JP2000169246A - Silicon carbide sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a silicon carbide sintered compact having high density, containing small amounts of organic and inorganic impurities existing on the surface or in the vicinity of the surface. SOLUTION: This silicon carbide sintered compact contains <1.0×1011 atom/cm2 impurities existing on the surface or in the vicinity of the surface of the silicon carbide sintered compact and has >=2.9 g/cm2 density and <=10 ppm total content of impurity element. The silicon carbide sintered compact is obtained by a method comprising a sintering process for hot-pressing a mixture of silicon carbide powder and a nonmetallic sintering auxiliary at 2,000-2,400 deg.C under 300-700 kg/cm2 in a nonoxidizing atmosphere and a cleaning process for cleaning the silicon carbide sintered compact having passed the sintering process by a wet process.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a silicon carbide sintered body applicable to various semiconductor members and electronic components. More specifically, the present invention relates to a silicon carbide sintered body which is used for a dummy wafer, a target, a heating element, and the like and has a high density and adheres to a surface and near the surface, and has little organic substance contamination, metal element contamination, and particle contamination.

[0002]

BACKGROUND OF THE INVENTION Silicon carbide, particularly a silicon carbide sintered body, is a substance having a strong covalent bond, and makes use of its excellent properties such as high-temperature strength, heat resistance, abrasion resistance, and chemical resistance. And have been used in many applications. These advantages have attracted attention, and application to the fields of electronics, information, and semiconductors has recently been expected.

As semiconductor silicon integrated circuits become more highly integrated and thinner, the various semiconductor members and electronic components used in these fields are required to have higher purity and higher density. A hot press sintering method and a reaction sintering method using a metal-based sintering agent have been studied extensively. However, silicon carbide sintered bodies obtained by these sintering methods are:
High-purity, high-density, but pre- and post-production processes (sintering, processing, handling, etc.) have been contaminated on and near the surface.

[0004] Therefore, in order to apply the silicon carbide sintered body to various semiconductor members and electronic components, that is, to prevent contamination and particles from contaminating, it is necessary to achieve a surface purity equivalent to that of a silicon wafer by surface cleaning. Although indispensable, at present, a silicon carbide sintered body having a satisfactory surface purity has not yet been obtained.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned facts, and an object of the present invention is to provide a high-density, low-organic and inorganic impurity present on and near the surface. An object of the present invention is to provide a silicon carbide sintered body.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have obtained a high-density, high-purity sintered silicon carbide that can be applied to various semiconductor members and electronic components, but still have problems such as process contamination. The present inventors have paid attention to the fact that the organic and inorganic impurity concentrations of the surface and the oxide film layer are increased, and have reached the present invention. That is, in the present invention, <1> the amount of impurities present on the surface and near the surface of the silicon carbide sintered body is less than 1.0 × 10 ¹¹ atoms / cm ² and the density is 2.9 g / cm ² or more. It is a silicon carbide sintered body characterized by the above.

<2> The total content of impurity elements in the silicon carbide sintered body is 10 ppm or less.
1> The silicon carbide sintered body according to <1>.

<3> A mixture of silicon carbide powder and a nonmetallic sintering aid is prepared at a temperature of 2000 to 2400 ° C. and a pressure of 300
~ 700 kg / cm ² , obtained by a manufacturing method including a sintering step of hot pressing under a non-oxidizing atmosphere, and a washing step of wet-cleaning the silicon carbide sintered body after the sintering step. The silicon carbide sintered body according to <1> or <2>.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The sintered silicon carbide of the present invention
The amount of impurities present on the surface and near the surface (hereinafter referred to as surface cleanliness
There is that. ) Is 1.0 × 10¹¹atom / cm
^TwoLess than 5 × 10^Tenatom / cm
^TwoAnd more preferably 1 × 10 ^Tenatom / cm
^TwoIt is. The impurity amount is 1.0 × 10¹¹atom / cm
^TwoAbove the limit, impurities present on the surface and near the surface
Cause contamination, particles, etc.
Rub In the present invention, "existing on the surface and near the surface"
The “impurity amount” indicates the impurity amount of each impurity element,
"Impurities" are substantially Si, C, O, N, halogen
And elements other than noble gases. Also,
“Surface and near surface” refers to the surface of the silicon carbide sintered body substrate.
The surface and the natural oxide film naturally formed on the outermost surface
To taste. Note that the natural oxide film is SiO 2_TwoMembrane
Is usually about 40 to 60 nm thick (J. Sasaki)
Husband, Journal of the Ceramic Industry Association, Vol. 95, p. 84 (1987)).

The amount of impurities existing on the surface and in the vicinity of the surface is determined by ICP-MS (“Inductively Cou”).
Pled Plasma Mass Spectrom
eter (inductively coupled plasma mass spectrometer) ") or TXRF (" Total Reflection X-
Ray Fluorescence meter (total reflection X-ray fluorescence spectrometer) "). Note that the ICP-MS analysis value and the TXRF analysis value are almost equal.

[0011] The silicon carbide sintered body of the present invention has a density of 2.
9 g / cm ³ or more, preferably 3.0 g / cm ³
That is all. If the density is less than 2.9 g / cm ³ , mechanical properties such as bending strength and breaking strength and electrical properties are reduced, and particles are increased to cause particle contamination.

[0012] The silicon carbide sintered body of the present invention preferably has a total content of impurities of 10 ppm or less, more preferably 5 ppm or less. When the total content exceeds 10 ppm, impurities are easily diffused at the time of use at a high temperature, and for example, there is a possibility that a semiconductor silicon surface is contaminated, and a pn junction leak causes inversion failure. In the present invention, the total content of impurities in the silicon carbide sintered body does not include impurities on the surface and near the surface.

Hereinafter, the silicon carbide sintered body of the present invention will be described through a manufacturing method. The silicon carbide sintered body of the present invention,
It is obtained by a manufacturing method including a step of manufacturing a silicon carbide sintered body and a step of cleaning the silicon carbide sintered body.

The step of manufacturing the silicon carbide sintered body will be described in detail. In the step of producing the silicon carbide sintered body, the mixture of the silicon carbide powder and the nonmetallic sintering aid is heated at a temperature of 2%.
000-2400 ° C, pressure 300-700kg / c
m ² , a step including a sintering step of hot-pressing in a non-oxidizing atmosphere (hereinafter sometimes referred to as a sintering step).

The silicon carbide powder is obtained by homogeneously mixing a silicon source containing at least one or more liquid silicon compounds, a carbon source containing at least one or more liquid organic compounds, and a polymerization or crosslinking catalyst. Baking the solid obtained in a non-oxidizing atmosphere to produce silicon carbide powder (sometimes referred to as producing silicon carbide powder).
Is preferably obtained by

[0016] The silicon carbide sintered body of the present invention may contain nitrogen. As a method for introducing nitrogen into the silicon carbide sintered body, in the step of producing the silicon carbide powder,
A method of adding at least one or more nitrogen sources (hereinafter, sometimes referred to as nitrogen sources) together with a silicon source and a carbon source;
Alternatively, in the sintering step, a method in which a nitrogen source is added together with a nonmetallic sintering aid is used.

The substance used as the nitrogen source is preferably a substance that generates nitrogen by heating, and examples thereof include polyimide resins and precursors thereof, and various amines such as hexamethylenetetramine, ammonia, and triethylamine.

When the nitrogen source is added simultaneously with the silicon source in the process of producing the silicon carbide powder, the nitrogen source may be added in an amount of 80 μg to 100 μg per 1 g of the silicon source.
0 μg. In addition, in the sintering step, when adding together with the nonmetallic sintering aid, 1 g of the nonmetallic sintering aid is used.
200 to 2000 μg, preferably 150
0 μg to 2000 μg.

The silicon carbide powder and the process for producing the silicon carbide powder will be described. The silicon carbide powder,
Examples thereof include α-type, β-type, amorphous, and a mixture thereof. In particular, β-type silicon carbide powder is preferably used.
In the silicon carbide sintered body of the present invention, the proportion of β-type silicon carbide in the entire silicon carbide component is preferably 70% or more, more preferably 80% or more, and 100% β-type silicon carbide. It may be. Therefore, the content of the β-type silicon carbide powder in the silicon carbide powder as a raw material is preferably 60% or more, and more preferably 65% or more.

The grade of the β-type silicon carbide powder is not particularly limited, and for example, generally available β-type silicon carbide powder can be used. The particle size of the silicon carbide powder is preferably small from the viewpoint of high density, about 0.01 to 10 μm, and more preferably 0.05 to 1 μm.
It is preferably about μm. If the particle size is less than 0.01 μm, it is difficult to handle in processing steps such as measurement and mixing, and if it exceeds 10 μm, the specific surface area is small, that is, the contact area with the adjacent powder is small, and the density is increased. This is not preferable because it becomes difficult.

The silicon carbide powder preferably has a particle size of 0.05 to 1 μm, a specific surface area of 5 m ² / g or more, free carbon of 1% or less, and an oxygen content of 1% or less. Can be In addition, the particle size distribution of the silicon carbide powder used is not particularly limited, and at the time of production of the silicon carbide sintered body, from the viewpoint of improving the packing density of the powder and the reactivity of silicon carbide, two or more peaks are considered. Those having values may also be used. In order to obtain a high-purity silicon carbide sintered body, a high-purity silicon carbide powder may be used as a raw material silicon carbide powder.

The high-purity silicon carbide powder is, for example,
A silicon source containing at least one or more liquid silicon compounds, a carbon source containing at least one or more liquid organic compounds that generate carbon by heating, a polymerization or crosslinking catalyst, and optionally a nitrogen source are homogeneously mixed. It is preferable to obtain a solid material obtained by mixing in a non-oxidizing atmosphere and then baking it in a non-oxidizing atmosphere by a manufacturing method including a firing step (hereinafter sometimes referred to as a step of manufacturing silicon carbide powder).

A silicon source containing the silicon compound (hereinafter referred to as a silicon source)
Sometimes referred to as a silicon source. As), a liquid and a solid can be used in combination, but at least one of them must be selected from liquid. As the liquid, a polymer of alkoxysilane (mono-, di-, tri-, tetra-) and tetraalkoxysilane is used. Among alkoxysilanes, tetraalkoxysilane is suitably used, and specific examples thereof include methoxysilane, ethoxysilane, propoxysilane, butoxysilane and the like, and ethoxysilane is preferred from the viewpoint of handling. Examples of the tetraalkoxysilane polymer include a low molecular weight polymer (oligomer) having a degree of polymerization of about 2 to 15 and a liquid silicate polymer having a higher degree of polymerization. Examples of solid materials that can be used in combination with these include silicon oxide. In the present invention, silicon oxide means, in addition to SiO, silica sol (colloidal ultrafine silica-containing liquid, containing an OH group or an alkoxyl group therein), silicon dioxide (silica gel, fine silica,
(Quartz powder) and the like.

Among the above-mentioned silicon sources, from the viewpoint of good homogeneity and handling properties, tetraethoxysilane oligomers and mixtures of tetraethoxysilane oligomers with fine powder silica are preferred. In addition, a high-purity substance is used for these silicon sources, and the initial impurity content is preferably 20 ppm or less, more preferably 5 ppm or less.

As the carbon source containing an organic compound which generates carbon by heating (hereinafter, sometimes referred to as a carbon source), in addition to a liquid source, a liquid source and a solid source can be used in combination. Organic compounds that have a high residual carbon ratio and are polymerized or cross-linked by catalyst or heating, specifically, for example, phenolic resins, furan resins, polyimides, polyurethanes, resin monomers and prepolymers such as polyvinyl alcohol are preferable, and cellulose. Liquid substances such as sucrose, pitch, tar and the like are also used, and a resol type phenol resin is particularly preferable. The purity can be controlled and selected as appropriate depending on the purpose. In particular, when high-purity silicon carbide powder is required, it is desirable to use an organic compound containing no metal at 5 ppm or more.

In the production of the high-purity silicon carbide powder, the ratio of carbon to silicon (hereinafter abbreviated as C / Si ratio) is
It is defined by elemental analysis of a carbide intermediate obtained by carbonizing the mixture at 1000 ° C. Stoichiometrically, when the C / Si ratio is 3.0, the free carbon in the generated silicon carbide should be 0%, but actually, the low C / Si ratio is caused by the volatilization of the simultaneously generated SiO gas. , Free carbon is generated. It is important to determine the blending in advance so that the amount of free carbon in the produced silicon carbide powder does not become an amount unsuitable for production use such as a sintered body. Normally, when sintering at 1600 ° C. or more near 1 atm, the C / Si ratio is 2.0
When it is set to 2.5, free carbon can be suppressed, and this range can be suitably used. C / Si ratio of 2.5
With the above, free carbon is significantly increased, but since this free carbon has an effect of suppressing grain growth, it may be appropriately selected according to the purpose of forming particles. However, when firing at a low or high pressure in the atmosphere, the C / Si ratio for obtaining pure silicon carbide varies, and in this case, the C / Si ratio is not necessarily limited to the above range.

The effect of sintering of free carbon is very weak compared to that of carbon derived from a non-metallic sintering aid coated on the surface of silicon carbide powder described later. Can be ignored.

In order to obtain a solid in which the silicon source and the carbon source are homogeneously mixed, the mixture of the silicon source and the carbon source is cured to form a mixed solid, if necessary. As a curing method, a method of crosslinking by heating,
Examples include a method of curing with a curing catalyst, and a method of using an electron beam or radiation. The curing catalyst can be appropriately selected according to the carbon source, but in the case of a phenol resin or a furan resin, toluene sulfonic acid, toluene carboxylic acid, acetic acid,
Acids such as oxalic acid, hydrochloric acid, sulfuric acid, and maleic acid, and amines such as hexamine are used.

The mixed solid is heated and carbonized as required. This is done in a non-oxidizing atmosphere such as nitrogen or argon.
The heating is performed by heating the solid at 0 ° C. to 1000 ° C. for 30 minutes to 120 minutes.

The heated and carbonized mixed solid is further heated to a temperature of 1350 ° C. or more in a non-oxidizing atmosphere such as argon.
Heating at a temperature of not more than ℃ produces silicon carbide. The firing temperature and time can be appropriately selected according to the desired properties such as the particle size.
Firing at 900 ° C. is desirable.

In order to further purify the high-purity silicon carbide powder, heat treatment may be performed at 2000 to 2100 ° C. for 5 to 20 minutes during the above-mentioned firing.

As described above, in particular, as a method for producing high-purity silicon carbide powder, a method for producing a single crystal (Japanese Patent Application Laid-Open No.
No. 48605), a method for producing a raw material powder,
That is, high-purity tetraalkoxysilane, at least one selected from tetraalkoxysilane polymers is used as a silicon source, a high-purity organic compound that generates carbon by heating is used as a carbon source, and these are uniformly mixed. The resulting mixture is heated and fired in a non-oxidizing atmosphere to obtain a silicon carbide powder, and a silicon carbide powder is obtained.
Maintain at a temperature of 1700 ° C. or more and less than 2000 ° C., and maintain the temperature at a temperature of
A post-treatment step of performing heating at least once for up to 20 minutes, and obtaining the silicon carbide powder having a content of each impurity element of 0.5 ppm or less by performing the two steps. A method for producing high-purity silicon carbide powder can be used.

The sintering step will be described in more detail. In the sintering step, a mixture of silicon carbide powder, a non-metallic sintering aid, and optionally a nitrogen source (hereinafter, sometimes referred to as a mixture of silicon carbide powder) is heated to a temperature of 200.
This is a step of performing sintering by hot pressing in a non-oxidizing atmosphere at 0 to 2400 ° C and a pressure of 300 to 700 kg / cm ² .

As the nonmetallic sintering aid, a substance that generates carbon by heating is used, and an organic compound that generates carbon by heating or silicon carbide powder whose surface is coated with these compounds (particle size: 0.1 to 0.2). About 01 to 1 μm).
The former is preferred from the viewpoint of the effect.

Examples of the organic compound that generates carbon by heating include coal tar pitch, pitch tar, phenolic resin, furan resin, epoxy resin, phenoxy resin, and monosaccharides such as glucose and the like having a high residual carbon ratio. Various saccharides such as oligosaccharides such as sucrose and polysaccharides such as cellulose and starch. These are preferably those that are liquid at room temperature, those that dissolve in a solvent, those that are softened by heating such as thermoplastic or heat-meltable, or those that become liquid, for the purpose of being homogeneously mixed with silicon carbide powder. Among them, a phenol resin having high strength of the obtained molded body, particularly a resol-type phenol resin is preferable.

The organic compound that forms carbon by heating generates an inorganic carbon-based compound such as carbon black or graphite on the particle surface (near) when heated, and efficiently forms a surface oxide film of silicon carbide during sintering. It is thought that it works effectively as a sintering aid to be removed.

When obtaining the mixture with the silicon carbide powder, the nonmetallic sintering aid is preferably dissolved or dispersed in a solvent and mixed. The solvent is suitable for the compound used as the nonmetallic sintering aid, specifically,
For a phenol resin that is an organic compound that generates carbon by suitable heating, lower alcohols such as ethyl alcohol, ethyl ether, acetone, and the like can be selected. In addition, it is preferable to use a non-metallic sintering aid and a solvent having a low impurity content.

If the amount of the nonmetallic sintering additive is too small, the density of the sintered body will not increase, while if it is too large, the free carbon contained in the sintered body will increase, which may hinder high density. Therefore, although it depends on the type of the nonmetallic sintering aid to be used, it is generally preferable to adjust the amount to be 10% by weight or less, preferably 2 to 5% by weight. This amount can be determined by previously quantifying the amount of silica (silicon oxide) on the surface of the silicon carbide powder using hydrofluoric acid and calculating the amount stoichiometrically sufficient for its reduction.

The amount of carbon added here means that the silica determined by the above method is carbon derived from the nonmetallic sintering aid, and is reduced by the following chemical reaction formula. It is a value obtained in consideration of the residual carbon ratio after thermal decomposition of the nonmetallic sintering aid (the ratio of carbon generated in the nonmetallic sintering aid) and the like.

[0040]

Embedded image SiO ₂ + 3C → SiC + 2CO

In the silicon carbide sintered body, the total of carbon atoms derived from silicon carbide and carbon atoms derived from the nonmetallic sintering aid contained in the silicon carbide sintered body is 30.
It is preferable that the content is more than 40% by weight and more than 40% by weight.
When the content is 30% by weight or less, the proportion of impurities contained in the sintered body increases, and when the content exceeds 40% by weight, the carbon content increases, and the density of the obtained sintered body decreases. It is not preferable because various properties such as strength and oxidation resistance of the body deteriorate.

In the above-mentioned silicon carbide sintered body, first, silicon carbide powder and a nonmetallic sintering aid are mixed homogeneously. Dissolve in a solvent such as alcohol and mix well with silicon carbide powder. At this time, if desired, a nitrogen source can be added together with the nonmetallic sintering aid.

The mixing can be performed by known mixing means, for example, a mixer, a planetary ball mill, or the like. The mixing is preferably performed for 10 to 30 hours, particularly for 16 to 24 hours. After thorough mixing, the solvent is removed at a temperature compatible with the physical properties of the solvent, for example, at a temperature of 50 to 60 ° C. in the case of the above-mentioned ethyl alcohol, and the mixture is evaporated to dryness, and then sieved. To obtain a raw material powder of the mixture. From the viewpoint of high purification, the material of the ball mill container and the balls needs to be a synthetic resin containing as little metal as possible. In drying, a granulator such as a spray dryer may be used.

In the sintering step, a molded body of the mixture of the silicon carbide powder or the mixture of the silicon carbide powder obtained by the molding step described below is placed in a molding die, and the temperature is set to 2,000.
It is preferable to perform sintering by hot pressing in a non-oxidizing atmosphere at a temperature of ２2400 ° C., a pressure of 300-700 kgf / cm ² .

From the viewpoint of the purity of the obtained sintered body, a part of the molding die is used so that the mixture of the silicon carbide powder or the molded body does not come into direct contact with the metal part of the molding die. Alternatively, it is preferable to use a material made entirely of graphite or to interpose a Teflon sheet or the like in a molding die.

The pressure of the hot press is 300-70.
Although pressure can be applied under the condition of 0 kgf / cm ² ,
When a pressure of 400 kgf / cm ² or more is applied, it is necessary to select a hot-pressed part used here, such as a die or a punch, having good pressure resistance.

In the hot press, prior to the hot press, a heating and heating step is performed under the following conditions to sufficiently remove impurities and to completely carbonize the nonmetallic sintering aid.
It is preferable to carry out under the above conditions.

In the heating and temperature raising step, it is preferable to perform the following two steps of a first heating and temperature raising step and a second heating and temperature raising step. In the first heating and temperature raising step, first, the inside of the furnace is slowly heated from room temperature to 700 ° C. under vacuum. If it is difficult to control the temperature of the high-temperature furnace, 70
Although the temperature may be continuously raised to 0 ° C.,
The inside of the furnace is set to 10 ^-4 torr, the temperature is gradually raised from room temperature to 200 ° C., and the temperature is maintained for a certain time. Thereafter, the temperature is further gradually increased and heated to 700 ° C. Further, it is kept at a temperature of about 700 ° C. for a certain time.
In the first heating and temperature raising step, desorption of adsorbed moisture and organic solvent is performed, and further, carbonization by thermal decomposition of the nonmetallic sintering aid is performed. A suitable range of the time for maintaining the temperature at about 200 ° C. or about 700 ° C. is selected depending on the size of the sintered body. Whether the holding time is sufficient or not can be determined at a time when the decrease in the degree of vacuum is reduced to some extent. If rapid heating is performed at this stage, the removal of impurities and the carbonization of the nonmetallic sintering aid will not be sufficiently performed, which may cause cracks or voids in the molded product, which is not preferable.

In the first heating and heating step, for example, for a sample of about 5 to 10 g, 10 ^-4 t
orr, slowly raise the temperature from room temperature to 200 ° C,
The temperature is maintained for about 30 minutes, and then the temperature is further gradually increased and heated to 700 ° C.
The time required to reach 00 ° C. is about 6 to 10 hours, preferably about 8 hours. Further, at a temperature around 700 ° C, 2
It is preferable to hold for about 5 hours.

In the second heating and temperature raising step, the temperature is raised from 700 ° C. to 1500 ° C. in vacuum for about 6 to 9 hours under the above-mentioned conditions. Hold for ~ 5 hours. It is considered that a reduction reaction of silicon dioxide and silicon oxide is performed in the second heating and temperature raising step. It is important to complete this reduction reaction sufficiently to remove oxygen bonded with silicon.
The holding time at the temperature of 0 ° C. is the time until the generation of carbon monoxide as a by-product by this reduction reaction is completed, that is, the degree of vacuum decreases little, and the vacuum at about 1300 ° C., which is the temperature before the start of the reduction reaction. It is necessary to do it until it recovers. By the reduction reaction in the second heating and temperature raising step, silicon dioxide which adheres to the surface of the silicon carbide powder and hinders densification and causes large grain growth is removed. The gas containing SiO and CO generated during this reduction reaction accompanies impurity elements, but since these generated gases are constantly discharged and removed by the vacuum pump from the reaction furnace, this gas is also required from the viewpoint of high purity. It is preferable to keep the temperature sufficiently.

After the heating and temperature raising steps are completed, it is preferable to perform a high-pressure hot press. Temperature is 1500 ° C
When the temperature rises to a higher temperature, sintering starts. At this time, 300 to 700 kgf / cm ² is used to suppress abnormal grain growth.
Pressurization is started as a guide to the extent. Thereafter, an inert gas is introduced to make the inside of the furnace a non-oxidizing atmosphere.
As this inert gas, nitrogen or argon is used, but since it is non-reactive even at high temperatures,
It is preferable to use argon gas.

In the hot press, after the inside of the furnace is made a non-oxidizing atmosphere, the temperature is set to 2000 to 2400 ° C. and the pressure is set to 300.
Heating and pressurizing are performed so that the pressure becomes 700 kgf / cm ² . The pressure at the time of pressing can be selected according to the particle size of the raw material powder. If the raw material powder has a small particle size, a suitable sintered body can be obtained even if the pressure at the time of pressing is relatively small. Also, here, the maximum temperature is from 1500 ° C. to 2000 to 2
The temperature rise to 400 ° C. takes 2-4 hours, while sintering proceeds rapidly at 1850-1900 ° C. Furthermore, the sintering is completed by holding at this maximum temperature for 1 to 3 hours.

If the maximum temperature is less than 2000 ° C., the densification will be insufficient, and if it exceeds 2400 ° C., the powder or the raw material of the compact will be undesirably sublimated (decomposed). On the other hand, if the pressing condition is less than 500 kgf / cm ² , the densification becomes insufficient, and 700 kgf / cm ²
Exceeding the range causes breakage of a mold such as a graphite mold, which is not preferable in terms of manufacturing efficiency.

Also in the hot press, from the viewpoint of maintaining the purity of the obtained sintered body, it is preferable to use a high-purity graphite raw material for the graphite mold and the heat insulating material of the heating furnace used here. A high-purity product is used. Specifically, it is desirable that the product be baked sufficiently at a temperature of 2500 ° C. or more and generate no impurities at the sintering temperature. Further, as for the inert gas used, it is preferable to use a high-purity product with few impurities.

By performing the sintering step, a silicon carbide sintered body having excellent characteristics can be obtained. However, from the viewpoint of increasing the density of the finally obtained sintered body, prior to the sintering step, The molding step described below may be performed. Hereinafter, a forming step which can be performed prior to the sintering step will be described. Here, the molding step means that a mixture of silicon carbide powder is placed in a molding die, heated at a temperature range of 80 to 300 ° C. for 5 to 60 minutes, and pressed to form a molded product of the mixture of silicon carbide powder in advance. (Hereinafter, may be referred to as a molded body). Here, it is preferable that the mixture of the silicon carbide powder is filled into the mold as closely as possible from the viewpoint of increasing the density of the final silicon carbide sintered body. When this molding step is performed, the mixture of bulky silicon carbide powder can be compacted in advance when the sample is filled for hot pressing, so that a molded article having a large thickness can be easily manufactured by repeating this molding step. .

The heating temperature is 80 to 300 ° C., preferably 120 to 140 ° C., depending on the characteristics of the nonmetallic sintering aid.
° C, pressure 60-60 kgf / cm ² ,
It is pressed so that the density of the filled raw material powder is 1.5 g / cm ³ or more, preferably 1.9 g / cm ³ or more, and is pressed for 5 to 60 minutes, preferably 20 to 40 minutes. By holding, a molded body composed of a mixture of silicon carbide powder is obtained. Here, the density of the compact is difficult to increase as the average particle diameter of the powder becomes smaller, and it is preferable to adopt a method such as vibration filling when disposing the compact in a molding die in order to increase the density. . Specifically, the powder having an average particle diameter of about 1 μm has a density of 1.8 g / cm ³ or more, and the powder having an average particle diameter of about 0.5 μm has a density of 1.5 g / cm ³ or more. More preferred. 1.5g density for each particle size
/ Cm ³ or less than 1.8 g / cm ³ , it is difficult to increase the density of the finally obtained sintered body.

Before the next sintering step, the compact is
Cutting can be performed so as to be compatible with a hot press mold used in advance. Preferably, the molded body surface-coated with a nonmetallic sintering aid is placed in a molding die under the aforementioned temperature of 2000 to 2400 ° C., a pressure of 300 to 700 kgf / cm ² , and a non-oxidizing atmosphere, and hot-pressed. That is, a sintering step is performed to obtain a silicon carbide sintered body of high density and high purity. At this time, if at least 500 ppm of a nitrogen component is contained in the silicon carbide powder and / or together with the nonmetallic sintering aid, nitrogen is substantially uniformly dispersed in the silicon carbide sintered body at 200 ppm after sintering. About 1Ω
Thus, a silicon carbide sintered body having a volume resistivity of at most cm is obtained.

The silicon carbide sintered body obtained by the above manufacturing method is sufficiently densified, and has a density of 2.9 g.
/ Cm ³ or more. The density of the obtained sintered body is 2.9 g.
If it is less than / cm ³ , mechanical properties such as bending strength and breaking strength and electrical physical properties will be reduced, and particles will be increased, and contamination will be deteriorated. More preferably, the density of the silicon carbide sintered body is 3.0 g / cm ³ or more.

When the silicon carbide sintered body is a porous body, it is inferior in heat resistance, oxidation resistance, chemical resistance and mechanical strength, is difficult to clean, has minute cracks, and minute pieces become pollutants. , And has poor physical properties such as having gas permeability, and also causes problems such as limited use.

The total content of impurity elements in the silicon carbide sintered body is preferably 10 ppm or less, more preferably 5 ppm or less, and the impurity content obtained by these chemical analyzes has a meaning as a reference value. It's just
Practically, the evaluation differs depending on whether the impurities are uniformly distributed or locally unevenly distributed. Therefore, those skilled in the art generally evaluate the extent to which impurities contaminate the silicon carbide sintered body under predetermined heating conditions by using various practical devices. The solid obtained by homogeneously mixing the liquid silicon compound, the nonmetallic sintering aid, and the polymerization or cross-linking catalyst was heated and carbonized in a non-oxidizing atmosphere, and then further subjected to non-oxidizing. According to the production method including the firing step of firing in a neutral atmosphere, the total content of the impurity elements contained in the silicon carbide sintered body can be reduced to 10 ppm or less. In addition, a silicon source and a nonmetallic sintering aid used in the step of producing the silicon carbide powder and the step of producing a silicon carbide sintered body from the silicon carbide powder, and a non-oxidizing atmosphere used for forming a non-oxidizing atmosphere. Active gas, each purity, each impurity element content 10ppm
Hereinafter, the content is more preferably 500 ppm or less, but is not necessarily limited to this as long as it is within an allowable range of purification in the heating and sintering steps. Here, the impurity element substantially means Si, C, O, N, halogen,
And elements other than noble gases.

Since the silicon carbide sintered body is obtained by using a nonmetallic sintering aid, it is a high-density product having a density of 2.9 g / cm ³ or more, is obtained with good sintering, and has a high conductivity. Tend to be a polycrystalline semiconductor that exhibits In other words, conduction electrons contributing to electric conduction flow between silicon carbide crystals with the grain boundaries interposed therebetween, and thus the junction between the grain boundary phase and silicon carbide is also important for the development of conductivity. The transfer characteristics of conduction electrons are roughly classified into tunnel conduction and thermally excited conduction.

When the silicon carbide sintered body contains nitrogen, its content is preferably 150 ppm, more preferably 200 ppm. From the viewpoint of stability, it is preferable that nitrogen is contained in a solid solution state.

The silicon carbide sintered body contains 150 p
Since the barrier of the space charge layer generated at the grain boundary becomes about 0.15 eV or less when contained in a solid solution state of pm or more, good conductivity is achieved. The volume resistivity of the silicon carbide sintered body at this time indicates a 10 ⁰ Ω · cm. Nitrogen content 20
When the concentration is 0 ppm or more, the barrier of the space charge layer at the grain boundary becomes 0.026 eV or less. Even at room temperature (300 K), this barrier can be jumped by thermal excitation, and not only thermal excitation conduction occurs but also tunnel conduction occurs. In general, it is known that the temperature dependence of the volume resistance of a semiconductor decreases with an increase in temperature (NTC region) and then starts to increase (PTC region). At this time, the smaller the temperature change of the volume resistivity, the easier the temperature control when used as a current-carrying heating element. Here, the greater the amount of nitrogen solid solution contained in the silicon carbide sintered body, the more the localization temperature of the NTC region and the PTC region shifts to a lower temperature side. That is, as in the silicon carbide sintered body of the present invention, the content of nitrogen is 150 ppm or more, preferably 2 ppm or more.
By setting the amount to 00 ppm or more, the NTC region in the low-temperature portion where the change in volume resistivity is the largest can be reduced, and thereby the amount of change in volume resistivity due to a temperature change from room temperature to high temperature can be reduced.

The silicon carbide sintered body obtained through the step of manufacturing the silicon carbide sintered body is processed into a desired shape,
After processing such as grinding and polishing, a step of washing the silicon carbide sintered body is performed. In addition, as a processing method of machining, grinding, and polishing, a known method can be used. When nitrogen is introduced, electric discharge machining is preferable.

In the step of cleaning the silicon carbide sintered body,
And will be described in detail. Cleaning the silicon carbide sintered body
By performing the process, any defects existing on the surface and near the surface
1.0 × 10¹¹atom / cm^TwoLess than, preferred
Or 5.0 × 10^Tenatom / cm^TwoLess, even more preferred
Or 1.0 × 10^Tenatom / cm ^TwoLess than silicon carbide
An elementary sintered body can be easily obtained.

The step of cleaning the silicon carbide sintered body includes:
A silicon carbide sintered body (hereinafter, sometimes referred to as a body to be cleaned) is sequentially treated by a step of dipping in a semi-aqueous organic solvent, a step of dipping in an inorganic acid aqueous solution, and a step of dipping in pure water. It is a process. By performing these steps in this order, first, organic substances (eg, oil films, fingerprints, and waxes) on the surface are removed by the quasi-aqueous organic solvent, and then the metal elements on the surface and near the surface by the aqueous inorganic acid solution are removed. It becomes possible. In addition, it is preferable that the step of immersing in an aqueous ammonium solution is performed between the above steps, and that the used organic solvent and particles are more easily removed.

The step of immersing in the quasi-aqueous organic solvent is a step of removing organic substances adhering to the surface and the vicinity of the surface of the silicon carbide sintered body.

The quasi-aqueous organic solvent refers to an organic solvent that is soluble in water and a solvent that is insoluble in water but can be easily removed by washing with water. That is, in the present invention, the quasi-aqueous organic solvent includes those which are soluble in water, those in which a hydrophilic group is partially introduced into a water-insoluble solvent, and those in which a surfactant is added in advance. Specific examples of the quasi-aqueous organic solvent include petroleum hydrocarbons, organic acid esters, glycol ethers, mixed solvents thereof, and mixtures of these solvents or mixed solvents with surfactants. As the mixed solvent and the mixture, a mixed solvent of a petroleum hydrocarbon and an organic acid ester or glycol ether, a mixture of a petroleum hydrocarbon and an organic acid ester or glycol ether and a surfactant, a petroleum hydrocarbon and a surfactant And a mixture of an organic ester and a surfactant.

Examples of the petroleum hydrocarbon include aliphatic hydrocarbons represented by naphthene and hexane.

Examples of the organic acid esters include fatty acid esters (for example, fatty acid methyl esters), glycerin esters, sorbitan esters and the like.

Examples of the glycol ether include propylene glycol ether, propylene glycol methyl ether, diethylene glycol dimethyl ether and the like.

The surfactant is not particularly limited as long as it fulfills the desired purpose, but may be polyoxyethylene fatty acid methyl, alkylamine oxide, polyoxyalkylene glycol, or an ethylene oxide or propylene oxide adduct of alkylamine. And the like are preferable.

In the step of dipping in the quasi-aqueous organic solvent, the time for dipping the silicon carbide sintered body depends on the amount and type of the organic substance adhered thereto, but is preferably 2 minutes to 60 minutes, and more preferably 10 minutes to 10 minutes. 30 minutes is more preferable, and 10 minutes to 15 minutes is still more preferable.

In the step of dipping in the quasi-aqueous organic solvent, it is effective to heat to 50 to 70 ° C. from the viewpoint of increasing the dissolving power of the attached organic substance.

The step of immersing in the inorganic acid aqueous solution is a step of removing metal impurities on the surface and near the surface of the silicon carbide sintered body.

Examples of the inorganic acid aqueous solution include a hydrofluoric acid aqueous solution, a nitric acid aqueous solution, a sulfuric acid aqueous solution, a hydrochloric acid aqueous solution, a hydrogen peroxide solution, an ozone water, and a mixed acid aqueous solution thereof. Examples of the mixed acid aqueous solution include a hydrofluoric nitric acid aqueous solution, a mixed acid aqueous solution of hydrofluoric nitric acid and sulfuric acid, and a mixed acid aqueous solution of hydrofluoric acid and hydrochloric acid.

The concentration of the aqueous inorganic acid solution is 0.3
The content is preferably from 68 to 68% by weight, more preferably from 1 to 40% by weight, still more preferably from 5 to 10% by weight. This concentration is 0.
If it is less than 3% by weight, the effect of removing metal impurities may be insufficient. If it exceeds 68% by weight, the roughness of the surface of the object to be cleaned may be reduced.

To the inorganic acid aqueous solution, a nonionic surfactant may be added for the purpose of preventing reattachment of the metal ions once eluted. As the nonionic surfactant,
The same is as described above.

In the step of dipping in the inorganic acid aqueous solution, the time for dipping the silicon carbide sintered body is from 5 minutes to 120 minutes.
Minutes, more preferably 10 minutes to 60 minutes, even more preferably 20 minutes to 30 minutes.

The step of immersion in the pure water is a step of removing residual components attached to the surface and the vicinity of the surface of the silicon carbide sintered body by using the solvent and the aqueous solution used in each step of the cleaning step.

The pure water preferably has a purity of 100 ppt or less and a specific resistance of 16 to 18 MΩ, and more preferably has a purity of less than 10 ppt.

The step of immersing in the pure water is preferably performed by an overflow method so that the step of immersion is always performed with a new solution.

In the step of immersing in the aqueous ammonium solution, the organic solvent in the previous step, which is presumed to be attached in a minute amount on the surface of the silicon carbide sintered body and in the vicinity of the surface, is removed by the surface active effect, and particles are removed. This is the step of removing.

Examples of the aqueous ammonium solution include aqueous solutions of ethylene oxide or propylene oxide addition polymers such as alkylamine oxides and alkylamines, and tetraalkylammonium halides (eg, tetramethylammonium halide) and tetraalkylammonium perchlorates. An aqueous solution of a quaternary ammonium salt of
Ammonia water, and a mixed aqueous solution of these and hydrogen peroxide water, and the like can be given. Of these, aqueous quaternary ammonium salts such as tetraalkylammonium halides and tetraalkylammonium perchlorates, and aqueous ammonia are preferred.

The aqueous ammonium solution varies depending on the type and the like, but usually has a surface tension of 25 to 35 dyne / c.
It is preferable to use m.

The ammonium aqueous solution may be used alone or in combination of two or more.

In the step of dipping in the ammonium aqueous solution, the time for dipping the silicon carbide sintered body is from 5 minutes to 1 minute.
20 minutes are preferable, 10 minutes to 60 minutes are more preferable, and 2 minutes
0 to 30 minutes is more preferable.

In the cleaning step, at least one of the cleaning steps is performed from the viewpoint that impurities present on the surface and near the surface are more easily dissolved by applying physical vibration to the object to be cleaned. It is preferable that the cleaning is performed while irradiating the aqueous solution with ultrasonic vibration, and the cleaning may be performed while vibrating the object to be cleaned or sweeping the ultrasonic frequency. This is particularly effective when performed in a step of dipping in an aqueous solution of an inorganic acid.

In the washing step, the temperature of the solvent or aqueous solution in at least one of the above steps is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, in order to improve the dissolving ability of various impurities and deposits. Particularly preferably 50
It is preferable to carry out the reaction at a temperature of not less than ° C. The upper limit of this temperature is equal to or lower than the boiling point of the solvent or aqueous solution used. This is particularly effective when performed in a step of immersion in a quasi-aqueous organic solvent.

In the washing step, a step of dipping in washing water may be performed between each step. When performing the step of immersing in the washing water, for example, in the step of immersing in a semi-aqueous organic solvent,
By easily washing away the solvent attached to the object to be cleaned,
The aqueous solution in the next step is less likely to be contaminated.

As the washing water, pure water, distilled water,
Ion-exchanged water and the like can be mentioned, but from the viewpoint of preventing reverse contamination of the object to be cleaned in the step of immersing in cleaning water, the pure water is preferable.

In the step of dipping in the washing water, the time for dipping the silicon carbide sintered body is preferably 2 minutes to 60 minutes, more preferably 5 minutes to 30 minutes, and further preferably 10 minutes to 20 minutes.

The step of immersion in the washing water may be performed by an overflow method so that the washing is always performed with the new solution.

As the apparatus and equipment used in the step of cleaning the silicon carbide sintered body, polyvinyl chloride (PVC), which is excellent in chemical resistance, is preferable, and particularly, highly purified PVC is preferable. . The ultrasonic generator, the heater, and the like are preferably those whose surfaces are subjected to Teflon processing.

The silicon carbide sintered body obtained by the above-described manufacturing method including the step of manufacturing the silicon carbide sintered body and the step of cleaning the silicon carbide sintered body has a high density, Since there are few impurities, it can be suitably used for various semiconductor members and electronic components. Examples of various semiconductor members include members for which high purity and particle free are desired, such as a dummy wafer, a heater, a plasma etching electrode, and an ion implanter target.

[0096]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 (Production of Sintered Silicon Carbide) Resol type phenol resin containing amine (residual carbon ratio after thermal decomposition: 50%), 6 g and one particle size distribution maximum value with an average particle size of 0.5 μm Was mixed in a wet ball mill in 50 g of ethanol or acetone solvent, dried, and formed into a cylindrical shape having a diameter of 20 mm and a thickness of 10 mm.
The amount of the phenol resin and the amount of the amine contained in the molded product were 6 wt% and 0.1 wt%, respectively. This compact was sintered by a hot press method under a pressure of 700 kgf / cm ² under an argon gas atmosphere at a temperature of 2300 ° C. for 3 hours to produce a silicon carbide sintered body.

(Processing of Silicon Carbide Sintered Body) The obtained silicon carbide sintered body was processed into a 40 × 40 × 2 t flat plate, and one surface was polished with a rough surface, and the other surface was polished with a mirror surface. In addition, the surface cleanliness (impurity adhesion amount) of the processed silicon carbide sintered body is 1 × 10 ¹³ to 1 × 10 ¹⁶ atoms / c.
m ² . The density of the obtained silicon carbide sintered body was 3.13 g / cm ³ (measured according to JIS R1634).
The total content of impurities was 3.5 ppm (measured by ICP-MS or the like). The total content of impurities referred to here is
Does not contain impurities on or near the surface.

(Washing of Silicon Carbide Sintered Body) A processed silicon carbide sintered body was added to a stock solution of a semi-aqueous organic solvent (mixed solvent of petroleum hydrocarbon, organic acid ester and nonionic surfactant) at 50 ° C. Ultrasonic at (100V-26 ± 2kHz)
Immersion for 15 minutes while irradiating with water, rinsing with water, and then fluoric nitric acid aqueous solution (38% hydrofluoric acid: 68% nitric acid: water = 1: 1:
20), and then immersed in pure water to obtain a silicon carbide sintered body of Example 1.

(Evaluation) The surface cleanliness (impurity amount) of the obtained silicon carbide sintered body of Example 1 was measured. The surface cleanliness of the silicon carbide sintered body is from 8 × 10 ⁹ to 1 × 10 ^{11 at.}
ms / cm ² , and details are shown in Table 1. In addition, each of the above treatments was carried out at a normal temperature of the aqueous solution except for the treatment of immersion in the semi-aqueous organic solvent. The measurement of surface cleanliness was performed as follows.

(Measurement of surface cleanliness (impurity amount)) The measurement of surface cleanliness (impurity amount) was carried out using light elements (B, Na, Al).
Discloses a method for washing impurities on a surface of a silicon carbide sintered body using an aqueous solution containing hydrofluoric nitric acid and nitric acid at a concentration of 1% to extract impurities.
coupled Plasma Mass Spectro
meter (inductively coupled plasma mass spectrometer) "). Other elements are immersed in a pure water solution and dried, and then subjected to TXRF (“Total Reflection”).
X-Ray Fluorescence meter (total reflection X-ray fluorescence spectrometer) "). Note that TXR
When analyzing in F, the relative sensitivity coefficient in silicon was used. In addition, the fact that the ICP-MS analysis value and the TXRF analysis value are substantially equal indicates that K, Cr, Fe, Ni, Cu, Zn
Confirmed by the analysis value.

[Example 2] Instead of washing the silicon carbide sintered body of Example 1, the processed silicon carbide sintered body was immersed in glycol ether for 20 minutes and immersed in a quaternary ammonium salt aqueous solution for 30 minutes. , Hydrofluoric acid aqueous solution (38% hydrofluoric acid: 6
(8% nitric acid: water = 1: 1: 20) for 30 minutes, and a silicon carbide sintered body of Example 2 was obtained in the same manner as in Example 1 except that the silicon carbide was further immersed in pure water. (Evaluation) The surface cleanliness of the obtained silicon carbide sintered body of Example 2 was measured. The surface cleanliness of the silicon carbide sintered body is 8
× 10 ^{9 to} 9 × 10 ¹⁰ atoms / cm ² , and details are shown in Table 1. In addition, each of the above treatments was performed with the temperature of the solvent and the aqueous solution at room temperature.

Example 3 In the cleaning of the silicon carbide sintered body of Example 1, ultrasonic waves (100 V-26 ± 2
kHz) was obtained in the same manner as in Example 1 except that the silicon carbide sintered body of Example 3 was irradiated. (Evaluation) The surface cleanliness of the obtained silicon carbide sintered body of Example 3 was measured. The surface cleanliness of the silicon carbide sintered body is 8
× 10 ^{9 to} 9 × 10 ¹⁰ atoms / cm ² , and details are shown in Table 1.

Example 4 In cleaning the silicon carbide sintered body of Example 1, the temperature of the solvent and the aqueous solution was set to 70 in each treatment.
A silicon carbide sintered body of Example 4 was obtained in the same manner as in Example 1 except that the temperature was changed to ° C. (Evaluation) The surface cleanliness of the obtained silicon carbide sintered body of Example 4 was measured. The surface cleanliness of the silicon carbide sintered body is 8
× 10 ⁹ to less than 1 × 10 ¹¹ atoms / cm ² ,
Details are shown in Table 1.

Example 5 Instead of washing the silicon carbide sintered body of Example 1, the processed silicon carbide sintered body was replaced with a semi-aqueous organic solvent (a petroleum hydrocarbon, an organic acid ester and a nonionic surfactant). Immersion for 15 minutes at 50 ° C. while irradiating ultrasonic waves (100 V-26 ± 2 kHz) at 50 ° C., immersion for 30 minutes in quaternary ammonium salt aqueous solution, and hydrofluoric acid / nitric acid / sulfuric acid aqueous solution (38 % Hydrofluoric acid: 68% nitric acid: 9
8% sulfuric acid: water = 1: 1: 1: 20) for 30 minutes, and then immersed in pure water in the same manner as in Example 1 except that the sample was immersed in pure water.
Was obtained. The above treatments were carried out with the temperature of the aqueous solution at normal temperature except for the treatment of immersion in the semi-aqueous organic solvent. (Evaluation) The surface cleanliness of the obtained silicon carbide sintered body of Example 5 was measured. The surface cleanliness of the silicon carbide sintered body is 4
× 10 ^{9 to} less than 9 × 10 ¹⁰ atoms / cm ² ,
The analysis values of Zn and Cr obtained here are the lower detection limits of TXRF. Details are shown in Table 1.

Comparative Example 1 In cleaning the silicon carbide sintered body of Example 1, except that it was not immersed in an aqueous solution of hydrofluoric / nitric acid,
In the same manner as in Example 1, a silicon carbide sintered body of Comparative Example 1 was obtained. (Evaluation) The surface cleanliness of the obtained silicon carbide sintered body of Comparative Example 1 was measured. The surface cleanliness of the silicon carbide sintered body is 1
× 10 ¹¹ to less than 1 × 10 ¹⁵ atoms / cm ² ,
Details are shown in Table 1.

[Comparative Example 2] In cleaning the silicon carbide sintered body of Example 1, except that the silicon carbide sintered body was not immersed in a quasi-aqueous organic solvent.
In the same manner as in Example 1, a silicon carbide sintered body of Comparative Example 2 was obtained. (Evaluation) The surface cleanliness of the obtained silicon carbide sintered body of Comparative Example 2 was measured. The surface cleanliness of the silicon carbide sintered body is 1
Less than × 10 ¹⁰ to 1 × 10 ¹⁴ atoms / cm ² ,
Details are shown in Table 1.

[0108]

[Table 1]

From Examples 1 to 5 and Comparative Examples 1 and 2, the silicon carbide sintered body of the present invention has a surface of less than 1 × 10 ¹¹ atoms / cm ² applicable to various semiconductor members and electronic members. It is clear that it is clean, high density and high purity.

[0110]

As described above, the present invention has a high density,
In addition, it is possible to provide a silicon carbide sintered body with few organic and inorganic impurities existing on and near the surface.

Claims (3)

[Claims] 1. The method according to claim 1, wherein the amount of impurities present on the surface and in the vicinity of the surface of the silicon carbide sintered body is less than 1.0 × 10 ¹¹ atoms / cm ² , and the density is 2.9 g / cm ² or more. Silicon carbide sintered body. 2. The silicon carbide sintered body according to claim 1, wherein the total content of impurity elements in the silicon carbide sintered body is 10 ppm or less. 3. A mixture of a silicon carbide powder and a non-metallic sintering aid at a temperature of 2000 to 2400 ° C. and a pressure of 300 to 7
00kg / cm ^2, a non-oxidizing atmosphere and a sintering step of hot pressing, the claims, wherein it obtained from the production method comprising a cleaning step of wet cleaning a silicon carbide sintered body through the sinter process Item 3. The silicon carbide sintered body according to item 1 or 2.