Heat-resistant member and manufacturing method thereof

Abstract

To provide a heat-resistant member in which a surface of a base material made of isotropic graphite is coated with a carbide coating film, and which is less likely to contaminate a surface of the carbide coating film or damage the coating film, and to provide a method for manufacturing the same.SOLUTION: A heat-resistant member includes a base material made of isotropic graphite, and a carbide coating film formed on all or a part of a surface of the base material, which is made of a sintered body containing a metal carbide as a main component. A coverage of an impurity film adhered to a surface of the carbide coating film is less than 3%. An arithmetic mean roughness Ra of the carbide coating film is 1.5 μm or less. Such a heat-resistant member is obtained by applying a blasting treatment to a heat-resistant member precursor to which the impurity film is adhered to the surface of the carbide coating film, by impinging a soft medium on the surface of the carbide coating film. The medium is made of a non-metallic material with a new Mohs hardness of 4 or less and a true specific gravity of 2.5 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat-resistant member and a manufacturing method thereof, and more particularly to a heat-resistant member in which the surface of a substrate made of isotropic graphite is coated with a carbide coating, and the carbide coating surface is less contaminated and damaged, and a manufacturing method thereof. [Background technology]

[0002] Semiconductor processes such as bulk single crystal growth and epitaxial film formation of SiC and group III nitride semiconductors are subject to severe processing conditions. Components used in these processes, such as crucibles and susceptors (hereinafter collectively referred to as "heat-resistant components"), are exposed to high temperatures and highly corrosive atmospheres during the processes. Conventionally, SiC-coated graphite materials and pBN-coated graphite materials have been used for such heat-resistant components. However, these materials have a problem of short lifespan in the current semiconductor processing environment.

[0003] To solve this problem, various proposals have been made. For example, Patent Document 1 discloses a high-temperature heat-resistant member including a graphite substrate made of isotropic graphite and a TaC coating having a non-oriented granular structure that covers the surface of the graphite substrate. The same document states: (A) The TaC coating has a non-oriented granular structure, which makes it difficult for cracks to propagate. (B) As a result, the graphite substrate is protected even when the high-temperature resistant component is used for a long time in a high-temperature atmosphere; and (C) Such high-temperature resistant components can be used as susceptor components for MOCVD epitaxial growth of III-nitrides. is stated.

[0004] Patent Document 2 discloses a high-temperature heat-resistant member including a graphite substrate having chamfered corners and a TaC coating that covers the surface of the graphite substrate. The same document states: (A) If there are corners on the surface of the graphite substrate, the TaC coating is likely to crack, peel, or peel off locally during deposition or use; and (B) Chamfering the corners of the graphite substrate can prevent cracking, lifting, peeling, etc. of the TaC coating during deposition or use. is stated.

[0005] Patent Document 3 states: (a) A slurry containing TaC particles is applied to the surface of a graphite substrate to form a coating film; (b) drying the coating film to form a formed film; (c) polishing the surface of the formed film to reduce the surface roughness or surface waviness of the formed film; (d) The formed film is heated to sinter the TaC particles, thereby obtaining a sintered film. A method for manufacturing a heat-resistant graphite member is disclosed. The same document states: (A) When the sintered film is subjected to processing such as polishing or grinding, there is a risk of microcracks occurring in the sintered film, and (B) Polishing is easier when polishing a molded film instead of a sintered film. is stated.

[0006] In Patent Document 4, a TaC film is formed on the surface of a graphite substrate, and the coefficient of thermal expansion (CTE) of the graphite substrate is 5.8 to 6.4 × 10 -6 / K and a bulk density of 1.83 to 2.0 g / cm 3 A heat-resistant graphite member is disclosed. The document describes that when a TaC coating is formed on the surface of a graphite substrate, the durability and heat resistance are improved by optimizing the CTE and bulk density of the graphite substrate.

[0007] Patent Document 5 discloses a high heat-resistant member in which the surface of a substrate made of isotropic graphite is coated with a TaC film, and the TaC film has an iron content of 20 to 1000 mass ppm. The document describes that optimizing the amount of iron in TaC suppresses the occurrence of cracks in the TaC film and improves the heat resistance of the TaC coating.

[0008] Patent Document 6 states: (a) A ceramic coating is formed on the surface of a substrate using a physical vapor deposition method such as high-velocity gas jet spraying, chemical vapor deposition (CVD), or cold spraying. (b) The surface of the ceramic coating is subjected to surface treatment such as polishing, grinding, brushing, blasting, ball shot, wire shot, dry ice shot, etching, pickling, etc. A method for depositing a ceramic coating is disclosed. The document states that this method can suppress the generation of fine particles from the coating.

[0009] Furthermore, Non-Patent Document 1 discloses a method in which TaC slurry is applied to a graphite substrate and sintered. The same document states: (A) By using this method, a TaC coating having a thickness of 50 to 200 μm can be formed, and (B) The obtained TaC coating has a dense granular structure containing coarse particles of 10 to 50 μm, and is free of cracks or pinholes penetrating the coating. is stated.

[0010] A method of applying a slurry containing metal carbide to a substrate and sintering the coating (hereinafter simply referred to as the "sintering method") can form a dense carbide coating on the substrate surface. However, a pyrolytic carbon film resulting from the organic binder may remain as residue on the carbide coating formed by the sintering method. The pyrolytic carbon film can be a source of carbon impurities in the actual process in which the heat-resistant component is used.

[0011] Pyrolytic carbon films are chemically stable and therefore difficult to remove by chemical cleaning or other methods. On the other hand, they can be removed by mechanical removal methods (e.g., grinding, ceramic blasting, etc.). However, mechanical removal methods have the risk of contaminating the surface of the carbide coating with abrasives or blasting media, or of the abrasives or blasting media damaging the coating. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-075814 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-193943 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-044719 [Patent Document 4] Japanese Patent Application Laid-Open No. 2017-075075 [Patent Document 5] Japanese Patent Application Publication No. 2018-145022 [Patent Document 6] Japanese Patent Application Laid-Open No. 2017-014569 [Non-patent literature]

[0013] [Non-Patent Document 1] D. Nakamura et al., Appl. Phys. Lett. 106(8)(2015)082108 Summary of the Invention [Problem to be solved by the invention]

[0014] An object of the present invention is to provide a heat-resistant member, and a method for manufacturing the same, in which the surface of a substrate made of isotropic graphite is coated with a carbide coating, with little contamination of the carbide coating surface and little damage to the coating. [Means for solving the problem]

[0015] In order to solve the above problems, the heat-resistant member according to the present invention has the following configuration. (1) The heat-resistant member is a substrate made of isotropic graphite; a carbide coating formed on all or part of the surface of the substrate and made of a sintered body containing metal carbide as a main component; It is equipped with: (2) The coverage of the impurity film adhering to the surface of the carbide coating is less than 3%. (3) The carbide coating has an arithmetic mean roughness Ra of 1.5 μm or less.

[0016] The method for manufacturing a heat-resistant member according to the present invention has the following features. (1) The method for manufacturing the heat-resistant member includes the steps of: a first step of preparing a heat-resistant member precursor, the heat-resistant member precursor including a base material made of isotropic graphite, a carbide coating made of a sintered body containing metal carbide as a main component formed on all or part of the surface of the base material, and an impurity film attached to the surface of the carbide coating; a second step of subjecting the surface of the carbide coating to a blasting treatment in which soft media is collided with the surface to obtain the heat-resistant member according to the present invention; It is equipped with: (2) The media is made of a non-metallic material having a new Mohs hardness of 4 or less and a true specific gravity of 2.5 or less. [Effects of the Invention]

[0017] For heat-resistant components with a carbide coating formed on the substrate surface and an impurity film attached to the carbide coating surface, blasting (soft blasting) can be performed to remove the impurity film on the carbide coating easily and at low cost without damaging the carbide coating. Furthermore, soft media made of nonmetallic materials do not contaminate the carbide coating, or, if contaminated, can be easily removed. Therefore, when the heat-resistant components obtained in this manner are used, for example, as susceptors in semiconductor film deposition processes, unintended contamination of impurities can be prevented, and process reproducibility is expected to be improved. [Brief explanation of the drawings]

[0018] [Figure 1] Fig. 1(A) is an optical microscope photograph of the carbide coating surface after blasting (Example 1), and Fig. 1(B) is an optical microscope photograph of the carbide coating surface before blasting (Comparative Example 2). DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will be described in detail below. [1. Heat-resistant materials] The heat-resistant member according to the present invention comprises: a substrate made of isotropic graphite; a carbide coating formed on all or part of the surface of the substrate and made of a sintered body containing metal carbide as a main component; It is equipped with:

[0020] [1.1. Base material] [1.1.1. Isotropic graphite] The base material is made of isotropic graphite. "Isotropic graphite" refers to polycrystalline graphite material produced by cold isostatic pressing (CIP). Graphite is a hexagonal crystal system, so its properties are anisotropic. On the other hand, isotropic graphite has the advantage that the crystal orientation of each crystal grain is unoriented, so there is no difference in properties depending on the cutting direction. In the present invention, the shape, size, etc. of the substrate are not particularly limited, and an optimum shape can be selected depending on the purpose.

[0021] 1.1.2. Average coefficient of thermal expansion "Average coefficient of thermal expansion" refers to the average value of the coefficient of thermal expansion (CTE) in the temperature range from room temperature to 500°C. The average CTE of the substrate affects the durability of the carbide coating. If the average CTE of the substrate is too small, the difference in the thermal expansion coefficient between the substrate and the carbide coating becomes large, making the carbide coating more susceptible to peeling. Therefore, the average CTE of the substrate should be less than 3.8 × 10 -6 / K or more. The average CTE is preferably 4.0×10 -6 / K or more, more preferably 4.2 × 10 -6 / K or higher.

[0022] On the other hand, if the average CTE of the substrate becomes too large, the substrate becomes prone to warping after film formation. Therefore, the average CTE of the substrate is 7.0 × 10-6 / K or less. The average CTE is preferably 6.5×10 -6 / K or less, more preferably 6.0 × 10 -6 / K or less.

[0023] The average CTE of isotropic graphite is typically 3.8-7.0×10 depending on its manufacturing method and composition. -6 / K. Therefore, it is preferable to select one with an appropriate average CTE from various isotropic graphites as the substrate material. For example, when the metal carbide is TaC, the average CTE of the substrate is 5.5 to 7.0 × 10 -6 When the metal carbide is WC, the average CTE of the substrate is preferably 3.8 to 5.0 × 10 -6 / K is preferred.

[0024] [1.2. Carbide Coating] [1.2.1. Formation location] A carbide coating is formed on the surface of the substrate. The carbide coating may be formed on the entire surface of the substrate, or may be formed on only a part of the surface. The location where the carbide coating is formed can be selected optimally depending on the purpose.

[0025] [1.2.2. Number of layers] The carbide coating may be composed of a single layer having the same composition and microstructure, or may be a laminate of multiple layers having different compositions and / or microstructures. In the latter case, the number of layers included in the carbide coating is not particularly limited, and the optimal number of layers can be selected depending on the purpose.

[0026] [1.2.3. Porosity] The porosity of the carbide coating is not particularly limited, and an optimum value can be selected depending on the purpose. For example, when the carbide coating is composed of a single layer, if the porosity of the carbide coating is too large, corrosive gases will reach the substrate surface, facilitating corrosion of the substrate. Therefore, the porosity of the carbide coating is preferably less than 3%. To suppress corrosion of the substrate, the smaller the porosity of the carbide coating, the better. On the other hand, when the carbide coating is a laminate of multiple layers with different compositions and / or microstructures, it is sufficient that at least one layer is dense, and the remaining layers do not necessarily have to be dense.

[0027] [1.2.4. Composition] The carbide coating is made of a sintered body containing metal carbide as a main component. The phrase "mainly composed of metal carbide" means that the content of metal carbide in the carbide coating is 90 at % or more. The "content (at%) of metal carbide" refers to the ratio of the sum of the number of atoms of the metal element constituting the metal carbide and the number of carbon atoms (for example, if the metal carbide is TaC, the sum of the number of Ta atoms and the number of C atoms) to the total number of atoms contained in the carbide coating.

[0028] The composition of the carbide coating is not particularly limited, and an optimum composition can be selected depending on the purpose. That is, the carbide coating may consist essentially of metal carbide with the balance consisting of unavoidable impurities, or may contain a predetermined amount of sintering aid with the balance consisting of metal carbide and unavoidable impurities.

[0029] Examples of metal carbides include TaC, WC, NbC, ZrC, MoC, HfC, etc. The carbide coating may contain any one of these metal carbides, or may contain two or more of them. Among these, the metal carbide is preferably TaC or WC, because they are highly stable at high temperatures and are easily available.

[0030] The carbide coating according to the present invention is formed using a sintering method. In this case, a sintering aid is required to reduce the porosity of the coating. The type of sintering aid is selected optimally depending on the composition of the metal carbide. Examples of sintering aids include Ti, Cr, Fe, Co, and Ni. For example, when the metal carbide is TaC or WC, the sintering aid is preferably Co, because densification proceeds efficiently with the addition of a small amount.

[0031] For example, when Co is used as a sintering aid and a carbide coating is formed by sintering, a few mass% of Co is typically added to the raw material. However, depending on the manufacturing conditions, most of the Co may dissipate once densification is complete, leaving only traces of Co in the carbide coating. The amount of Co remaining in the carbide coating varies depending on the amount of Co added to the raw material and the sintering conditions. By optimizing the manufacturing conditions, a carbide coating containing 0.1 massppm to 100 massppm of Co, with the remainder consisting of metal carbide and unavoidable impurities (i.e., a carbide coating consisting essentially of metal carbide) can be obtained.

[0032] 1.2.5. Thickness The thickness of the carbide coating is not particularly limited, and an optimum value can be selected depending on the purpose. Generally, if the carbide coating is too thin, it will not be able to suppress corrosion of the substrate. Therefore, the thickness of the carbide coating is preferably 20 μm or more. The thickness is preferably 40 μm or more, and more preferably 60 μm or more. On the other hand, if the carbide coating is too thick, it becomes prone to peeling. Therefore, the thickness of the carbide coating is preferably 200 μm or less. The thickness is preferably 150 μm or less, and more preferably 100 μm or less.

[0033] [1.3. Characteristics] [1.3.1. Impurity film coverage] "Impurity film coverage (%)" refers to the ratio of the area (S2) of the impurity film attached to the surface of the carbide film to the area (S1) of the carbide film (=S2×100 / S1). The term "impurity film" refers to a film that adheres to the surface of the carbide film during the manufacture of the heat-resistant member or during use of the heat-resistant member. Examples of impurity films include: (a) When a carbide coating is formed using a sintering method, residues derived from the raw materials used for production adhere to the carbide coating during production (for example, pyrolytic carbon films derived from the organic binder used in forming the carbide coating), (b) Foreign matter (e.g., nitride-based semiconductor polycrystalline film, SiC semiconductor polycrystalline film, etc.) that adheres to the carbide coating during use of the heat-resistant component and originates from the process of use. etc.

[0034] For example, a pyrolytic carbon film can be a source of carbon impurities in the actual process in which the heat-resistant member is used. Furthermore, a polycrystalline film can be a source of particles being introduced into the surface of the growing crystal. Therefore, the smaller the coverage of the impurity film, the better. To prevent impurities from being introduced into the process in which the heat-resistant member is used, the coverage must be less than 3%. The coverage is preferably 2% or less, and more preferably 1% or less.

[0035] [1.3.2. Arithmetic mean roughness Ra] When an impurity film adheres to the surface of a carbide coating, the impurity film can be removed using mechanical removal methods such as polishing or ceramic blasting. However, when using mechanical removal methods, part of the surface of the carbide coating is scraped off at the same time as the impurity film is removed, which may increase the surface roughness of the carbide coating. The increase in surface roughness corresponds to the introduction of micro-defects into the carbide coating and may accelerate the deterioration of the carbide coating. Furthermore, the media used to remove the impurity film may remain on the surface of the carbide coating and become a source of contamination for processes in which the heat-resistant component is used.

[0036] In contrast, in the present invention, as described below, the impurity film on the carbide coating is removed by soft blasting, thereby suppressing an increase in surface roughness after the treatment. When the method described below is used, the arithmetic mean roughness Ra of the carbide coating becomes 1.5 μm or less.

[0037] [1.4. Purpose] The heat-resistant member according to the present invention can be used in various components exposed to high-temperature corrosive gases, such as crucibles for growing crystals or thin films of compound semiconductors, susceptors, heater materials, evaporation boats, and reflector materials. The heat-resistant member according to the present invention is particularly suitable as a susceptor for producing nitride-based semiconductors or SiC semiconductors.

[0038] [2. Carbide Coating Manufacturing Method] In the present invention, the carbide coating is produced by a sintering method. (a) applying a slurry containing a metal carbide powder to a surface of a substrate made of isotropic graphite and drying the slurry to form a molded film on the surface of the substrate; (c) The substrate on which the formed film is formed is heated in an inert atmosphere to sinter the formed film. It means a method.

[0039] [2.1. Molding process] First, a slurry containing metal carbide powder is applied to the surface of a substrate made of isotropic graphite, and then dried (forming step), thereby forming a formed film on the surface of the substrate.

[0040] The slurry is a raw material for forming a carbide coating. The formed film is a film that becomes a carbide coating after sintering. Generally, metal carbides are difficult to sinter, so in order to form a dense carbide coating, the slurry must contain an appropriate amount of sintering aid. The slurry also usually contains components (e.g., organic binders, dispersants, etc.) necessary to form a sound formed film.

[0041] The average particle size of the metal carbide powder, the type and amount of the sintering aid, the composition of the slurry, etc. are not particularly limited, and the optimum ones can be selected depending on the purpose. Generally, if the amount of sintering aid added to the slurry is too small, densification will not progress sufficiently, resulting in a large porosity. On the other hand, if the amount of sintering aid added is excessive, the sintering aid may remain in the carbide coating. The sintering aid remaining in the carbide coating may leak during use and become a source of contamination for the process in which the heat-resistant component is used. The suitable amount of sintering aid to be added varies depending on the type of sintering aid. For example, when the sintering aid is Co, the amount of sintering aid to be added is preferably 0.1 to 5 mass %.

[0042] When the carbide coating is made up of multiple layers with different compositions and / or microstructures, slurries with different compositions are used to form a laminate made up of multiple formed films.

[0043] 2.2. Sintering process Next, the substrate on which the formed film is formed is heated in an inert atmosphere to sinter the formed film (sintering step), which causes the formed film to become a dense carbide coating. The optimum sintering conditions are selected depending on the composition of the formed film. The optimum sintering conditions vary depending on the properties of the raw material powder and the composition of the slurry, but it is preferable to heat at 2000 to 2300°C for about 0.5 to 1.0 hour.

[0044] [3. Manufacturing method of heat-resistant components] The method for manufacturing a heat-resistant member according to the present invention includes the steps of: a first step of preparing a heat-resistant member precursor, the heat-resistant member precursor including a base material made of isotropic graphite, a carbide coating made of a sintered body containing metal carbide as a main component formed on all or part of the surface of the base material, and an impurity film attached to the surface of the carbide coating; a second step of subjecting the surface of the carbide coating to a blasting treatment in which soft media is collided with the surface to obtain the heat-resistant member according to the present invention; It is equipped with: The method for manufacturing a heat-resistant member may further include, after the second step, a third step of cleaning the heat-resistant member and removing any remaining media.

[0045] [3.1. 1st step] First, a heat-resistant member precursor is prepared (step 1), in which a carbide coating made of a sintered body containing metal carbide as a main component is formed on all or part of the surface of a substrate made of isotropic graphite, and an impurity film is further attached to the surface of the carbide coating.

[0046] The term "heat-resistant member precursor" refers to a member in which a carbide coating is formed on the surface of a substrate, and an impurity film is attached to the surface of the carbide coating. As described above, the "impurity film" refers to a film that adheres to the surface of the carbide film during the manufacture of the heat-resistant member or during use of the heat-resistant member.

[0047] The heat-resistant component according to the present invention is manufactured by a sintering method. Therefore, residues derived from the raw materials used for manufacturing the heat-resistant component may adhere to the surface of the heat-resistant component immediately after manufacturing. Examples of the residues include pyrolytic carbon films derived from the organic binder used in forming the carbide coating. The method according to the present invention can be used to remove such residues (i.e., for finishing the heat-resistant component). Details of the sintering method have been described above, so a detailed explanation will be omitted.

[0048] Alternatively, when the heat-resistant member according to the present invention is used in the manufacturing process of various materials, foreign matter resulting from the manufacturing process may adhere to the surface of the heat-resistant member after use. For example, when the heat-resistant member according to the present invention is used in the manufacturing process of a compound semiconductor single crystal, a polycrystalline film such as a nitride-based semiconductor polycrystalline film or a SiC semiconductor polycrystalline film may adhere to the surface of the carbide coating. The method according to the present invention can also be used to remove such foreign matter (i.e., to recycle the heat-resistant member). The use and conditions of use of the heat-resistant member are not particularly limited, and the optimum ones can be selected depending on the purpose.

[0049] [3.2. 2nd process] Next, a blasting treatment (soft blasting treatment) is carried out by colliding soft media against the surface of the carbide coating, to obtain the heat-resistant member according to the present invention (second step).

[0050] 3.2.1. Media [A. Materials] In the present invention, the media is made of a non-metallic material having a new Mohs hardness of 4 or less and a true specific gravity of 2.5 or less.

[0051] If the media hardness is too high, there is a risk of damaging the carbide coating during blasting. Therefore, the media must have a modified Mohs hardness of 4 or less. The modified Mohs hardness is preferably 3 or less, and more preferably 2.5 or less. Similarly, if the true specific gravity of the media is too high, it may damage the carbide coating during blasting. Therefore, the true specific gravity of the media must be 2.5 or less. The true specific gravity is preferably 2.2 or less, and more preferably 1.6 or less.

[0052] Furthermore, if media remains on the surface of the carbide coating after blasting, the remaining media may become a source of contamination when the heat-resistant component is used. Therefore, media that can be easily removed after blasting is preferred. In particular, media that can be removed by alkaline cleaning is preferred. Alternatively, media that do not require removal of remaining media after blasting is preferred. Media made of metallic materials not only have high hardness and / or true specific gravity, but also tend to be difficult to remove, so the media must be made of a non-metallic material.

[0053] Examples of media that meet the above conditions include: (a) Plastics such as nylon, polyester, urea resin, and melamine resin; (b) dry ice, (c) Corn, wheat, apricot seeds, peach seeds, walnut shells, baking soda, etc. The media may consist of any one of these, or may consist of two or more of these.

[0054] Among these, plastic has an appropriate hardness and true specific gravity, and can be easily removed by alkaline washing, making plastic suitable as a medium. Dry ice has the appropriate hardness and true specific gravity. Furthermore, the remaining dry ice sublimes after the blasting process, so there is no need to remove it. Therefore, dry ice is an ideal medium.

[0055] [B. Average particle size] "Average particle size" refers to the median particle size (d 50 ) The average particle size of the media affects the efficiency of impurity film removal and the performance of the carbide coating. If the average particle size of the media is too small, the efficiency of impurity film removal decreases. Therefore, the average particle size of the media is preferably 100 μm or more. The average particle size is preferably 200 μm or more. On the other hand, if the average particle size of the media is too large, even media with low hardness and low true specific gravity may damage the carbide coating. Therefore, the average particle size of the media is preferably 1 mm or less. The average particle size is more preferably 600 μm or less, and even more preferably 400 μm or less.

[0056] 3.2.2. Air pressure The air pressure during blasting affects the efficiency of impurity film removal and the performance of the carbide coating. If the air pressure during blasting is too low, the efficiency of impurity film removal decreases. Therefore, the air pressure is preferably 0.3 MPa or higher. The air pressure is preferably 0.4 MPa or higher. On the other hand, if the air pressure is too high, there is a risk of damaging the carbide coating even with media of low hardness and low true specific gravity. Therefore, the air pressure is preferably 1.0 MPa or less. The air pressure is preferably 0.8 MPa or less, and more preferably 0.6 MPa or less.

[0057] 3.2.3. Processing Time The optimum treatment time is selected depending on the composition of the impurity film, the type of media used, the air pressure, etc. For example, when the impurity film is a pyrolytic carbon film, the coverage can usually be reduced to less than 3% with treatment for about 1 to 20 minutes.

[0058] [3.3. Third step] Next, if necessary, the heat-resistant member is washed to remove the remaining media (third step).

[0059] For example, if dry ice is used as the medium, even if dry ice particles remain on the surface of the heat-resistant member after treatment, the remaining dry ice particles will eventually sublimate, making cleaning of the heat-resistant member unnecessary. On the other hand, when a plastic is used as the media, for example, plastic particles may adhere to the surface of the heat-resistant component after the treatment. Depending on the application of the heat-resistant component, the remaining plastic particles may become a source of contamination. In such cases, it is preferable to clean the heat-resistant component after the blast treatment to remove the remaining media.

[0060] The cleaning method is not particularly limited, and it is preferable to select an optimum method depending on the type of media. Examples of cleaning methods include alkaline cleaning, which dissolves the media in an alkaline solution, organic solvent cleaning, and water cleaning. Among these, alkaline cleaning is preferred as the cleaning method because it has a higher ability to dissolve and remove media than other methods.

[0061] [4. Effect] Sintering can form a dense carbide coating on the surface of a substrate. However, a pyrolytic carbon film resulting from the organic binder may remain as a residue on the carbide coating formed by sintering. The pyrolytic carbon film can be a source of carbon impurities in the actual process in which the heat-resistant component is used.

[0062] Pyrolytic carbon films are chemically stable and therefore difficult to remove by chemical cleaning or other methods. On the other hand, they can be removed by mechanical removal methods (e.g., grinding, ceramic blasting, etc.). However, mechanical removal methods have the risk of contaminating the surface of the carbide coating with abrasives or blasting media, or of the abrasives or blasting media damaging the coating.

[0063] In contrast, for heat-resistant components with a carbide coating formed on the substrate surface and an impurity film attached to the carbide coating surface, blasting (soft blasting) can be performed to remove the impurity film on the carbide coating easily and at low cost without damaging the carbide coating. Furthermore, soft media made of nonmetallic materials do not contaminate the carbide coating, or even if they do, they can be easily removed. Therefore, when the heat-resistant components obtained in this manner are used, for example, as susceptors in semiconductor film deposition processes, unintended contamination of impurities is prevented, and process reproducibility is expected to be improved.

[0064] Such a method is (a) Not only does it remove residues (such as pyrolytic carbon films) from the raw materials used in the manufacture of heat-resistant components that adhere to the surface of the carbide coating, but it also (b) Removal of foreign matter (e.g., nitride-based semiconductor polycrystalline film, SiC semiconductor polycrystalline film, etc.) that adheres to the surface of the carbide coating during use of the heat-resistant component and originates from the process of use. It can also be used for [Example]

[0065] (Examples 1 and 2, Comparative Examples 1 and 2) 1. Sample Preparation 1.1. Fabrication of heat-resistant components The substrate has an average CTE of 4.8 × 10 -6A plate of isotropic graphite (φ100×3 mm or □50×3 mm) with a porosity of 100 / K was used. WC powder with an average particle size of 1 to 3 μm, Co powder with an average particle size of 0.05 to 0.5 μm, and an organic binder were added to an organic solvent to obtain a slurry. The amount of Co powder added was 0.5 to 2.0 mass% of the mass of the formed film (after drying and before sintering). The slurry was spray-coated onto the surface of the substrate to form a formed film. The thickness of the formed film was set to a thickness that would result in a film thickness of 50 to 100 μm after sintering.

[0066] To remove the organic solvent contained in the film, the substrate with the film was heated on a hot plate at 150°C for 30 minutes. The substrate was then sintered at 2000°C for 1 hour in an inert atmosphere containing Ar, yielding a WC-coated graphite component. The Co content in the WC coating was less than 100 mass ppm.

[0067] [1.2. Blasting] The WC-coated graphite member was subjected to blasting treatment immediately after production using an air blasting device. The air pressure was 0.5 MPa. The following media were used: (a) Example 1: Dry ice (average particle size 0.3 mm, new Mohs hardness 2, true specific gravity 1.56), (b) Example 2: Nylon (average particle size 0.2 mm, new Mohs hardness 2, true specific gravity 1.15), (c) Comparative Example 1: Ceramics (alumina) (average particle size 0.3 mm, new Mohs hardness 12, true specific gravity 3.93), (d) Comparative Example 2: No blasting treatment.

[0068] 2. Test Method [2.1. Visual evaluation] Damage to the carbide coating (presence or absence of cracks and peeling) was evaluated visually. 2.2. Optical Microscope Evaluation The coverage rate (area fraction) of the pyrolytic carbon film and the presence or absence of minute damage (cracks and peeling) were evaluated. [2.3. Surface roughness evaluation] The arithmetic mean roughness (Ra) of the WC coating after blasting was evaluated using a contact surface roughness meter.

[0069] [3. Results] The results are shown in Table 1. Fig. 1(A) shows an optical microscope photograph of the carbide coating surface after blasting (Example 1). Fig. 1(B) shows an optical microscope photograph of the carbide coating surface before blasting (Comparative Example 2). The following can be seen from Table 1 and Fig. 1. (1) When blasting was not performed (Comparative Example 2), the WC coating did not crack or peel, and the Ra value was 1.1. However, the coverage of the pyrolytic carbon film was 3 to 90%. (2) When blasting was performed using ceramic media (Comparative Example 1), cracks and peeling of the WC coating were observed, so the Ra value was not measured. (3) When dry ice (Example 1) or nylon (Example 2) was used as the media, the WC coating did not crack or peel. The Ra values ​​for Examples 1 and 2 were 1.1 and 1.0, respectively. The coverage was less than 1% in both cases.

[0070] [Table 1]

[0071] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention. [Industrial Applicability]

[0072] The heat-resistant member according to the present invention can be used for a crucible for growing crystals or thin films made of compound semiconductors, a susceptor, a heater material, a deposition boat, a reflector material, and the like.

Claims

1. A heat-resistant member having the following configuration: (1) The heat-resistant member is a substrate made of isotropic graphite; a carbide coating formed on all or part of the surface of the substrate and made of a sintered body containing metal carbide as a main component; It is equipped with: however, The phrase "mainly composed of metal carbide" means that the content of the metal carbide in the carbide coating is 90 at % or more, The "content (at %) of metal carbide" refers to the ratio of the sum of the number of atoms of the metal element constituting the metal carbide and the number of carbon atoms to the total number of atoms contained in the carbide coating. (2) The coverage of the pyrolytic carbon film adhering to the surface of the carbide coating is 1% or less. However, the "coverage of the pyrolytic carbon film" refers to the area of ​​the carbide film (S 1 ) the area of ​​the pyrolytic carbon film attached to the surface of the carbide coating relative to the surface area (S 2 ) ratio (= S 2 ×100 / S 1 ) (3) The arithmetic mean roughness Ra of the carbide coating is 1.5 μm or less.

2. The heat-resistant member according to claim 1 , wherein the metal carbide comprises TaC or WC.

3. 3. The heat-resistant member according to claim 1, which is used as a susceptor for producing a nitride-based semiconductor or a SiC semiconductor.

4. A method for manufacturing a heat-resistant member comprising the following steps: (1) The method for manufacturing the heat-resistant member includes the steps of: a first step of preparing a heat-resistant member precursor, the heat-resistant member precursor including a base material made of isotropic graphite, a carbide coating made of a sintered body containing metal carbide as a main component formed on all or part of the surface of the base material, and a pyrolytic carbon film attached to the surface of the carbide coating; a second step of subjecting the surface of the carbide coating to a blasting treatment in which soft media is collided against the surface to obtain the heat-resistant member according to any one of claims 1 to 3; It is equipped with: (2) The media is made of a non-metallic material having a new Mohs hardness of 4 or less and a true specific gravity of 2.5 or less.

5. The method for manufacturing a heat-resistant member according to claim 4, wherein the medium is made of plastic or dry ice.

6. 6. The method for manufacturing a heat-resistant member according to claim 4, wherein the media has an average particle size of 100 [mu]m or more and 1 mm or less.

7. The method for manufacturing a heat-resistant member according to any one of claims 4 to 6, wherein the second step comprises performing the blasting treatment under an air pressure condition of 0.3 MPa or more and 1.0 MPa or less.

8. The method for manufacturing a heat-resistant member according to claim 4 , further comprising a third step of cleaning the heat-resistant member and removing any remaining media after the second step.

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