JP2008074667A - Silicon carbide sintered compact sheet and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high purity silicon carbide sintered compact sheet low in temperature dependency of resistance, and a method of manufacturing the same. <P>SOLUTION: The method of manufacturing the silicon carbide sintered compact sheet includes a step for obtaining a slurry like powdery mixture containing silicon carbide powder and a non-metallic sintering aid, a step for forming a sheet like tentative formed body from silicon carbide slurry using a tape casting method and a step for obtaining the silicon carbide sintered compact sheet by sintering the sheet like tentative formed body by a hot press in a state of being held between carbon made spacers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a silicon carbide sintered body and a method for producing the same, and more particularly to a silicon carbide sintered body sheet and a method for producing the same.

  A heater composed of a silicon carbide sintered body has been proposed as a heater for various heat treatments of a semiconductor wafer because the usable atmosphere is not limited and is excellent in rapid temperature rise / fall characteristics. As one embodiment of such a heater, a sheet-like silicon carbide sintered body heater has been proposed (see, for example, Patent Documents 1 and 2).

Patent Document 1 discloses a step of adding silicon carbide, carbon powder and a binder to water and mixing with a pot mill to obtain a slurry; a step of forming a green sheet by a tape casting method; And a method of forming a porous sheet on a silicon carbide sheet heater using a reactive sintering method.
However, the silicon carbide sheet heater according to Patent Document 1 is unsuitable for the heater because the temperature dependence of the resistance is high because Si is excessive due to silicon (Si) impregnation.

On the other hand, Patent Document 2 discloses a silicon carbide sintered body in which a green sheet is formed by a tape casting method from a slurry in which a silicon carbide powder is mixed with a sintering aid, an organic binder, and a plasticizer, and the green sheet is degreased and fired. A method of manufacturing a sheet is disclosed.
However, since the silicon carbide sintered body sheet according to Patent Document 2 uses a metal-based sintering aid as a sintering aid, it is difficult to use it in an environment where impurities are hated such as a semiconductor manufacturing apparatus. It was. In addition, by adding a metal-based auxiliary, it is difficult to produce a silicon carbide sintered body sheet having a uniform surface shape due to warpage of the sheet during firing.

JP 2000-313669 A JP 10-297971 A

  From the above, there has been a demand for a highly pure silicon carbide sintered body sheet having a low resistance temperature dependency and a method for producing the same.

That is, the present invention relates to the following description items.
(1) A step of obtaining a slurry-like mixed powder containing silicon carbide powder and a nonmetallic sintering aid, a step of forming a sheet-like temporary molded product from the silicon carbide slurry using a tape casting method, and a sheet-like shape And a step of obtaining a silicon carbide sintered body sheet by hot press sintering in a state where the temporary molded product is sandwiched between carbon spacers.
(2) The silicon carbide sintered body sheet according to (1), further comprising a step of heating a composite of the silicon carbide sintered body sheet and the carbon spacer in an oxidizing atmosphere to burn out the carbon spacer. Production method.
(3) The method for producing a silicon carbide sintered body sheet according to (1) or (2), wherein the nonmetallic sintering aid is a phenol resin.
(4) The method for producing a sintered silicon carbide sheet according to any one of (1) to (3), wherein the plasticizer is dioctyl phthalate.
(5) The method for producing a silicon carbide sintered body sheet according to any one of (1) to (4), wherein the silicon carbide slurry further contains polyvinyl butyral as a binder.
(6) The silicon carbide sintered body sheet according to any one of the above (1) to (5), wherein a plurality of laminated sheet-like temporary molded articles are hot-press sintered in a state of being sandwiched between carbon spacers to obtain a silicon carbide sintered body sheet A method for producing a sintered silicon carbide sheet.
(7) The method for producing a silicon carbide sintered body sheet according to any one of (1) to (6), wherein the slurry further contains a binder.
(8) The method for producing a sintered silicon carbide sheet according to any one of (1) to (7), wherein the slurry further contains a plasticizer.
(9) A silicon carbide sintered body sheet having a thickness of 240 μm or less and a bulk density of 3.15 g / cm ³ or more.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature dependency of resistance is low and the highly purified silicon carbide sintered compact sheet | seat and its manufacturing method are provided.

  Hereinafter, the present invention will be described with reference to embodiments, but it goes without saying that the present invention is not limited to the following embodiments.

[Components used in the method for producing a silicon carbide sintered sheet]
First, the component used for the manufacturing method of the silicon carbide sintered compact sheet concerning embodiment of this invention is demonstrated.
(Silicon carbide powder)
Examples of the silicon carbide powder include α-type, β-type, amorphous, and mixtures thereof. In order to obtain a high-purity silicon carbide sintered body, it is preferable to use a high-purity silicon carbide powder as the raw material silicon carbide powder. The grade of the β-type silicon carbide powder is not particularly limited, and for example, commercially available β-type silicon carbide can be used. The particle size of the silicon carbide powder is preferably small from the viewpoint of high density, specifically about 0.01 μm to 10 μm, more preferably 0.05 μm to 5 μm. If the particle size is less than 0.01 μm, handling in processing steps such as weighing and mixing tends to be difficult, and if it exceeds 10 μm, the specific surface area is small, that is, the contact area with the adjacent powder is small, and high This is not preferable because it is difficult to increase the density.

  Here, “particle size” means the average particle size of silicon carbide fine particles when the particle size of individual particles is measured for 200 silicon carbide fine particles arbitrarily selected from a photograph taken with a scanning electron microscope (SEM). It shall be said. The particle size of the silicon carbide powder can be made into a powder of 1 μm to 20 μm, for example, by pulverizing the obtained silicon carbide powder with a jet mill.

  The high-purity silicon carbide powder includes, for example, a silicon source containing at least one silicon compound, a carbon source containing an organic compound that generates carbon by heating at least one kind, and a polymerization or crosslinking catalyst. It can be obtained by a step of firing in a non-oxidizing atmosphere the powder obtained after being dissolved in and dried.

  As a silicon source containing a silicon compound (hereinafter referred to as “silicon source”), a liquid source and a solid source can be used in combination, but at least one of them must be selected from a liquid source. As the liquid, a polymer of alkoxysilane (mono-, di-, tri-, tetra-) and tetraalkoxysilane is used. Among alkoxysilanes, tetraalkoxysilane is preferably used, and specific examples include methoxysilane, ethoxysilane, propoxysilane, butoxysilane, and the like. From the viewpoint of handling, ethoxysilane is preferable. Examples of the tetraalkoxysilane polymer include a low molecular weight polymer (oligomer) having a degree of polymerization of about 2 to 15 and a silicate polymer having a higher degree of polymerization, which are liquid. Examples of solid materials that can be used in combination with these include silicon oxide. In the above reaction sintering method, silicon oxide includes silica gel (colloidal ultrafine silica-containing liquid, containing OH group or alkoxyl group inside), silicon dioxide (silica gel, fine silica, quartz powder), etc. in addition to SiO. . These silicon sources may be used alone or in combination of two or more.

Among these silicon sources, from the viewpoint of good homogeneity and handling properties, an oligomer of tetraethoxysilane, a mixture of an oligomer of tetraethoxysilane and fine powder silica, and the like are preferable. These silicon sources are high-purity substances, and the initial impurity content is preferably 20 ppm or less, more preferably 5 ppm or less.
The substance used as the carbon source is preferably a high-purity organic compound that contains oxygen in the molecule and remains carbon by heating. Specific examples include various sugars such as phenol resin, furan resin, epoxy resin, phenoxy resin, monosaccharides such as glucose, oligosaccharides such as sucrose, polysaccharides such as cellulose and starch. For the purpose of homogeneously mixing with the silicon source, these are mainly used in liquid form at room temperature, those that dissolve in a solvent, those that soften or become liquid when heated, such as thermoplasticity or heat melting properties. It is done. Of these, resol type phenol resins and novolac type phenol resins are preferred. In particular, a resol type phenol resin is preferably used.

  The polymerization and crosslinking catalyst used in the production of high-purity silicon carbide powder can be appropriately selected according to the carbon source. When the carbon source is a phenol resin or a furan resin, toluenesulfonic acid, toluenecarboxylic acid, acetic acid, oxalic acid And acids such as sulfuric acid. Among these, toluenesulfonic acid is preferably used.

  From the above, as a method for obtaining particularly high purity silicon carbide powder, the raw material powder production method described in the method for producing a single crystal in Japanese Patent Application Laid-Open No. 9-48605 previously filed by the applicant of the present application can be mentioned. That is, one or more selected from high-purity tetraalkoxysilane and tetraalkoxysilane polymer is used as a silicon source, and a high-purity organic compound that generates carbon by heating is used as a carbon source. A silicon carbide production step for obtaining a silicon carbide powder by heating and firing the obtained mixture in a non-oxidizing atmosphere; and maintaining the obtained silicon carbide powder at a temperature of 1700 ° C. or higher and lower than 2000 ° C. A post-treatment step of performing at least one heat treatment at a temperature of 2000 ° C. to 2100 ° C. for 5 to 20 minutes, and the content of each impurity element is 0.5 ppm or less by performing the above two steps. A method for producing a high-purity silicon carbide powder for obtaining a silicon carbide powder can be used. Since the silicon carbide powder obtained in this manner is non-uniform in size, it is preferable to treat the silicon carbide powder so as to meet the above particle size by pulverization and classification.

  In the case of introducing nitrogen in the process of producing silicon carbide powder, first, a silicon source, a carbon source, an organic substance composed of a nitrogen source, and a polymerization or crosslinking catalyst are homogeneously mixed. When dissolving an organic substance composed of a carbon source such as hexamethylenetetramine and a polymerization or crosslinking catalyst such as toluenesulfonic acid in a solvent such as ethanol, a silicon source such as an oligomer of tetraethoxysilane And thoroughly mixed. Moreover, when manufacturing silicon carbide powder, it is preferable to calcinate in a nitrogen atmosphere to dissolve a large amount of nitrogen. The silicon carbide fine powder is conveniently a β-type silicon carbide powder having a nitrogen content of 0.1% by volume or more. This is because electric discharge machining can be performed on the silicon carbide sintered body and the workability is improved.

  Next, the nonmetallic sintering aid will be described. The silicon carbide sintered body according to this embodiment has a free carbon content of 2 to 10% by weight. This free carbon is attributed to the organic material used for the nonmetallic sintering aid, and the amount of free carbon is adjusted to the above-mentioned range by adjusting the addition conditions such as the addition amount of the nonmetallic sintering aid. Can be.

  As the non-metallic sintering aid, those containing an organic material that can be a free carbon source as described above, that is, carbon that is generated by heating (hereinafter sometimes referred to as “carbon source”) are used. The above-mentioned organic material alone or a material obtained by coating the above-mentioned organic material on the surface of silicon carbide powder (particle size: about 0.01 to 1 micron) may be used as a sintering aid. Therefore, it is preferable to use an organic material alone. Specific examples of organic materials that generate carbon by heating include coal tar pitch, pitch tar, phenol resin, furan resin, epoxy resin, phenoxy resin, and various sugars such as glucose, which have a high residual carbonization rate. Examples thereof include small sugars such as monosaccharides and sucrose, and polysaccharides such as cellulose and starch. In order to uniformly mix the organic material with the silicon carbide powder, the organic material is preferably liquid at room temperature, dissolved in a solvent, or softened by heating such as thermoplasticity and heat melting. Among these, the use of a phenol resin is preferable because the strength of the silicon carbide sintered body is improved, and a resol type phenol resin is more preferable. Although the action mechanism of these organic materials is not clear, when the organic materials are heated, inorganic carbon compounds such as carbon black and graphite are produced in the system. It is considered that this inorganic carbon-based compound acts effectively as a sintering aid. However, the same effect cannot be obtained even if carbon black or the like is used as a sintering aid.

  The nonmetallic sintering aid may be dissolved in an organic solvent if desired, and the solution and silicon carbide powder may be mixed. The organic solvent to be used varies depending on the nonmetallic sintering aid. For example, when a phenol resin is used as the sintering aid, lower alcohols such as ethyl alcohol, ethyl ether, acetone, or the like can be selected. When producing a high-purity silicon carbide sintered body, it is preferable to use not only a high-purity silicon carbide powder but also a sintering aid and an organic solvent having a low impurity content.

The addition amount of the nonmetallic sintering aid to the silicon carbide powder is determined so that the free carbon of the silicon carbide sintered body is 2 to 10% by weight. If the free carbon is outside this range, the chemical change to SiC that progresses during the bonding process, and the bonding between the silicon carbide sintered bodies becomes insufficient. Here, the content (% by weight) of free carbon is determined by heating the silicon carbide sintered body at 800 ° C. for 8 minutes in an oxygen atmosphere, and measuring the amount of generated CO ₂ and CO with a carbon analyzer. It can be calculated from the measured value. The amount of sintering aid added varies depending on the type of sintering aid used and the amount of surface silica (silicon oxide) in the silicon carbide powder. As a guideline for determining the addition amount, the surface silica (silicon oxide) content of the silicon carbide powder is quantified in advance using hydrogen fluoride water, and the stoichiometry sufficient to reduce the silicon oxide (formula (I)) The stoichiometry calculated in (1) is calculated. In consideration of this and the ratio of the nonmetallic sintering aid to generate carbon by heating, the amount added can be determined so that the free carbon falls within the above-mentioned suitable range. The description of the non-metallic sintering aid for the silicon carbide sintered body described above is described in more detail in the specification of Japanese Patent Application No. 9-041048.

  Examples of the solvent include water, lower alcohols such as ethyl alcohol, ethyl ether, and acetone. It is preferable to use a solvent having a low impurity content. Examples of antifoaming agents include silicone antifoaming agents. Further, an organic binder may be added as a binder when producing a slurry-like mixed powder from silicon carbide powder. Examples of the organic binder include polymer emulsion latex and the like, and the peptizer is preferably a nitrogen-based compound from the viewpoint of further enhancing the effect of imparting conductivity, such as ammonia and ammonium polyacrylate. Used. As the powder pressure-sensitive adhesive, polyvinyl alcohol urethane resin (for example, water-soluble polyurethane) is preferably used.

(Method for producing a silicon carbide sintered sheet)
The manufacturing method of the silicon carbide sintered compact sheet concerning embodiment uses (1) the process of obtaining the slurry-like mixed powder containing a silicon carbide powder and a nonmetallic sintering auxiliary agent, and (2) tape casting method. A step of forming a sheet-like temporary molded product from a silicon carbide slurry, and (3) a step of obtaining a silicon carbide sintered body sheet by hot press sintering in a state where the sheet-like temporary molded product is sandwiched between carbon spacers, 4) heating the composite of the silicon carbide sintered body sheet and the carbon spacer in an oxidizing atmosphere to burn off the carbon spacer. Hereinafter, each process will be described in detail.

(1) Step of obtaining mixed powder First, a silicon carbide powder and a nonmetallic sintering aid are dispersed in a solvent to prepare a slurry-like mixed powder. It is preferable to use a beta type as the silicon carbide powder, and it is preferable to use a phenol resin as the nonmetallic sintering aid. It is preferable to use ethanol as the solvent. The mixing ratio of the mixed powder is preferably 10 to 20 parts by weight of phenol resin with respect to 100 parts by weight of β-type silicon carbide fine powder (SiC). The solvent is preferably added in an amount of about 100 parts by weight per 100 parts by weight of β-type silicon carbide fine powder (SiC). Further, a plasticizer or a binder may be added to the mixed powder. Dioctyl phthalate is preferably used as the plasticizer. As the binder, polyvinyl butyral is preferably used. The plasticizer is preferably added in an amount of 2 to 5 parts by weight with respect to 100 parts by weight of the β-type silicon carbide fine powder. The binder is preferably added in an amount of 4 to 10 parts by weight with respect to 100 parts by weight of the β-type silicon carbide fine powder.
Next, stirring and mixing are performed for 6 hours to 48 hours, particularly 12 hours to 24 hours using a stirring and mixing means such as a mixer or a planetary ball mill. This is because if the stirring and mixing are not sufficiently performed, the nonmetallic sintering aid, the plasticizer, and the binder are not uniformly dispersed in the temporary molded body.

(2) Step of obtaining a sheet-like temporary molded product A sheet-like temporary molded product is formed from a silicon carbide slurry using a tape casting method. The thickness of the sheet-like temporary molded product is preferably 240 μm or less, and more preferably 50 to 100 μm. This is because if it is too thick, the sheet will crack during drying.

(3) Step of obtaining a silicon carbide sintered body sheet (A) A sheet-shaped temporary molded product is filled in a carbon spacer and filled in a molding mold and subjected to hot press sintering. Specifically, the sheet-like temporary molded product is put in a molding mold in a state of being sandwiched between carbon spacers, and hot press sintering is performed at a surface pressure of 300 to 700 kgf / cm ² . The hot pressing temperature is preferably 2000 ° C. to 2400 ° C. It is preferable to raise the temperature up to the maximum temperature gently and stepwise. When the temperature is increased in this way, chemical changes, state changes, and the like that occur at each temperature can be sufficiently advanced. As a result, it is possible to prevent impurities from being mixed, cracks and vacancies.

(B) An example of a preferred temperature raising step is shown below. First, a molding mold containing a sheet-like temporary molded product is placed in a heating furnace, and the inside of the furnace is brought to a vacuum state of 10 ⁻⁴ torr. Gently raise the temperature from room temperature to 200 ° C. and keep it at 200 ° C. for about 30 minutes. Thereafter, the temperature is raised to 700 ° C. in 6 to 10 hours and maintained at 700 ° C. for 2 to 5 hours. In the temperature raising process from room temperature to 700 ° C., desorption of adsorbed moisture and organic solvent occurs, and carbonization of the nonmetallic sintering aid proceeds. The holding time at the constant temperature varies depending on the size of the silicon carbide sintered body, and may be set to a suitable time as appropriate. In addition, the determination of whether the holding time is sufficient can be based on the time point when the decrease in the degree of vacuum is reduced to some extent. Next, the temperature is raised from 700 ° C. to 1500 ° C. in 6 to 9 hours, and held at 1500 ° C. for about 1 to 5 hours. While the temperature is maintained at 1500 ° C., a reaction in which silicon oxide is reduced to silicon carbide proceeds (formula (I): SiO ₂ + 3C → SiC + 2CO). Insufficient holding time is not preferable because silicon dioxide remains and adheres to the surface of the silicon carbide powder, preventing densification of the particles and causing large grains to grow. The determination as to whether or not the holding time is sufficient is based on whether or not the generation of carbon monoxide as a by-product is stopped, that is, the reduction of the vacuum degree is stopped, and the reduction reaction start temperature is 1300 ° C. It can be used as a guide whether the vacuum has been recovered.

(C) It is preferable to perform hot pressing after raising the temperature in the furnace to about 1500 ° C. at which sintering starts, and then filling with an inert gas in order to make the inside of the furnace a non-oxidizing atmosphere. Nitrogen gas or argon gas is used as the inert gas, but it is preferable to use argon gas that is non-reactive even at high temperatures. When it is desired to produce a high purity silicon carbide sintered body, an inert gas having a high purity is used. After making the inside of the furnace a non-oxidizing atmosphere, the inside of the furnace is heated and pressurized so that the temperature becomes 2000 ° C. to 2400 ° C. and the pressure becomes 300 to 700 kgf / cm ² . If the maximum temperature is less than 2000 ° C., densification is insufficient. On the other hand, if the maximum temperature exceeds 2400 ° C., there is a possibility that the powder or the molded body raw material may be sublimated (decomposed). It is preferable to raise the temperature from about 1500 ° C. to the maximum temperature over 2 to 4 hours and hold at the maximum temperature for 1 to 8 hours. Sintering proceeds rapidly at 1850-1900 ° C. and is completed during the maximum temperature holding time. The pressurization condition, insufficient is the density is less than 300 kgf / cm ^2, sometimes graphite of the mold exceeds 700 kgf / cm ² is damaged, the manufacturing efficiency is not preferable. The surface roughness (Ra) is preferably 0.5 μm or less, and more preferably 0.2 μm or less. In order to suppress the pressure grows abnormal grain, preferably pressurized with 300kgf / cm ² ~700kgf / cm ² approximately.

(4) Step of burning carbon spacers A composite of a silicon carbide sintered body and a carbon spacer is heated in an oxidizing atmosphere to burn the carbon spacers. The composite of the silicon carbide sintered body sheet and the carbon spacer is heated at 500 ° C. to 1200 ° C. for 2 to 24 hours in an oxidizing atmosphere to burn out the carbon spacer.

  According to the method for manufacturing a silicon carbide sintered body sheet according to the present embodiment, since a non-metallic sintering aid is used as a sintering aid, compared to when a metallic sintering aid is used. Thus, a high purity silicon carbide sintered body sheet is obtained. Moreover, a silicon carbide sintered body sheet having no warpage and stable dimensions can be obtained. Furthermore, a silicon carbide sintered body sheet that is optimal as a heater and has low temperature dependence of resistance is obtained.

[Silicon carbide sintered sheet]
The main characteristics of the silicon carbide sintered body sheet according to this embodiment are listed below. In addition, the silicon carbide sintered body sheet according to the present embodiment is preferably obtained by the method for producing a silicon carbide sintered body sheet.
The thickness is 240 μm or less, preferably 100 μm to 200 μm. Bulk density 3.10 g / cm ³ or more, preferably 3.15 g / cm ³ or more, more preferably 3.16 g / cm ³ or more. The volume resistivity at room temperature is 1 × 10 ⁰ Ω · m or less, preferably 1 × 10 ⁻¹ Ω · m or less. Moreover, B / A is 0.2-2 when the volume low efficiency in normal temperature is set to A, and the volume resistivity to 100-1000 degreeC is set to B. Because of such physical properties, the problem of temperature dependence can be greatly improved.
The total content of impurity elements in the silicon carbide sintered sheet (elements with atomic number 3 or more excluding C, N, O, Si in the periodic table of the 1989 IUPAC inorganic chemical nomenclature revised edition) is preferably 5 ppm or less, more preferably 3 ppm or less, particularly preferably 1 ppm or less. Since it has such characteristics, the silicon carbide sintered body sheet can be suitably used as a ceramic heater. When used as a ceramic heater, it is possible to save space and increase the purity in the heating atmosphere.

  The porosity is 1% to 32%, preferably 5% to 29%. Further, the resistance at 100 ° C. is 0.02 Ωcm to 0.06 Ωcm, preferably 0.03 Ωcm to 0.05 Ωcm. When the resistance at 100 ° C. is A and the resistance at 1000 ° C. is B, B / A = 0 .2-2. Because of such physical properties, the problem of temperature dependence can be greatly improved.

  The nitrogen content of the silicon carbide sintered body sheet according to the present embodiment is 500 ppm or more, preferably 500 ppm to 1200 ppm, more preferably 550 ppm to 900 ppm. Therefore, since it has conductivity, it can be processed into a complicated shape by an electric discharge machining method. Moreover, since it is thin, it can be processed into a complicated shape by a laser processing method. For example, the heater is manufactured by forming a spiral or concentric groove in the molded body.

(Modification of the embodiment)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. For example, in the said embodiment, the method of obtaining a silicon carbide sintered compact sheet from one sheet-like temporary molded product was disclosed. However, in the step of (3) obtaining a silicon carbide sintered body sheet, the thickness of the silicon carbide sintered body sheet can be finally adjusted by overlapping a plurality of sheet-like temporary molded products. As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

Examples of the present invention are shown below, but the present invention is not limited to these examples at all:
(Example)
High-purity β-type silicon carbide powder having a center particle diameter of 2 μm (contains silicon carbide having an impurity content of 5 ppm or less produced according to the production method described in JP-A-9-48605 / 1.5% by weight of silica) 100 After adding 13.6 parts by weight of phenol resin, 3.2 parts by weight of dioctyl phthalate, and 6.4 parts by weight of polyvinyl butyral to 100 parts by weight of ethanol as a solvent, the mixture is stirred for 24 hours using a ball mill. Thus, a slurry-like mixed powder was obtained.
The obtained slurry-like mixed powder was tape-cast using an applicator, dried at room temperature, cut out to a diameter of 30 mm, and a sheet-like molded body having a diameter of 30 mm and a thickness of 90 μm was obtained. After stacking one to a plurality of the obtained sheet-like molded bodies, hot press sintering was performed in a state where the sheet-like temporary molded product was sandwiched between carbon spacers having a density of 1.8 g / cm ³ and a thickness of 1 mm. . Hot press sintering was performed under a vacuum condition of 10 ⁻⁶ to 10 ⁻⁴ torr at a pressure of 500 kg / cm ³ and heated from room temperature to 1500 ° C. in 5 hours. Further, pressurization was performed at a pressure of 500 kg / cm ³ under an argon atmosphere of 100 to 105 kPA, the temperature was increased from 1500 ° C. to 2300 ° C. over 3 hours, and the temperature was maintained at 2300 ° C. for 2 hours. Then, it cooled to room temperature under argon atmosphere.
The silicon carbide sintered sheet and the carbon spacer after hot press sintering were heated at 1000 ° C. for 4 hours in an oxidizing atmosphere to burn the carbon spacer. And the silicon carbide sintered compact sheet | seat of 30 micrometers, 120 micrometers, and 240 micrometers thickness was obtained.

The bulk density of each silicon carbide sintered body sheet was 3.16 g / cm ³ . The volume resistivity at room temperature was 5 × 10 ⁻² Ω · m. Moreover, the numerical value of B / A when the volume low efficiency in normal temperature was set to A and the volume resistivity to 100-1000 degreeC was set to B was 0.6 at 500 degreeC, and 0.5 at 1000 degreeC. The flatness was 0.03 mm. The impurity concentration is 0.02 ppm for B, 0.01 ppm or less for Na, 0.08 ppm for Al, 0.01 ppm or less for K, 0.02 ppm for Ti, 0.02 ppm for Cr, 0.02 ppm for Mg, and 0 for Fe. 0.05 ppm or less, Co 0.01 ppm or less, Ni 0.01 ppm or less, Cu 0.04 ppm, Zn 0.01 ppm, and W 0.01 ppm or less.

  According to the examples, since a non-metallic sintering aid is used as a sintering aid, a high-purity silicon carbide sintered body sheet can be obtained as compared with the case where a metallic sintering aid is used. can get. Moreover, a silicon carbide sintered body sheet having no warpage and stable dimensions can be obtained. Furthermore, a silicon carbide sintered body sheet having a low temperature dependency of the optimum resistance as a heater can be obtained.

Claims (9)

Obtaining a slurry-like mixed powder containing silicon carbide powder and a nonmetallic sintering aid;
Forming a sheet-like temporary molded product from the silicon carbide slurry using a tape casting method;
A step of obtaining a silicon carbide sintered body sheet by hot press sintering in a state where the sheet-like temporary molded product is sandwiched between carbon spacers;
The manufacturing method of the silicon carbide sintered compact sheet characterized by including this.   The silicon carbide sintered body according to claim 1, further comprising a step of heating the composite of the silicon carbide sintered body sheet and the carbon spacer in an oxidizing atmosphere to burn off the carbon spacer. Sheet manufacturing method.   The method for producing a silicon carbide sintered body sheet according to claim 1 or 2, wherein the non-metallic sintering aid is a phenol resin.   The said plasticizer is a dioctyl phthalate, The manufacturing method of the silicon carbide sintered compact sheet in any one of Claims 1-3 characterized by the above-mentioned.   The said silicon carbide slurry contains polyvinyl butyral as a binder further, The manufacturing method of the silicon carbide sintered compact sheet in any one of Claims 1-4 characterized by the above-mentioned.   6. The silicon carbide sintered body sheet is obtained by hot press sintering in a state where a plurality of the sheet-like temporary molded products laminated are sandwiched between the carbon spacers. 6. Of manufacturing a silicon carbide sintered body sheet.   The method for producing a sintered silicon carbide sheet according to any one of claims 1 to 6, wherein the slurry further contains a binder.   The said slurry further contains a plasticizer, The manufacturing method of the silicon carbide sintered compact sheet in any one of Claims 1-7 characterized by the above-mentioned. A silicon carbide sintered body sheet having a thickness of 240 μm or less and a bulk density of 3.15 g / cm ³ or more.