JP2002003275A - SiC FORMED BODY WITH HINDERING LIGHT TRANSMISSION AND ITS MANUFACTURING METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a SiC formed body with a hindering light transmission and its manufacturing method having a high hindering light transmission and being preferably utilized for various components for a semiconductor manufacturing, for example a shielding body, a dummy wafer and the like, or a heat resistant component for a heat treatment apparatus. SOLUTION: The SiC formed body with the hindering light transmission is comprised of the SiC formed body that is manufactured by a chemical vapor deposition(CVD) method, a texture and a structure of a fine grain polycrystalline and a light transmittance of 0.3% or less at the wavelength range of 500 to 3000 nm. A grain size of a crystal preferably comprises of 1 to 5 μm. In the manufacturing method of the SiC formed body of which SiC is deposited on a surface of a substrate by the CVD method and the substrate is removed after a film formation, its manufacturing method is comprised of placing the substrate in a Muffle furnace which is provided in a CVD reaction chamber, controlling a resident time of a raw material gas at 2 to 10 seconds and setting a film formation speed at 80 to 400 μm/hr.

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 light-impermeable SiC molded article that can be suitably used as various members such as a dummy wafer, a susceptor, and a pin used in a diffusion furnace apparatus, an etching apparatus, a CVD apparatus, and the like of a semiconductor production apparatus, and a method for producing 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.

As a light-transmitting SiC molded body, for example, Japanese Unexamined Patent Publication 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 μm. About 20 at 3 microns
Freestanding β deposited by chemical vapor deposition with a damping constant of less than cm ^-1
-SiC has been proposed. SiC by this CVD method
It is known that the higher the purity of the molded body, the higher the light transmittance of the obtained SiC is, and the molded article has a theoretical density of 100% and high purity, that is, metal impurities of 5 ppm or less, preferably about 3.5 ppm or less. It is disclosed that it is a metal impurity.

However, such a high purity CV
Since the SiC molded body obtained by the method D has optical transparency, when the SiC molded body is used as various members of a semiconductor manufacturing apparatus, a heat treatment apparatus, or the like, depending on the field of application, the S
The physical properties of iC can be problematic.

For example, semiconductor manufacturing processes include rapid thermal annealing, rapid thermal cleaning, rapid thermal chemical vapor deposition, rapid thermal oxidation. ), Rapid thermal nitriding (rap
id thermal nitridation) (refer to RTP).
In Japanese Patent Application Laid-Open Publication No. H11-157, it is proposed that the shield is made of SiC so that the wafer substrate exhibits excellent in-plane uniformity even by high-speed heating, and a material property that is opaque to radiant heat is required.

In this RTP, accurate temperature control of the wafer substrate is required. However, when measuring the temperature with a pyrometer, when the black body cavity is formed on the surface opposite to the processing surface of the wafer substrate, the temperature of the wafer is reduced. 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 JP-A-6-341905, in order to prevent light leaking from the heating element from entering the reflection cavity, a partition wall and a guard ring for 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.

In addition, a dummy wafer used for stabilizing wafer processing conditions in plasma etching processing or CVD processing is required to have low light transmittance. The wafer is mounted on the support boat by the transfer robot, but the wafer is recognized by irradiating laser light, so if the light transmittance of the wafer is high, the detector can accurately recognize the position of the wafer. This makes it 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 when it has a high purity, it exhibits a yellow color and has light transmittance, and it is generally difficult to reduce the light transmittance. . For example, as a means for scattering light on the surface to reduce the light transmittance, there is a method of roughening the surface.
When irradiated with light of 00 nm, those having a surface roughness Ra of 10 nm or less and having a mirror-like property exhibit a transmittance of 40 to 60%,
When the surface roughness Ra is 300 to 500 nm, 0.3
０．８0.8% transmittance and the light transmittance is reduced.
It cannot be said that it has satisfactory light opacity in a wide wavelength range from 00 to 2500 nm.

[0011]

Therefore, the applicant of the present invention
A study was conducted on the relationship between the properties of the VD-SiC molded body and the optical characteristics, and as a SiC molded body with low light transmittance, CVD was performed.
A CVD-SiC molded body obtained by the method, comprising at least one SiC layer having a different particle property on the surface or inside thereof, and having a light transmittance of 0.4% or less in a wavelength region of 300 to 2500 nm, A SiC molded body having a light transmittance of not more than 2.5% in a wavelength range exceeding 2500 nm;
And a method for producing a CVD-SiC molded body, in which a SiC film is formed on a graphite substrate surface by CVD and then the substrate is removed.
Developed a method of manufacturing a SiC molded body in which at least one SiC layer having different particle properties is formed on the surface or inside of the CVD-SiC molded body by changing the setting of the CVD reaction conditions (Japanese Patent Laid-Open No. 11-228233). did.

Further, the applicant of the present invention is a CVD-SiC molded body composed of β-type crystal obtained by a CVD method, wherein a visible light-impermeable CVD-SiC layer having a thickness of 2 to 20 μm is formed on the surface or inside thereof. At least one layer is formed,
The light transmittance in the wavelength range of 300 to 2500 nm is 0.4
% Or less, and a CVD-forming method in which a SiC film is formed on a substrate surface by a CVD reaction and then the substrate is removed.
In the method for producing a SiC molded body, at least one layer of a visible light opaque CVD-SiC layer is formed on the surface or inside of the CVD-SiC molded body by changing the CVD reaction conditions in the process of forming the SiC coating. (Japanese Patent Application Laid-Open No. 12-119064) has been developed and proposed.

[0013] The above-mentioned technique is based on the existence of a layer for scattering and reflecting light as a material structure of the SiC molded body.
The present invention is based on the result of finding that light transmittance can be lowered, and the present invention has been developed as a result of further research based on these findings. That is, an object of the present invention is to provide high purity, high heat resistance and high strength properties, and particularly excellent light impermeability, for example, various members for manufacturing a semiconductor such as a shield or a dummy wafer, or various heat resistant members for a heat treatment apparatus. It is an object of the present invention to provide a CVD-SiC molded body composed of a β-type crystal with high purity which can be suitably used as a method, and a method for producing the same.

[0014]

The light-impermeable SiC molded body according to the present invention for achieving the above object is a SiC molded body produced by a CVD method, and has a fine grain polycrystalline structure. In this case, the light transmittance in the wavelength range of 500 to 3000 nm is not more than 0.3%. The crystal grain size in the fine-grained polycrystalline structure is preferably 1 to 5 μm.

Further, the method for producing a light-impermeable SiC molded article according to the present invention is directed to a method for producing a SiC molded article in which SiC is deposited on a substrate surface by a CVD method, a film is formed, and then the substrate is removed. A structural feature is that the substrate is placed in a muffle provided in the reaction chamber, the residence time of the source gas is controlled to 2 to 10 seconds, and the film forming rate is set to 80 to 400 μm / hr. I do.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A SiC molded body by a CVD method is:
It is manufactured by depositing SiC on the substrate surface by a CVD method to form a SiC coating, and then removing the substrate. In the process of forming a SiC film, first, a raw material gas undergoes a gas phase reaction to generate a nucleus of SiC on a substrate surface.
The iC nucleus grows into amorphous SiC, and further grows into a columnar crystal structure via finer polycrystalline SiC grains to form a SiC film. Therefore, SiC
The physical properties such as the strength properties, thermal properties, optical properties, etc. of the film, ie, the CVD-SiC molded body, differ depending on the crystal properties of the SiC film formed by deposition on the substrate surface.

In the case where the SiC film has fine polycrystalline grains, since the crystal orientation is random, the crystal boundaries exhibit a textured structure assembled with various orientations. When light passes through such a tissue structure, complex light scattering, refraction, reflection, etc. occur at the crystal boundary surface, causing a phenomenon that light is confined, resulting in a decrease in light transmittance, that is, light impermeability. Will be increased.

The light-impermeable SiC compact of the present invention has a fine-grained polycrystalline SiC crystal structure structure. Light scattering, refraction, reflection, and the like occur, confining the light and lowering the light transmittance. And 500-30
The light transmittance in the wavelength range from visible light to near infrared light of 00 nm can be reduced to 0.3% or less. in this case,
Preferably, the crystal grain size constituting the fine-grained polycrystal is 1 to 5 μm.
It is.

The light-impermeable SiC molded body is formed by depositing SiC on a substrate surface by a CVD method, forming a film, and then removing the substrate. The substrate is placed in the container, the residence time of the source gas is controlled to 2 to 10 seconds, and the film forming rate is set to 80 to 4
It is manufactured by setting to 00 μm / hr.

A CVD-SiC molded body is prepared by setting a base material in a reaction chamber of a CVD reaction furnace, and depositing S
It is manufactured by a method of depositing a SiC film by vapor-phase deposition of iC, forming a SiC film, and then removing the base material. Carbon-based materials, metal-based materials such as silicon, quartz, etc. are used as the base material. Carbon-based materials, which have good workability and can be easily burned off by heat treatment in air, especially high-purity graphite materials Is preferably used. After forming the SiC film, the method of removing the substrate is performed by cutting, polishing, burning away in air, or a combination thereof as appropriate to obtain a CVD-SiC film having a thickness of 0.3 to 5 mm. A molded article is obtained.

In the CVD reaction, a substrate is set in a reaction chamber, the air in the system is evacuated, heated and maintained at a predetermined temperature, and then a hydrogen gas is fed in to replace the atmosphere with a normal pressure hydrogen gas atmosphere. A method in which a halogenated organosilicon compound such as trichloromethylsilane, trichlorophenylsilane, dichloromethylsilane, or dichlorodimethylsilane is supplied as a source gas using hydrogen gas as a carrier gas and subjected to gas phase reduction thermal decomposition, or a method such as silicon tetrachloride. A SiC film is formed by depositing SiC on the substrate surface by a method in which a mixed gas of a silicon compound and a carbon compound such as methane is fed as a raw material gas and reacted in a gas phase. CVD reaction is 1
It is preferable to carry out at a temperature of 150 to 1500 ° C. 11
At a temperature lower than 50 ° C., the film forming rate is low, and the efficiency becomes inefficient.
In addition, there is a risk that metal silicon is mixed in the SiC coating. On the other hand, when the reaction temperature exceeds 1500 ° C., the uniformity of the film thickness and film quality decreases.

According to the manufacturing method of the present invention, when this SiC film is formed, a muffle 1 is provided in a CVD reaction chamber as schematically shown in FIG. Place. The muffle 1 is provided with several to a dozen or more nozzles 3 for feeding the raw material gas. The nozzle 3 is preferably installed so that the raw material gas does not directly hit the substrate 2, for example, such that the nozzle tip faces the wall surface of the muffle 1, and the raw material gas is preferably indirectly contacted with the substrate 2.
This is because if the raw material gas sent from the nozzle 3 directly hits the base material, unevenness in film thickness and unevenness in the SiC film is likely to occur. Further, in the case where the nozzle is blocked by SiC deposited during the CVD reaction, it is possible to continuously perform the CVD reaction without interruption by appropriately switching and using the nozzle 3.

The reason for providing this muffle is that the reaction volume is reduced, and the adjustment of the source gas concentration is substantially facilitated, thereby promoting the generation of SiC nuclei in the CVD reaction and forming the microcrystalline polycrystalline structure. It is intended. In this case, as the CVD reaction conditions, the residence time of the source gas is set to 2 to
By controlling to 10 seconds, the film forming speed of the SiC film is set to 80 to 40.
It is necessary to set it to 0 μm / hr.

The residence time of the raw material gas is a parameter indicating the time during which the raw material gas stays in the CVD reaction chamber (muffle) during the CVD reaction and participates in the reaction, and is calculated by the following equation. Value.

By controlling the residence time of the raw material gas to 2 to 10 seconds, the film forming speed can be set to 80 to 400 μm / hr. When the film formation rate is low, it is difficult to form a fine-grained polycrystalline structure, and the rate of growth into a crystal structure increases. on the other hand,
When the deposition rate is high, the heterogeneity of the structure increases.

[0026]

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

Example 1 A muffle having a volume of about 35 l was set in a CVD reaction chamber, and a high-purity isotropic graphite plate (base material) having a diameter of 205 mm and a thickness of 5 mm was placed in the muffle. In addition, six source gas introduction nozzles were inserted into the muffle in a direction that did not directly hit the graphite substrate. After replacing the inside of the system with hydrogen gas, a raw material gas containing 7.5 vol% of trichloromethylsilane / hydrogen was introduced at a flow rate of 92 l / min in order to control the residence time of the raw material gas to 4 seconds. A CVD reaction was performed at a CVD reaction temperature of 1400 ° C. and a reaction time of 4 hours, and a SiC film was formed on the graphite base material surface. Then, the SiC film on the outer peripheral portion was ground and removed to expose the graphite base material. Thus, the graphite substrate was removed by burning. Obtained S
The average thickness of the iC coating was 1050 μm, and the deposition rate was 263 μm / hr. Then, it was planarized by polishing to produce a SiC molded body having a diameter of 200 mm and a thickness of 500 μm.

Examples 2 to 7 and Comparative Examples 1 to 4 The SiC film was formed by changing the flow rate of the source gas in order to set and control the residence time and the deposition rate of the source gas, and by changing the CVD reaction temperature and the reaction time. Except that a film was formed, a CVD reaction, removal of a graphite substrate and polishing were performed in the same manner as in Example 1 to obtain a SiC having a diameter of 200 mm and a thickness of 500 μm.
A molded body was produced.

Comparative Example 5 Si having a diameter of 200 mm and a thickness of 500 μm was prepared by a reaction sintering method.
A C compact was produced.

Comparative Example 6 An SiC film having a thickness of about 100 μm was applied on the SiC molded body produced in Comparative Example 5 by a CVD method (at a temperature of 1400 ° C.) to form an SiC film having a diameter of 200 mm and a thickness of 600 μm. The body was made.

Next, the thickness of these SiC compacts was adjusted to 500 μm by surface grinding, and the crystal grain size and light transmittance were measured by the following methods. Was done. From the SEM observation photograph of the surface of the SiC compact,
The crystal grain size was measured. Light transmittance: 500 to 500 mm using a 5 mm-thick metal aluminum plate as a standard sample and a self-recording spectrophotometer manufactured by Shimadzu Corporation.
The light transmittance in the wavelength region of 3000 nm was measured and calculated by the following equation. T = BA, where T: light 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 Thermal shock resistance: sample in an inert atmosphere at 500 ~ 1
A heat cycle test of heating and cooling to 200 ° C. was performed 20 times, and the state of the sample was observed. When a crack was generated in the sample during the test, the number of heat cycle tests at the time of the crack generation was measured. Corrosion resistance: The rate of weight loss when the sample was kept for 15 hours in a stream of 100% hydrogen chloride at 1200 ° C. (5 l / min) was measured.

Table 1 shows the production conditions of the SiC compact thus produced, and Table 2 shows the results of the measurement test.

[0033]

[Table 1]

[0034]

[Table 2]

From the results shown in Tables 1 and 2, the Si
It can be seen that the C molded product has a low light transmittance of 0.3% or less in the wavelength region of 500 to 3000 nm, has a good surface appearance of the SiC molded product, and has excellent thermal shock resistance and corrosion resistance. On the other hand, in Comparative Example 1, the light transmittance was low, but the reaction temperature was low, the film formation rate was low, the formation of a fine-grained polycrystalline structure was not sufficient, and the surface was glossy.
Poor thermal shock resistance and corrosion resistance. In Comparative Example 2, the film formation rate was high, and in Comparative Example 3, the source gas residence time was short, so that the heterogeneity of the structure was large, the surface appearance was uneven, and the thermal shock resistance was low. It can be seen that the light transmittance is high in Comparative Example 4 in which the film formation rate is low while the source gas residence time is long. In Comparative Examples 5 and 6 using the SiC sintered body, the light transmittance was low, but the surface irregularities of the molded body were remarkable, and the thermal shock resistance and the corrosion resistance were remarkably poor.

[0036]

As described above, the light-impermeable Si of the present invention is used.
According to the C sintered body, since it has a fine-grained polycrystalline structure, the light transmittance is low, and the light transmittance in the wavelength region of 500 to 3000 nm is particularly excellent in light impermeability of 0.3% or less. Further, a dense and high-purity SiC molded body is provided. Further, according to the manufacturing method, a muffle is provided in the CVD reaction chamber, and the residence time and the film forming rate of the source gas are controlled and set to thereby provide excellent light impermeability having a fine-grained polycrystalline structure. A SiC molded body can be manufactured.
Therefore, for example, various heat-resistant members such as a heat treatment device shield and a soaking ring for a semiconductor manufacturing device, or various types of dummy wafers, susceptors and pins used for a diffusion furnace device, an etching device, and a CVD device for a semiconductor manufacturing device. Light-impermeable Si that can be suitably used as a member
It is extremely useful as a C compact and a method for producing the same.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a method of forming a SiC coating for producing a light-impermeable SiC molded body of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Muffle 2 Substrate 3 Raw material gas nozzle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenichi Kanai 1-3-2 Kitaaoyama, Minato-ku, Tokyo Tokai Carbon Co., Ltd. F-term (reference) 4G001 BA77 BB22 BC22 BC73 BD04 BD31 BD37 BD38 BE22 BE32 4G052 DA02 DB10 DC01 DC09 4K030 AA05 AA06 BA37 BB03 BB04 CA05 DA08 KA41 LA01 LA11

Claims (3)

[Claims] 1. A SiC molded body produced by a CVD method, having a fine-grained polycrystalline structure,
A light-opaque SiC molded body having a light transmittance of 0.3% or less in a wavelength region of 3000 nm. 2. The light-impermeable SiC compact according to claim 1, wherein the crystal grain size is 1 to 5 μm. 3. A method for producing a SiC molded body in which SiC is deposited on a substrate surface by a CVD method, and after forming a film, the substrate is removed, the substrate is placed in a muffle provided in a CVD reaction chamber. A method for producing a light-opaque SiC molded body, wherein the deposition time is set to 80 to 400 μm / hr while controlling the residence time of the raw material gas to 2 to 10 seconds.