JPH0223510B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) This invention is applicable to epitaxial vapor phase growth of silicon wafers, etc., vapor phase growth of various other insulating films,
The present invention relates to a method for manufacturing a glassy carbon-coated carbon material used as a susceptor in processes such as vapor phase growth of polycrystalline films. (Prior art) Susceptors used in semiconductor manufacturing processes have generally been widely used, with the surface of a carbon material coated with silicon carbide. Due to the difference in susceptor, interlayer cracks and delamination are likely to occur during use of the susceptor, which may cause contamination of the silicon wafer due to impurities in the carbonaceous material. It is also difficult to respond to larger sizes. On the other hand, the halogenated linear polymer or natural organic polymer is decomposed in an inert atmosphere into a pitch-like compound in which the atomic composition ratio of carbon atoms and hydrogen atoms (hereinafter referred to as C/H ratio) of the product is 1. heating and mixing the resulting compound with an aromatic solvent to form a slurry, coating an article formed from carbon or ceramic material with the slurry, and subjecting the article to an inert atmosphere until the coating converts to glassy carbon. A method for manufacturing glassy carbon-coated articles by firing at moderately elevated temperatures is known (Japanese Patent Publication No. 39684/1984). Although this method certainly improved the occurrence of interlayer cracks and peeling, it had the disadvantage that pinholes were formed in the glassy carbon coating. When a pinhole occurs, impurities contained in the carbon material of the base material pass through the pinhole and come out onto the surface of the article, contaminating the silicon wafer or the like placed on the surface. (Problems to be Solved by the Invention) A glass-like carbon-coated carbon material that does not cause pinholes, cracks, or peeling, has a dense and smooth surface, and is useful as a susceptor in the semiconductor manufacturing process. It is an object of the invention to provide an advantageous manufacturing method. (Means for Solving the Problems) In order to solve the above-mentioned drawbacks, the inventors conducted intensive research on the degree of thermal decomposition of organic polymers. As a result, the inventors found that the above drawbacks can be overcome by using incomplete thermal decomposition products having an atomic composition ratio C/H of carbon to hydrogen of 1.1 or more and 20 or less, and have completed the present invention. That is, this invention dissolves an incomplete thermal decomposition product of an organic polymer in an organic solvent, applies it to the surface of a carbon material, dries it, and heats it in an inert environment to form glassy carbon on the surface of the carbon material. A method for producing a glassy carbon-coated carbon material, characterized in that the incomplete thermal decomposition product used for coating is one whose atomic composition ratio C/H of carbon and hydrogen is 1.1 or more and 20 or less. . This invention will be explained in detail below. The organic polymer used in this invention is preferably vinyl chloride resin, polyvinyl alcohol, oil-soluble phenolic resin, alkylphenol resin, chlorinated paraffin, chlorinated polypropylene, vinyl acetate resin, or polycarbonate resin. In particular, when the glassy carbon-coated carbon material is used as a susceptor for semiconductor manufacturing, vinyl chloride resin is particularly preferred from the viewpoint of impurities. For incomplete pyrolysis of these organic polymers, any type of granular or powdered material is
This is done by heating at ~700℃ for 30 minutes or more. The specific temperature and time of heating will vary depending on the heating device and type of organic polymer, but incomplete thermal decomposition products (hereinafter referred to as
As a result, the atomic composition ratio of carbon and hydrogen (hereinafter referred to as C/H ratio) of the PC material) is 1.1 or more and 20 or less,
It may be determined by experiment to preferably fall within the range of 1.1 or more and 2 or less, more preferably 1.1 or more and 1.5 or less. The C/H ratio can be measured by measuring the content of C and H using an ordinary elemental analyzer for organic compounds and calculating the ratio. Note that the inert environment herein means an inert atmosphere such as nitrogen or argon, or reduced pressure air. When the C/H ratio of the pyrolysis product is less than 1.1,
Although it is easily soluble in organic solvents, since it contains many hydrogen atoms, hydrogen gas is generated during carbonization, which causes bubbles to form in the glassy carbon coating, causing cracks and pinholes. When the C/H ratio of the thermal decomposition product exceeds 20, the thermal decomposition product becomes insoluble in the organic solvent and cannot be coated on the surface of the carbon material. An organic solvent is added to and dissolved in the pitch-like substance thus obtained to prepare a solution having a concentration of 10 to 300 g/g/, which is applied to the surface of the carbon material. The organic solvent is preferably an aliphatic chlorine solvent such as trichloroethylene or 1,1,1-trichloroethane, or an aromatic solvent such as benzene or toluene. Application methods include ultrasonic impregnation, brushing, spraying, and dipping. After application, it is preferable to dry at a relatively low temperature (50 to 100°C). After coating, the PC material is vitrified by heating at 800 to 1300°C for 30 minutes or more in an inert environment to obtain a glassy carbon-coated carbon material. Note that the inert environment is as described above. Next, the carbon material preferably has a bulk density of 1.6 to 2.0 g/
cm ³ of graphite. Carbon materials with lower bulk densities have too low strength, poor durability, and large open porosity, making it difficult for coating solvents to penetrate the surface and easily causing pinholes, whereas carbon materials with higher bulk densities Since carbonaceous materials have few pores on their surfaces and are too smooth, a coating film formed from a solution of a thermal decomposition product of an organic polymer easily peels off. (Example) Examples 1 to 4 Vinyl chloride resin (SS-110 manufactured by Denki Kagaku Kogyo Co., Ltd.)
100 g was placed in a tube furnace and heated for 90 minutes under an argon gas atmosphere at the temperature shown in the table. The C/H ratio of the produced PC material was measured using a CHN coder. Grind the PC material in a mortar and add benzene to dissolve it at the concentration shown in the table. This solution is made isotropic and a carbon material (30 mm x 50 mm x 10 mm) with a bulk density of 1.75 g/cm ³ is prepared.
It was applied by dipping method. Next, it was carbonized by heating at 1200° C. for 1 hour in an argon gas atmosphere. After repeating coating and heating several times, the film thickness became 15μm.
A glassy coated carbon material was produced. Five sheets of carbon material were prepared for each manufacturing condition, and solution application and carbonization were repeatedly performed on each sheet. The obtained product was evaluated by observing the number of pinholes using a microscope and measuring the amount of gas permeation (manufactured by LYSSY).
(using GPM-200 type equipment). The number of pinholes was observed for all five test pieces, and the amount of gas permeation was measured for only one of the five test pieces. The measured value of the amount of gas permeation indicates the degree of denseness of the coating, and the smaller the value, the denser it is considered to be. The results of evaluating the manufactured carbon materials are summarized in the table. Examples 5 to 8 Same as Examples 1 to 4 except that vinyl acetate resin (Denki Kagaku Kogyo Co., Ltd. SH-10) and alkylphenol resin (Nippon Kasei Kogyo Co., Ltd. 2306N) were used instead of vinyl chloride resin. A glassy coated carbon material was produced in the same manner. The manufacturing conditions and the results of evaluating the manufactured carbon materials are shown in the table. Comparative Examples 1 to 8 PC substances with a C/H ratio of less than 1.1, or 20
The procedures were carried out in accordance with Examples 1 to 8, except that a material exceeding 20% was used. The manufacturing conditions and the results of evaluating the manufactured carbon materials are shown in the table.

【table】

[Table] (Effects of the invention) The glass-like coated carbon material obtained by this invention has almost no pinholes, and the gas permeation rate using helium gas is 1×10 ^-10 cc/
Shows excellent gas impermeability of less than cm ² sec.

Claims (1)

[Claims] 1. When an incomplete thermal decomposition product of an organic polymer is dissolved in an organic solvent, applied to the surface of a carbon material, dried, and heated in an inert environment, the surface of the carbon material is coated with glassy carbon. , as the incomplete thermal decomposition product, the atomic composition ratio of carbon and hydrogen C/H
A method for producing a glassy carbon-coated carbon material, characterized in that a carbon material coated with glassy carbon is used.