JP2002003285A - SiC-COATED GRAPHITE MATERIAL AND ITS MANUFACTURING METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon carbide-coated graphite material that has excellent thermal shock resistance and corrosion resistance, and, for example, is suitable for a material for a heat treatment in semiconductor production due to a SiC film separated in a gas phase by CVD method which is firmly coated on the surface of a graphite substrate; and its manufacturing method. SOLUTION: A Sin-coated graphite material comprises the graphite substrate, the surface of which is coated with SiC film by CVD method. In this case, the graphite substrate characteristically has an average pore size of 0.4-3 μm and a maximum pore size of 10-100 μm, the share of SiC in the surface layer of the graphite substrate at the depth of 150 μm from the surface of the graphite substrate is in a range of 15-50%, and an average crystal particle size of the SiC-membrane is in a range of 1-3 μm. Such a crystal is preferable as its intensity in diffractive peak by X-ray diffraction of the surface of SiC (III) of the surface of the SiC-membrane is 80% or more to the intensity of all the crystal surfaces (hkl). The manufacturing method comprises setting up the graphite substrate having an average pore size of 0.4-3 μm and a maximum pore size of 10-100 μm μm in a CVD reaction vessel and coating the substrate with SiC-membrane by CVD method at 1180-1300 deg.C at a concentration of 3-15 vol.% of a material gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a SiC-coated graphite member which can be suitably used as various members requiring heat resistance, including a member for heat treatment in semiconductor manufacturing, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Heat-treating members used in the manufacture of semiconductors, such as susceptors, liner tubes, process tubes, wafer boats, and equipment for pulling single crystals, have high purity and do not contaminate silicon wafers. In addition, it is required to have excellent thermal shock resistance against rapid heating and rapid cooling, and to be chemically stable and have high corrosion resistance.

[0003] For these heat-treating members, a graphite material having a SiC coating applied to a graphite substrate surface by a CVD method (chemical vapor deposition method) has conventionally been used. The formation of the SiC film by the CVD method uses, for example, hydrogen gas as a carrier gas and CH ₃ SiC containing Si atoms and C atoms in one molecule.
A method in which an organosilicon compound such as l ₃ , (CH ₃ ) ₃ SiCl, CH ₃ SiHCl ₂ is reduced and thermally decomposed in a gas phase, or a method in which a silicon compound such as SiCl ₄ is reacted with a carbon compound such as CH ₄ in a gas phase. , And a method of depositing SiC in a gas phase.

[0004] However, the SiC film formed by the CVD method has a thermal expansion property between the graphite substrate and the SiC film when a thermal shock is applied at the interface between the graphite substrate surface and the SiC film, for example, by rapid heating or quenching. Cracks occur in the SiC coating due to differences in physical properties such as modulus and elastic modulus,
There are drawbacks such as peeling of the iC coating.

Therefore, an attempt has been made to eliminate these problems by forming an intermediate layer at the interface between the graphite substrate surface and the SiC film. SiO gas is supplied to the surface of the graphite substrate under a high-temperature inert atmosphere to form SiC as an intermediate layer on the graphite surface by a contact reaction between the carbon gas and the SiO gas, and then the SiC film is applied by a CVD method or the like. A jig for heating a silicon wafer characterized by being deposited on an intermediate layer SiC is disclosed. This is because the bonding of the boundary surface is strengthened by the intermediate layer of SiC formed by the conversion method (CVR method) and the peeling of the SiC film is suppressed. It is difficult to form a uniform layer due to concentrated penetration into the pores, and a CVR process for forming the SiC intermediate layer is required, which complicates the manufacturing process and is disadvantageous in cost.

Japanese Patent Application Laid-Open No. Hei 3-257089 discloses a silicon carbide-coated graphite product comprising a graphite substrate on which a silicon carbide film is formed by a vapor phase growth method, wherein the surface of the graphite substrate is coated with silicon carbide. Si-S in which the SiC-C layer of the surface layer portion in which silicon is scattered and the microcrystals of silicon and silicon carbide are mixed.
a silicon carbide coated graphite product characterized in that only three layers of an iC layer and a silicon carbide film are laminated in this order, and a silicon film previously formed on a graphite substrate by a vapor phase growth method However, a method has been proposed in which a silicon carbide film is heat-treated at an atmosphere pressure of 30 Torr or less at a temperature equal to or higher than the melting point of silicon, and then a silicon carbide film is formed thereon by a vapor deposition method.
In this method, a Si film is formed on a graphite substrate surface and then heat-treated to form Si-S
An iC layer is formed to function as a stress relaxation layer between the SiC film and the graphite substrate. However, Si is melted in a temperature range higher than the melting point of Si due to the presence of Si, and Si-S
The strength of the iC layer is reduced, and the SiC layer is easily peeled off.
Further, even at a temperature lower than the melting point, there is a problem that the strength is reduced due to the diffusion of Si to the graphite side, and furthermore, the reaction between Si and C causes cracks or deformation.

Further, Japanese Patent Application Laid-Open No. Hei 6-305861 discloses that in a graphite member coated with silicon carbide by a chemical vapor deposition method, the surface roughness of the base material before coating with silicon carbide at least in a portion where cracks are likely to occur during use. Rmax is 100μ
m or more have been proposed. This is to reduce the residual stress on the silicon carbide coating surface that causes cracks by increasing the surface roughness of the base material surface, but the surface roughness of the silicon carbide coating surface also increases. For example, when the susceptor is used as a susceptor, there are problems in that the susceptor and the wafer are in point contact with each other at the wafer holding portion, so that the susceptor easily slips and causes particles.

[0008]

Accordingly, the present applicant has made intensive studies to solve these problems, and aims to improve the thermal shock resistance by forming a SiC film firmly on the graphite substrate surface. For this purpose, it has been found that the porosity of the graphite base and the particle properties of the SiC coating applied thereto have a large effect, and a graphite member having a SiC coating applied to the surface of the graphite base by a CVD method. The graphite substrate has pore properties of an average pore diameter of 0.4 to 3 μm and a maximum pore diameter of 10 μm or more, and the average particle diameter of the SiC coating applied to the graphite substrate is 3 μm.
A silicon carbide-coated graphite member characterized by having a particle size of 1 μm or less and a minimum particle size of 1 μm or less has been developed and proposed (Japanese Patent Application No. 11-114412).

[0009] The inventors of the present invention have disclosed a technique disclosed in Japanese Patent Application No. 11-1144.
As a result of further research based on the technology of No. 12, the ratio of the amount of SiC impregnated and deposited on the surface of the graphite substrate, that is, the ratio of the amount of SiC present in the surface of the graphite substrate, is determined by the coating strength and heat resistance of the SiC coating. It has been found that it has a significant effect on impact properties. The present invention has been developed on the basis of this finding, and its purpose is that a SiC film formed by a CVD method is firmly adhered to a graphite substrate surface, and is resistant to thermal shock such as rapid heating and rapid cooling. An object of the present invention is to provide a SiC-coated graphite member having excellent thermal shock resistance and excellent corrosion resistance, which is suitably used as, for example, a member for heat treatment in semiconductor manufacturing, and a method for manufacturing the same.

[0010]

A SiC-coated graphite member according to the present invention for achieving the above object is a graphite member having a surface of a graphite substrate coated with a SiC film deposited by a CVD method, comprising: Has an average pore diameter of 0.4 to 3 μm and a maximum pore diameter of 10 to 100 μm, and the occupation ratio of SiC in the graphite substrate surface layer portion having a depth of 150 μm from the graphite substrate surface is 15 to 50%, The constitution is characterized in that the average crystal grain size of the SiC film is 1 to 3 μm.

Further, in the SiC coating covering the graphite substrate surface, the intensity of the diffraction peak of the SiC (111) surface by X-ray diffraction of the SiC coating surface is 80% or more of the intensity of the whole crystal surface (hkl). It is characterized by the following.

[0012] In the production method, the average pore diameter is 0.1.
A graphite substrate having pore properties of 4 to 3 μm and a maximum pore diameter of 10 to 100 μm is set in a CVD reactor, the gas phase reaction temperature is 1180 to 1300 ° C., and the raw material gas concentration is 3 to
The method is characterized in that the graphite substrate surface is coated with a SiC film by a CVD reaction at a control of 15 Vol%.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The graphite substrate used in the present invention is not particularly limited. For example, it is required that the graphite substrate be as high as possible in order to be used as a heat treatment member in the production of semiconductors. In addition, an isotropic graphite material (CIP material) having low thermal anisotropy is preferably used.

In the SiC-coated graphite member of the present invention, the graphite substrate has an average pore diameter of 0.4 to 3 μm and a maximum pore diameter of 10 to 1 μm.
It is necessary to have a pore property specified as 00 μm. The porosity of the graphite base material is determined by filling the SiC particles deposited by the CVD method to form a SiC coating.
It exerts an important function for firmly attaching the C coating to the graphite substrate surface. That is, when the pore diameter is small, the precipitated SiC particles cannot penetrate deep into the pores and be filled, and it is difficult to firmly adhere the SiC coating. Therefore, in the present invention, the average pore diameter of the graphite substrate is set to 0.4 μm or more.

On the other hand, when the average pore diameter of the graphite base material is large, it is advantageous to infiltrate and fill the SiC particles precipitated by the CVD method, but the base material strength is reduced.
Further, when it is used for semiconductors, it is not preferable in terms of degassing for preventing contamination and generation of particles.
Therefore, the average pore diameter of the graphite substrate is set to 3 μm or less. In addition, the value measured by the mercury intrusion method is used for the pore properties.

The larger the pore size of the graphite substrate, the higher the Si
The graphite substrate used in the present invention has a maximum pore diameter of 10 μm or more because it is advantageous for filling the C particles and can firmly adhere the SiC coating. However, when the pore diameter of the graphite base material is increased, S
The iC particles are formed in the form of a film along the inner wall of the pores rather than being filled in the pores, and it is difficult to firmly adhere the iC particles. For this purpose, the maximum pore size is preferably 100 μm or less.

The SiC-coated graphite member of the present invention can be obtained by depositing S on a graphite substrate having these porous properties by a CVD method.
An iC coating is applied on the surface of the graphite substrate
It is characterized in that the iC occupancy is set in a specific range. S
Since the iC coating is formed by filling the pores on the graphite substrate surface with SiC particles vapor-deposited by the CVD method, the ratio of the SiC deposited and filled in the pores is the coating strength of the SiC coating. And thermal shock resistance.

Therefore, the SiC-coated graphite member of the present invention is:
The amount of SiC which is deposited and filled in the pores of the base material surface layer and is present in the base material surface layer portion is specified.The graphite base material surface portion refers to a base material portion having a depth of 150 μm from the graphite base material surface. The occupation ratio of SiC in the graphite base material layer within the range is 1
It is characterized in that it is set in the range of 5 to 50%.

The amount of SiC filled in the pores is deeper and deeper in the pores, and it is advantageous to precipitate and fill the pores in order to increase the SiC coating strength.
If it is less than 5%, the coating strength and thermal shock resistance of the SiC coating are low and not sufficient. On the other hand, it is necessary to increase the porosity itself of the graphite base material in order to obtain an occupation ratio exceeding 50%.
This will lead to a decrease in the strength of the substrate. Further, it is usually difficult to increase the occupation ratio to more than 50% by the CVD method. In addition, Si deposited and filled in the pores of the substrate
C enhances the adhesion strength of the SiC coating due to the so-called anchor effect. In the present invention, C specifies the amount of SiC in the substrate from the surface of the graphite substrate to a depth of 150 μm. The occupancy of SiC was determined by cutting the SiC-coated graphite material, observing the cut surface with a backscattered electron image of a SEM, and measuring the SiC occupancy.
Is the value obtained by measuring the area occupied by the area and by calculating the area ratio.

In the SiC-coated graphite member of the present invention, the SiC coating formed by vapor deposition on the surface of the graphite substrate having the above-mentioned porosity by CVD method and having an average crystal grain size of 1 to 3 μm is used. It is also characterized by having. In order for SiC particles precipitated by a gas phase reaction to enter pores of a graphite base material to efficiently fill pores and form a SiC coating,
The particle property of SiC deposited in the gas phase also affects the pore property of the graphite base material. Therefore, the SiC-coated graphite member of the present invention has an average pore diameter of 0.4 to 3 μm and a maximum pore diameter of 1 μm.
By setting the average crystal grain size of SiC particles forming a SiC film on a graphite substrate having a pore property of 0 to 100 μm to 1 to 3 μm, SiC is effectively deposited in pores on the surface of the graphite substrate, It is filled.

Further, the crystallinity of the SiC film is SiC (111).
The orientation to the plane is strong, and the intensity of the diffraction peak of the SiC (111) plane by X-ray diffraction is 80 times that of the entire crystal plane SiC (hkl).
% Or more of SiC (111)
Excellent corrosion resistance is imparted by the SiC film having a highly oriented surface.

In this SiC-coated graphite member, a graphite substrate having a porous property having an average pore diameter of 0.4 to 3 μm and a maximum pore diameter of 10 to 100 μm is set in a CVD reactor,
It is manufactured by coating a graphite substrate surface with a SiC film while controlling the gas phase reaction temperature at 1180 to 1300 ° C and the raw material gas concentration at 3 to 15 Vol%.

That is, in the method for producing a SiC-coated graphite member of the present invention, the graphite substrate having the above-mentioned porosity is formed by CVD.
The reactor was set in the reactor, and the CVD reaction conditions were a gas phase reaction temperature of 1180 to 1300 ° C. and a source gas concentration of 3 to 15
It is characterized in that SiC is vapor-phase deposited by a CVD reaction while controlling to Vol%.

In the CVD reaction, for example, a graphite substrate is
After the air in the system was evacuated by setting it in the reactor, it was heated to a predetermined temperature, and then hydrogen gas was fed in to replace the atmosphere with normal pressure hydrogen gas, and trichloromethylsilane and trichloromethylsilane were used as hydrogen gas as carrier gas. An organic silicon compound such as chlorophenylsilane, dichloromethylsilane, dichlorodimethylsilane, or chlorotrimethylsilane is supplied as a raw material gas to cause a gas-phase reduction reaction, whereby SiC particles are vapor-phase deposited on a graphite base material surface to form a SiC particle. A coating is formed and applied.

In this CVD reaction, when the reaction temperature for vapor-phase deposition of SiC is high, the kinetic energy of the raw material gas molecules is high, and the gas can penetrate deeply into the pores from the graphite substrate surface. As a result, the deposition rate of SiC is increased, so that SiC is easily deposited at a shallow portion in the pores. Therefore, the pores are closed by the SiC precipitated from the pore entrance portion to the intermediate portion of the graphite base material, and filling of the deep pores with SiC is inhibited.

On the other hand, when the reaction temperature is lowered, the kinetic energy of the raw material gas molecules is reduced, making it difficult to penetrate deep into the pores, and the deposition rate of SiC by the gas phase reduction reaction is also reduced. It is difficult to efficiently fill the pores with SiC. Therefore, the reaction temperature at which SiC is vapor-phase deposited by the CVD reaction is set in a temperature range of 1180 to 1300 ° C.

Further, when the concentration of the raw material gas is increased, the deposition rate of SiC is increased, so that the amount of SiC deposited on the pore surface increases, and it becomes impossible to fill the pores with SiC efficiently. Conversely, when the raw material gas concentration becomes low, it becomes difficult for the raw material gas to reach the deep part inside the pores, so that the inside of the pores cannot be efficiently filled. Further, the gas-phase reduction reaction is slowed down, resulting in inefficiency. Therefore, the source gas concentration is set in the range of 3 to 15% by volume.

As described above, by setting and controlling the CVD reaction conditions, the occupation ratio of SiC in the surface layer portion of the graphite substrate having a depth of 150 μm from the graphite substrate surface is increased to 15 to 50%, and S
The average crystal grain size of the iC film is set to 1 to 3 μm, and the X-ray diffraction peak intensity of the SiC (111) surface of the SiC film surface is changed to the whole crystal surface.
Sc coated with SiC coating of 80% or more of the strength of (hkl)
An iC-coated graphite member can be manufactured.

[0029]

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

Examples 1 to 7 and Comparative Examples 1 to 7 High-purity isotropic graphite materials having different porosity were prepared using
m, and processed to a thickness of 5 mm to obtain a graphite base material. These graphite substrates were set in a reaction tube of a CVD apparatus, and air was exhausted from the system, and then heated to a predetermined temperature, and normal pressure (0.1 MPa)
Hydrogen gas was fed in below, and the atmosphere was replaced with a hydrogen gas atmosphere. Then, using methyltrichlorosilane as a source gas and hydrogen gas as a carrier gas, methyltrichlorosilane /
The graphite substrate surface was coated with a SiC film by changing the concentration of methyltrichlorosilane in the mixed gas of hydrogen gas and the reaction temperature. Table 1 compares the production conditions of the SiC-coated graphite member.

With respect to the SiC-coated graphite member manufactured as described above, the SiC on the surface layer of the graphite base material was obtained by the following method.
The occupancy and the physical properties of the SiC coating were measured. In addition, a thermal shock test and a corrosion test were performed by the following method,
The thermal shock resistance and corrosion resistance were evaluated. Table 2 shows the obtained results. SiC occupancy of surface layer of graphite substrate, film thickness of SiC coating A SiC-coated graphite member is cut, and its cross section is observed with a backscattered electron image by SEM.
The area occupied by SiC in the surface layer portion of the base material portion up to m was measured, and the SiC occupancy was determined from the ratio. Further, the thickness of the SiC film was measured from SEM observation of the cross section. Average crystal grain size of SiC coating The surface of the SiC coating was observed by SEM to measure the average crystal grain size. Diffraction peak intensity ratio of SiC (111) plane From X-ray diffraction of the SiC coating surface, diffraction peaks of SiC (111) plane and all crystal planes (hkl) were obtained, and the diffraction peak intensity ratio of SiC (111) plane was calculated. . Thermal shock test By heating the lamp, the SiC-coated graphite
A heat cycle test of heating from 0 ° C. to 1200 ° C. and then cooling was repeated, and the number of tests when cracks or peeling occurred in the SiC film was obtained. However, in the embodiment, 50
The situation of the SiC coating after performing the thermal cycle test repeatedly was shown. In addition, during heating, rapid heating is performed from 200 ° C. to 1200 ° C. in 30 seconds, and when cooling, 1200 ° C. to 200 ° C.
For 1 minute. Corrosion test The sample was kept at 1200 ° C. for 15 hours in an atmosphere of 100% hydrogen chloride gas, and the weight loss rate was measured.

[0032]

[Table 1]

[0033]

[Table 2] Table notes; * 1 Whether or not cracks or peeling occurred in the SiC film after repeating the thermal cycle test 50 times. * 2 The number of thermal cycle tests when cracks or peeling occur in the SiC coating.

In Examples 1 to 7, films having excellent thermal shock resistance and corrosion resistance were obtained. Further, SiC impregnated in the graphite substrate formed a film. Comparative Example 1 has a low reaction temperature,
C occupancy is low, thermal shock resistance and corrosion resistance are inferior, and Comparative Examples 2, 3, and 4 have high reaction temperatures, so the SiC film has a large particle size and low SiC occupancy, and Comparative Example 5 has a low raw material concentration. In addition, the SiC film had a large particle size, was inferior in thermal shock resistance and corrosion resistance, and each of the SiC impregnated in the graphite substrate had a granular shape. In Comparative Example 6, since the raw material concentration was high, the SiC occupancy was low, and the thermal shock resistance and corrosion resistance were poor. In Comparative Example 7, it was found that the graphite base material had a large pore diameter, so the SiC occupancy was high, but the base material strength was low and the thermal shock resistance was poor.

[0035]

As described above, according to the SiC-coated graphite member of the present invention, the SiC occupancy indicating the amount of SiC impregnated and filled into the surface layer portion of the base material having a depth of 150 μm from the surface of the graphite base material whose porosity has been specified. By setting the ratio within the range of 15 to 50%, the coating strength of the SiC coating is increased by the anchor effect, and the orientation of the (111) crystal plane of the SiC coating is further increased to improve the thermal shock resistance and An SiC-coated graphite member having excellent corrosion resistance can be provided.
Further, according to the manufacturing method, the SiC-coated graphite member of the present invention can be manufactured by setting and controlling the gas phase reaction temperature and the raw material gas concentration in the CVD reaction. Therefore, for example, susceptors, liner tubes, process tubes, wafer boats, including various heat treatment members in semiconductor manufacturing such as single crystal pulling equipment members, various heat-resistant members that require heat resistance, and extremely useful as a manufacturing method. is there.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiharu Uei 1-3-2 Kitaaoyama, Minato-ku, Tokyo Inside Tokai Carbon Co., Ltd. (72) Inventor Yasuhiro Takizawa 1-2-3 Kitaaoyama, Minato-ku, Tokyo Tokai F term in Carbon Co., Ltd. (reference) 4G032 AA04 BA01 4K030 AA03 AA09 AA17 BA37 BB04 CA01 FA10 JA06 JA10 LA11

Claims (3)

[Claims] 1. S deposited on a graphite substrate surface by a CVD method.
A graphite member coated with an iC coating, wherein the graphite substrate has a pore property of an average pore diameter of 0.4 to 3 μm and a maximum pore diameter of 10 to 100 μm, and has a depth of 150 μm from the graphite substrate surface. Wherein the occupation ratio of SiC is 15 to 50%, and the average crystal grain size of the SiC coating is 1 to 3 μm. 2. The SiC (1) obtained by X-ray diffraction of the SiC coating surface.
11. The SiC-coated graphite member according to claim 1, wherein the intensity of the plane diffraction peak is 80% or more of the intensity of all crystal planes (hkl). 3. A graphite base material having an average pore diameter of 0.4 to 3 μm and a maximum pore diameter of 10 to 100 μm and having a pore property of C
It was set in a VD reactor, and the gas phase reaction temperature was set to 1180
A method for producing a SiC-coated graphite member in which a graphite substrate is coated with a SiC coating by a CVD reaction at a temperature of 1300 ° C. and a raw material gas concentration of 3 to 15 Vol%.