JP2000119064A - SiC FORM AND ITS PRODUCTION - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a SiC form of low light transmittance, suitably usable as one of various heat-resistant members including various members for semiconductor manufacture such as shields and dummy wafers, and to provide a method for producing the SiC form. SOLUTION: This SiC form is a CVD-SiC form obtained by CVD method, being such one that at least one visible light-opaque CVD-SiC layer 2-20 μm thick is formed on the surface or inside thereof and the light transmittance over a wavelength range of 200-2,500 nm is <=0.4%. The method for producing the SiC form comprises forming a SiC coating film on a substrate by CVD reaction followed by removing the substrate; wherein during the SiC coating film formation process, CVD reaction conditions set in advance are altered to form at least one visible light-opaque CVD-SiC layer on the surface or inside of the SiC form; alternatively, using the above-mentioned CVD-SiC form as a substrate, during forming a SiC coating film on the surface of the substrate, CVD reaction conditions set in advance are altered to form at least one visible light-opaque CVD-SiC layer on the surface or inside of the SiC form.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various heat-resistant members such as shields for heat treatment equipment of semiconductor manufacturing equipment, heat equalizing rings, etc. Also, the present invention relates to a SiC molded body that can be suitably used as various members such as a dummy wafer and a susceptor used in a diffusion furnace apparatus, an etching apparatus, a CVD apparatus, and the like of a semiconductor manufacturing apparatus, and a method of manufacturing the same.

[0002]

2. Description of the Related Art SiC has excellent material properties such as heat resistance, corrosion resistance and strength properties, and is useful as various industrial members. In particular, a SiC molded body (CVD-SiC molded body) manufactured using a CVD method (chemical vapor deposition method).
Because of its high density and high purity, it is suitably used in various application fields requiring high purity, including various members for semiconductor production.

[0003] In this CVD-SiC compact, a raw material gas is subjected to a gas phase reaction to precipitate crystal grains of SiC on a substrate surface,
It is obtained by forming a film by growing crystal grains and then removing the substrate, and is characterized by a dense material, high purity, and high texture homogeneity.

[0004] As a SiC molded body by the CVD method, for example, Japanese Patent Application Laid-Open No. 6-239609 discloses a self-supporting β-SiC deposited by chemical vapor deposition having an attenuation constant of about 20 cm ^-1 or less at 0.6328 microns. Free standing β-SiC deposited by chemical vapor deposition with an attenuation constant of less than about 20 cm ^{−1 at} 3 microns has been proposed. S by this CVD method
It is known that the higher the purity, the higher the light transmittance of the obtained SiC is, and the iC molded body has a theoretical density of 100% and high purity, that is, a metal impurity of 5 ppm or less, preferably about 3.5 ppm or less. Are disclosed as metal impurities.

However, such high-purity CVD
Since the SiC formed body by the method has light transmittance,
When the C compact is used as various members such as a semiconductor manufacturing apparatus and a heat treatment apparatus, the physical properties of SiC may become a problem depending on the application field. For example, rapid thermal annealing is used in semiconductor manufacturing processes.
ealing), rapid thermal cleanin
g), rapid thermal chemical vapor deposition
por deposition), rapid thermal oxidation
n), rapid thermal nitridation (rapid thermal nitridation) and other rapid heat treatment processes (called RTP). Japanese Unexamined Patent Application Publication No. 9-237789 discloses that a wafer substrate has excellent in-plane uniformity even by high-speed heating. It has been proposed that the shield be made of SiC to exhibit,
Material properties that are opaque to radiant heat are required.

In this RTP, precise temperature control of the wafer substrate is required. However, when measuring the temperature with a pyrometer, when forming a black body cavity on the surface opposite to the processing surface of the wafer substrate, the wafer is not heated. If light is transmitted through a member or the like that supports the substrate, there is a problem that disturbance light is generated and accurate temperature control becomes difficult. Therefore, Japanese Patent Application Laid-Open No. 8-25580
No. 0 proposes that a support ring for supporting a wafer substrate is made of silicon or silicon oxide, and a cylinder for holding the support ring is made of quartz coated with silicon so as to be opaque in the frequency range of a pyrometer. .

Further, in Japanese Patent Application Laid-Open No. 6-341905, in order to prevent light leaking from the heating element from entering the reflection cavity, a partition wall and a guard ring supporting the wafer are arranged along the wafer. It has been proposed that this guard ring be made of silicon, having a black or gray color that absorbs light leaking from the heating element. But,
JP-A-6-341905 and JP-A-8-25580
In the case of silicon or the one coated with silicon disclosed in Japanese Patent Publication No. 0, there is a problem that the corrosion resistance against acid washing for repeated use is poor, the thickness of the coated silicon is reduced, and the light impermeability is reduced.

[0008] Further, a dummy wafer used for stabilizing the etching conditions of the wafer in the plasma etching process and a dummy wafer used for stabilizing the conditions of the wafer in the CVD process are required to have low light transmittance. The wafer is mounted on a support boat by a transfer robot, but the wafer is recognized by irradiating laser light, so if the light transmittance of the wafer is high, the robot can accurately recognize the position of the wafer. Therefore, it is difficult to mount a wafer at a predetermined position in the reaction apparatus.

Conventionally, the crystal form of a CVD-SiC compact is β-type, and in the case of high purity, it exhibits a yellow color and has light transmittance, so that it has been difficult to reduce the light transmittance. For example, there is a method of roughening the surface as a means for lowering light transmittance by scattering light on the surface.
When irradiated with light having a surface roughness of 10 nm or less, the surface roughness Ra having a specular property of 10 nm or less exhibits a transmittance of 40 to 60%.
Although the light transmittance is reduced by exhibiting a transmittance of 0.8%, it is difficult to provide satisfactory light opacity in a wide wavelength range.

[0010]

The inventors of the present invention have studied the relationship between the properties of the CVD-SiC molded product and the optical characteristics. As a result, there is a layer that scatters and reflects light as a material structure of the SiC molded product. Then, they found that the light transmittance can be lowered. The present invention has been developed based on this finding, and its object is to provide a high purity, excellent heat resistance and strength characteristic, and particularly excellent light opacity, for example, various members for semiconductor manufacturing such as a shield and a dummy wafer. Another object of the present invention is to provide a CVD-SiC molded body composed of a β-type crystal with high purity, which can be suitably used as various heat-resistant members for a heat treatment apparatus, and a method for producing the same.

[0011]

The SiC compact according to the present invention for achieving the above object is a CVD-SiC compact comprising a β-type crystal obtained by a CVD method,
At least one visible light-impermeable CVD-SiC layer having a thickness of 2 to 20 μm is formed on the surface or inside thereof, and the light transmittance in a wavelength region of 300 to 2500 nm is 0.4% or less. This is a structural feature.

[0012] The method for producing a SiC molded body according to the present invention comprises:
In a method for producing a SiC molded body, a SiC film is formed on a substrate surface by a CVD reaction and then the substrate is removed. The SiC layer is formed by CVD-
It is characterized in that at least one layer is formed on the surface or inside of the SiC molded body.

[0013] Another method for producing a SiC molded article of the present invention is to form a CVD-SiC molded article obtained by forming a SiC film on a substrate surface by a CVD reaction and then removing the substrate, In the process of forming the SiC film on the material surface, the setting of the CVD reaction conditions is changed to form at least one visible light opaque CVD-SiC layer on the surface or inside the CVD-SiC molded body. The feature of.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in the sectional view of FIG.
In the upper layer of the VD-SiC base material 2, a visible light opaque CV
D-SiC layer 3, visible-light-transmitting CVD-S on the upper layer
The iC layer 4 has a three-layer structure in which layers are sequentially formed. FIG. 1 shows the inside of a CVD-
This is an example in which one SiC layer 3 is formed. FIG. 2 illustrates a cross-sectional view of a SiC molded body in which two visible light-impermeable CVD-SiC layers 3 are formed.

SiC is deposited by the CVD method and S
In the process of forming the iC film, first, a raw material gas undergoes a gas-phase reaction to generate nuclei of SiC on the substrate surface, and the SiC nuclei grow to become amorphous SiC, and finer polycrystalline SiC particles are formed. Continues to grow into a columnar crystal structure through S
An iC coating is formed. Therefore, the properties of the CVD-SiC molded body, such as the strength characteristics, thermal characteristics, and optical characteristics, differ depending on the particle characteristics of the SiC film formed by deposition on the substrate surface.

For example, when light passes from a SiC layer having a large particle diameter to a SiC layer having a small particle diameter, complicated scattering, refraction, reflection, and the like of light occur at the interface, confining the light and reducing the light transmittance. . In addition, SiC with small particle size
Similarly, when light passes from the layer to the SiC layer having a large particle diameter, the light transmittance also decreases. The SiC molded article of the present invention is characterized by forming at least one layer of visible light impervious CVD-SiC layer composed of fine particles of submicron order on the surface or inside of the CVD-SiC molded article. Light transmittance such as scattering, refraction, reflection and the like is changed to obtain a low light transmittance. That is, by providing the visible light opaque CVD-SiC layer having different particle properties, the crystal structure is disturbed, and the light transmittance is reduced.

The visible light opaque CVD-SiC layer not only has a large effect of attenuating the light transmittance in the wavelength range of 380 to 780 nm, which is the wavelength range of visible light, but also has a near-infrared light to infrared light exceeding 780 nm. The effect of attenuating the light transmittance in the wavelength range is also large. As a result, specifically, 300 to 2500 nm
Having a small light transmittance in the wavelength range from visible light to infrared light, having a light transmittance of 0.4% or less in the wavelength range of
A molded article can be provided. When two or more layers of the visible light opaque CVD-SiC layer 3 are formed, 300 to 300
The light transmittance in the wavelength region of 2500 nm can be further reduced. For example, by forming at least two layers, a SiC molded body having a low transmittance of 0.2% or less can be obtained.

The thickness of the visible light opaque CVD-SiC layer is set in the range of 2 to 20 μm.
When the thickness of one layer is less than 2 μm, the effect of lowering the light transmittance is small. On the other hand, when the thickness of one layer is large, peeling due to thermal shock tends to occur. You. Further, the thickness of the CVD-SiC molded body is preferably 400 μm or more in order to maintain strength and physical property stability as a CVD-SiC free-standing molded body.

The SiC molded article of the present invention is characterized in that
C for forming a SiC film by reaction and then removing the substrate
In the method of manufacturing a VD-SiC molded body, at least one visible light opaque CVD-SiC layer is formed on the surface or inside of the CVD-SiC molded body by changing the setting of the CVD reaction conditions in the process of forming the SiC coating. It can be manufactured by forming a layer.

In this manufacturing method, as shown in the process diagram illustrated in FIG. 3, the CVD reaction conditions are appropriately set in the process of depositing SiC in a vapor phase on a removable substrate surface by CVD reaction to form a SiC film. Alternately, visible light impervious CVD-SiC consisting of submicron class fine particles in SiC coating
After forming at least one layer, the substrate is removed.

As the removable substrate, a carbon-based material, a metal-based material such as silicon, quartz, or the like is used. The carbon-based material has good workability and can be easily burned and removed by heat treatment in air. Particularly, a graphite material is preferably used. The graphite material preferably has a high purity with as little impurities as possible. The method of removing the substrate after forming the SiC film is as follows.
Cutting removal, polishing removal, combustion removal by heating in air, or a combination thereof can be performed as appropriate.

In the CVD reaction, for example, a graphite substrate was set in a reaction furnace, the air in the system was evacuated, heated and maintained at a predetermined temperature, and then a hydrogen gas was fed in to replace the atmosphere with a normal pressure hydrogen gas atmosphere. After that, a hydrogen gas is used as a carrier gas, and a halogenated organosilicon compound such as trichloromethylsilane, trichlorophenylsilane, dichloromethylsilane, or dichlorodimethylsilane is supplied as a source gas, and SiC is deposited by a gas phase thermal decomposition reaction. Then, an SiC coating is applied to the graphite substrate surface. The reaction temperature for the gas phase thermal decomposition is desirably set in a temperature range of 1000 to 1450 ° C. in order to keep the strength and the thermal conductivity of the CVD-SiC molded body high.

In the process of forming the SiC film, a SiC nucleus is first generated on the substrate surface by a gas phase thermal decomposition reaction of a raw material gas, and the SiC nucleus grows into amorphous SiC.
It gradually grows into fine polycrystalline SiC grains. Further CVD
When the reaction is continued, the fine polycrystalline SiC grains continue to grow into a columnar crystal structure to form a SiC film. In this film forming process, the visible light opaque CVD-SiC layer is
For example, the mixing ratio of the halogenated organosilicon compound as the raw material gas and the hydrogen gas as the reducing agent, the flow rate of the mixed gas, the CV
D CV such as reaction temperature, reaction time, pressure of CVD reactor etc.
By appropriately setting and changing the D reaction conditions, a SiC layer composed of SiC particles having different particle properties can be formed.

Specifically, for example, as a method of changing the mixing ratio of the halogenated organosilicon compound as the raw material gas and the hydrogen gas as the reducing agent, the partial pressure of the hydrogen gas in the reactor is set to 10 to 300 mmHg / As a method of gradually decreasing or increasing at a rate of minute, a method of changing a CVD reaction temperature, a method of raising or lowering the temperature of a substrate at a rate of 1 to 20 ° C./minute, and a method of changing a pressure of a CVD reaction apparatus The visible light-impermeable CVD-SiC layer can be formed by performing a method of gradually increasing the total pressure in the reaction furnace at a rate of 10 to 50 mmHg / min alone or in combination.

Next, the CVD reaction conditions such as the mixing ratio of the halogenated organosilicon compound as the raw material gas and the hydrogen gas as the reducing agent, the flow rate of the mixed gas, the CVD reaction temperature and the reaction time, and the pressure of the CVD reactor are fixed. When held at
The structure of the coating is a crystal having a columnar structure of SiC particles, and a visible light transmitting CVD-SiC layer is formed.

Therefore, the visible light opaque CVD-Si
If the C layer and the visible light-transmitting CVD-SiC layer are alternately and repeatedly formed, a desired number of visible light-impermeable CVD-layers may be formed on the surface or inside the CVD-SiC molded body.
An SiC layer can be formed.

After forming the SiC film having at least one visible light opaque CVD-SiC layer on the surface of the substrate in this manner, the substrate is removed by cutting, polishing, removing by heating in air, and burning. Alternatively, they are removed by a method in which these are appropriately combined, and the SiC molded body of the present invention is manufactured.

Further, the SiC molded article of the present invention uses a CVD-SiC molded article obtained by forming a SiC film on a substrate surface by a CVD reaction and then removing the substrate, using the SiC film on the substrate surface. In the process of forming a film, the CVD reaction conditions are changed and the visible light-impermeable CVD-SiC layer is
It can also be manufactured by a method of forming at least one layer on the surface or inside of the SiC molded body.

In this manufacturing method, as shown in the process diagram illustrated in FIG. 4, S
The iC was vapor-phase deposited to form a SiC film, and then the substrate was removed to obtain a CVD-SiC molded body as a substrate. Visible light opaque CV composed of different SiC particles
At least one D-SiC layer is formed on the surface or inside of the CVD-SiC molded body.

In this manufacturing method as well, other manufacturing conditions can be applied as they are, such as changing the setting of the CVD reaction conditions applied to the method illustrated in the process chart of FIG. CVD-
Visible light opaque C on the surface or inside of SiC molded body
At least one VD-SiC layer can be formed. That is, the manufacturing method illustrated in FIG.
CVD-C obtained by forming a C film and then removing the substrate
In the process of forming a SiC film on the surface of a SiC molded body, the CVD reaction conditions are changed in the process of forming a SiC film on the surface to form a visible light opaque CVD-SiC layer. The method comprises forming a visible light-impermeable CVD-SiC layer in the process of forming a SiC film on a substrate, and then removing the substrate. The same means is applied to the method and conditions for forming the SiC layer.

In the measurement of the light-impermeable layer and the light-transmitting layer of the SiC molded body of the present invention, the SiC molded body is cut at right angles to the laminating surface direction by a diamond cutter or the like, and has a thickness of 0.1 to 0.1 mm.
The sample is ground and polished to a thickness of 0.15 mm to obtain a specular surface, and the sample is used to observe transmitted light with a white light source using a tungsten filament.

The transmittance of the SiC molded body is 5 mm in thickness.
The light transmittance is measured by using a self-recording spectrophotometer manufactured by Shimadzu Corporation using the metal aluminum plate as a standard sample, and is calculated by the following equation. T = BA Here, T: transmittance of SiC molded body A: measured value of light transmittance of metal aluminum plate B: measured value of light transmittance of SiC molded body

The SiC molded body thus manufactured is
All of the crystal forms are of the β type, have a density of 3.2 g / cm ³ or more, a thermal conductivity of 220 W / mK or more, and a thermal expansion coefficient of 3.9 or more.
It exhibits properties such as 4.5 × 10 ^-8 / K (room temperature to 1000 ° C.), is stable even when irradiated with high-energy irradiation light, and has a very small content of metal impurities. The amount is 1 ppm or less, and the analysis value by total reflection X-ray fluorescence is 1 × 10 ¹⁰ atom / cm ² or less. Therefore, it is possible to obtain a SiC molded body having high purity, excellent heat resistance and strength characteristics, and extremely low light transmittance.

[0034]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples.

Comparative Example Bulk density 1.8 g / cm ³ , coefficient of thermal expansion 4.3 × 10 ⁻⁶ / K,
An isotropic graphite material having an ash content of 20 ppm or less was processed to a diameter of 202 mm and a thickness of 5 mm to prepare a substrate. This graphite substrate is CVD
After setting in a quartz reaction tube of a reaction apparatus and replacing the inside of the system with hydrogen gas, using trichloromethylsilane as a raw material gas and hydrogen gas as a carrier gas, the concentration of trichloromethylsilane in the mixed gas was 7.5. vol%, mixed gas 190
It was fed into the reaction tube at a flow rate of l / min. A CVD reaction was performed at a CVD reaction temperature of 1400 ° C. and a reaction time of 30 hours to form a SiC film on the graphite substrate surface. Then
After heating in air to burn off the graphite substrate, it was polished and smoothed to produce a disc-shaped SiC molded body having a diameter of 200 mm and a thickness of 0.5 mm. The density of this CVD-SiC molded body was 3.21 g / cm ³ , the thermal conductivity was 250 W / mK, and the thermal expansion coefficient was 4.6 × 10 ⁻⁶ / K (room temperature to 1000 ° C.).

Example 1 In the process of forming the SiC film of the comparative example, the CVD reaction temperature was lowered from 1400 ° C. to 1200 ° C. at a rate of 6 ° C./min, kept at 1200 ° C. for 1 hour, and then
The temperature was raised to 1400 ° C at a rate of ° C / min. This operation was continuously repeated twice, and the CVD reaction was performed for a total of 30 hours. By changing the setting of the CVD reaction conditions in this way, a visible light opaque CV having a thickness of 20 μm is internally formed.
An SiC film having two D-SiC layers was formed.
Thereafter, the graphite substrate was removed by the same method as the comparative example,
Polished disk-shaped Si 200mm in diameter and 0.5mm thick
A C compact was produced. The density of this CVD-SiC molded body was 3.21 g / cm ³ , the thermal conductivity was 230 W / mK, and the thermal expansion coefficient was 4.2 × 10 ⁻⁶ / K (room temperature to 1000 ° C.).

Example 2 In the process of forming the SiC film of the comparative example, the CVD reaction temperature was set to 1200 ° C., and the hydrogen gas partial pressure was set to 10 mm.
Hg / min reduced from 740mmHg to 680mmHg,
After maintaining the state for 0.5 hour, the pressure was increased again at a rate of 10 mmHg / min and returned to 740 mmHg. By changing the setting of the CVD reaction conditions in this way, the CV
D reaction was performed, and a 20 μm thick visible light impervious C
After forming a SiC film in which one VD-SiC layer was formed, the graphite substrate was removed and polished by the same method as in the comparative example to obtain a disc-shaped SiC molded body having a diameter of 200 mm and a thickness of 0.5 mm. Manufactured. The density of this CVD-SiC molded body was 3.21 g / cm ³ , the thermal conductivity was 220 W / mK, and the thermal expansion coefficient was 4.2 × 10 ⁻⁶ / K (room temperature to 1000 ° C.).

Example 3 In the process of forming the SiC film of the comparative example, the reaction temperature was set to 1200 ° C. as the CVD reaction conditions, and the total pressure in the CVD reaction tube was increased from 310 mmHg to 30 mmHg / min while increasing the pressure to 760 mmHg / min. To 0.5
After holding for a time, the pressure was reduced at a rate of 30 mmHg / min to 310.
The operation of returning to mmHg was performed twice. In this way, the CVD reaction conditions are changed, and the CVD reaction is performed for a total of 30 hours, and the visible light-impermeable CVD-S having a thickness of 20 μm is internally formed.
After forming an SiC film having two iC layers, the graphite substrate was removed and polished by the same method as in the comparative example to produce a disc-shaped SiC molded body having a diameter of 200 mm and a thickness of 0.5 mm. . The density of this CVD-SiC compact was 3.23 g.
/ cm ³ , thermal conductivity 240 W / mK, thermal expansion coefficient 4.3 × 1
0 ⁻⁶ / K (room temperature to 1000 ° C.).

The light transmittance of the thus produced SiC molded body was measured by using a self-recording spectrophotometer manufactured by Shimadzu Corporation. The obtained results are shown in Table 1.

[0040]

[Table 1]

According to the results shown in Table 1, by changing the CVD reaction conditions when forming the SiC film by the CVD method, the SiC layer made of SiC particles having different particle properties and not transmitting visible light can be used as the SiC molded body. The SiC molded body of the embodiment in which one or two layers are formed inside
Light transmittance in the wavelength range of 300 to 2500 nm is as small as about 0.15 to 0.3% or less, and excellent in light opacity in the wavelength range from visible light to infrared light, as compared with the C molded body. I understand.

[0042]

As described above, according to the present invention, CVD-
2-20μm thickness on surface or inside of SiC molded body
Since at least one visible-light-impermeable CVD-SiC layer is formed, the light-impermeable material in the wavelength range of visible light to infrared light of 300 to 2500 nm is excellent, and a dense, high-purity SiC molded body is formed. Is provided. Further, according to the manufacturing method, in the process of forming the SiC film by the CVD reaction, the visible light opaque CVD-SiC layer can be formed by changing the setting of the CVD reaction conditions.
Therefore, the present invention is extremely useful as a SiC molded body that can be suitably used as various heat-resistant members for a heat treatment apparatus, such as various members for manufacturing a semiconductor such as a shield and a dummy wafer, and a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a SiC molded body of the present invention in which one visible-light-impermeable CVD-SiC layer is formed.

FIG. 2 is a cross-sectional view illustrating a SiC molded body of the present invention in which two visible light opaque CVD-SiC layers are formed.

FIG. 3 is a flowchart showing a manufacturing process of the SiC molded body of the present invention.

FIG. 4 is a flowchart showing another manufacturing process of the SiC molded body of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 SiC molded object 2 CVD-SiC base material 3 Visible light opaque CVD-SiC layer 4 Visible light permeable CVD-SiC layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/68 H01L 21/68 NA (72) Inventor Toshihiro Kuroyanagi 1-2-3 Kitaaoyama, Minato-ku, Tokyo No. Tokai Carbon Co., Ltd. (72) Inventor Tadakazu Iwamura 1-3-2 Kitaaoyama, Minato-ku, Tokyo F-term in Tokai Carbon Co., Ltd. 4G001 BA77 BB22 BC22 BD03 BD05 BD31 BD38 BE03 BE11 BE32 4G046 MA15 MB03 MB08 MC02 4G052 DA02 DB12 DC09 4K030 AA06 AA17 BA37 BB04 EA03 FA10 JA09 JA10 LA01 LA11 5F031 CA11 DA13 EA01 MA28 MA29 MA32

Claims (7)

[Claims] 1. A CVD-SiC molded body comprising a β-type crystal obtained by a CVD method, wherein a visible light-impermeable CVD-Si having a thickness of 2 to 20 μm is formed on the surface or inside thereof.
At least one C layer is formed, and 300 to 250
A SiC molded body having a light transmittance of 0.4% or less in a wavelength range of 0 nm. 2. The thickness of a CVD-SiC compact is 400 μm.
The SiC molded body according to claim 1, which is not less than m. 3. A method for producing a CVD-SiC molded body, in which a SiC film is formed on a surface of a substrate by a CVD reaction and then the substrate is removed, the conditions of the CVD reaction are changed during the process of forming the SiC film, and visible light is changed. A method for producing a SiC molded body, comprising forming at least one impermeable CVD-SiC layer on the surface or inside of a CVD-SiC molded body. 4. A CVD-SiC formed body obtained by forming a SiC film on a substrate surface by a CVD reaction and then removing the substrate, and using the CVD-SiC formed body obtained as a base material in the process of forming the SiC film on the substrate surface. Change the conditions to set the visible light opaque CVD-
A method for producing a SiC molded body, comprising forming at least one SiC layer on the surface or inside of a CVD-SiC molded body. 5. The partial pressure of hydrogen gas in a reactor is 10 to 30.
C by decreasing or increasing at a rate of 0 mmHg / min
5. The method for producing a SiC molded body according to claim 3, wherein the VD reaction conditions are changed. 6. The temperature of a substrate or a substrate is 1 to 20 ° C. /
5. The setting of the CVD reaction condition is changed by heating while raising or lowering the temperature at a rate of minutes.
A method for producing a SiC molded body according to the above. 7. The method according to claim 3, wherein the CVD reaction conditions are changed by increasing the total pressure in the reactor at a rate of 10 to 50 mmHg / min.