an insulating film having the same effect as at least a part of the effect of the present invention is formed.

  In addition, since the present invention enables formation of a high-performance insulating film by low-temperature treatment, the base material on which the insulating film is formed includes a semiconductor film formed on the surface of the resin substrate. For example, the present invention can be applied to a so-called flexible substrate. Accordingly, all modifications that come within the spirit and scope of the present invention are intended to be included within the scope of the following claims.

It is the heat processing apparatus in hydrogen containing atmosphere among the insulating film formation apparatuses in one embodiment of this invention. It is the immersion treatment apparatus by an oxidizing solution among the insulating film formation apparatuses in one embodiment of the present invention. It is the exposure apparatus by the vapor | steam of oxidizing solution among the insulating film formation apparatuses in other embodiment of this invention. It is the exposure apparatus by the vapor | steam or mist of an oxidizing solution among the insulating film formation apparatuses in other embodiment of this invention. It is sectional drawing explaining the structure of the structure manufactured by one Embodiment of this invention. It is sectional drawing explaining the structure of the semiconductor device (MOS capacitor) manufactured by other embodiment of this invention. It is a TEM analysis sectional view of an insulating film formed in one embodiment of the present invention. It is a characteristic view by the X-ray photoelectron spectrum (XPS) measurement of the insulating film formed in one embodiment of this invention. It is a characteristic view by the X-ray photoelectron spectrum (XPS) measurement regarding Si2p of the insulating film formed in one Embodiment of this invention, and the comparative insulating film. It is a CV characteristic figure of the semiconductor device (MOS capacitor) manufactured by other embodiment of this invention. It is an IV characteristic figure of the semiconductor device (MOS capacitor) manufactured by other embodiment of this invention. It is an IV characteristic figure regarding the voltage dependence of the leakage current value of the semiconductor device (MOS capacitor) manufactured by other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 12 Support stand 14 Processing chamber 16, 26, 36 Heater 24 Processing tank 34, 44 Container 46 Sprayer 100, 200, 300, 400 Processing device 51 Insulating film 62, 63 Metal film 500 Structure 600 MOS capacitor

Claims (16)

After heating at least the substrate surface in an atmosphere containing hydrogen, the substrate surface is immersed in an oxidizing solution, sprayed with the solution, or exposed to the vapor of the solution. Insulating film forming method. The oxidizing solution is nitric acid, perchloric acid, sulfuric acid, ozone-dissolved water, hydrogen peroxide solution, mixed solution of hydrochloric acid and hydrogen peroxide solution, mixed solution of sulfuric acid and hydrogen peroxide solution, ammonia water and peroxidation. The method for forming an insulating film on the substrate surface according to claim 1, wherein the insulating film is at least one solution selected from the group consisting of a mixed solution of hydrogen water, a mixed solution of sulfuric acid and nitric acid, and aqua regia. The method for forming an insulating film on a substrate surface according to claim 1, wherein the heating temperature in the atmosphere is 200 ° C or higher and 600 ° C or lower, and the oxidizing solution is a nitric acid solution having a concentration of 20% or higher. The method for forming an insulating film on the substrate surface according to claim 1, wherein the hydrogen concentration is 75 vol% or more. The method for forming an insulating film on the surface of the substrate according to claim 1, wherein the substrate is selected from the group consisting of silicon carbide, silicon, and polysilicon. The method for forming an insulating film on a substrate surface according to claim 1, wherein the insulating film is mainly silicon dioxide (SiO ₂ ). The method for forming an insulating film on a substrate surface according to claim 1, wherein the oxidizing solution is hot nitric acid heated near or at the boiling point. The method for forming an insulating film on a substrate surface according to claim 1, wherein the oxidizing solution is hot nitric acid heated from room temperature to near or at the boiling point. 2. The insulation to the substrate surface according to claim 1, wherein the oxidizing solution is at least two kinds of nitric acid having a predetermined concentration near or at a boiling point and nitric acid in a substantially azeotropic or azeotropic state. Film forming method. 2. The method for forming an insulating film on a substrate surface according to claim 1, wherein the oxidizing solution is a solution heated from nitric acid having an arbitrary concentration to nitric acid in an approximately azeotropic or azeotropic state from room temperature. A method for manufacturing a semiconductor device, comprising a step of forming an insulating film by the method according to claim 1. A semiconductor device comprising an insulating film formed by the method according to claim 1. To a substrate surface having means for heating at least the surface of the substrate in an atmosphere containing hydrogen, and then means for immersing the substrate surface in an oxidizing solution, spraying the solution, or exposing the vapor to the vapor Insulating film forming apparatus. A method for treating a surface of a silicon carbide substrate, comprising a step of heating at least a surface of the silicon carbide substrate at 200 ° C. to 600 ° C. in an atmosphere containing hydrogen. The surface treatment method for a silicon carbide substrate according to claim 14, wherein the hydrogen concentration is 75 vol% or more. A silicon carbide substrate having a root mean square roughness (Rq) of 0.5 nm or less of the substrate surface formed by the method according to claim 14.

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