Silicon carbide sintered body and heat dissipation member

Abstract

To provide a silicon carbide sintered body having high thermal conductivity. [Solution] One embodiment of the present invention provides a silicon carbide sintered body containing sintered silicon carbide particles and a scandium compound, with a thermal conductivity of 275 W / m·K or more and a free carbon content of 0.1 wt% or less. The silicon carbide sintered body may have a volume resistivity of 5.0 Ω·cm or more. The silicon carbide sintered body may have a predominant crystalline phase of a 4H crystal structure. According to one embodiment of the present invention, a silicon carbide sintered body having high thermal conductivity and high resistivity can be provided.

Description

[Technical Field]

[0001] The present invention relates to a silicon carbide sintered body and a heat dissipation member. [Background technology]

[0002] Silicon carbide is widely used in various devices as a material for heat-resistant components such as heaters and power semiconductor components. Recently, active development of silicon carbide sintered bodies with high thermal conductivity has been underway. Non-Patent Document 1 discloses a silicon carbide sintered body with high thermal conductivity obtained by using a Be sintering additive. Patent Document 1 also discloses a silicon carbide sintered body that contains yttrium oxide and thereby exhibits a well-balanced improvement in the properties of electrical conductivity, thermal conductivity, and plasma resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6787207 [Non-patent literature]

[0004] [Non-Patent Document 1] Yukio Takeda, Kosuke Nakamura, Kunihiro Maeda, Yasuo Matsushita, Journal of the Ceramic Association 95 [9] 860-863 (1987) Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, the thermal conductivity of conventional silicon carbide sintered bodies is only 270 W / m·K at most. Furthermore, the BeO used in the silicon carbide sintered body of Non-Patent Document 1 is toxic, posing problems in terms of manufacturing and practical use. Furthermore, the volume resistivity of the body of Patent Document 1 is only 1.5 Ω·cm, meaning it cannot be used as a high-resistance (high-voltage) component.

[0006] In view of the above problems, one object of the present invention is to provide a silicon carbide sintered body having high thermal conductivity. [Means for solving the problem]

[0007] According to one embodiment of the present invention, there is provided a silicon carbide sintered body comprising sintered silicon carbide particles and a scandium compound, the silicon carbide sintered body having a thermal conductivity of 275 W / m·K or more and a free carbon content of 0.1 wt % or less.

[0008] The silicon carbide sintered body may have a volume resistivity of 5.0 Ω·cm or more.

[0009] In the silicon carbide sintered body, the main crystalline phase of the silicon carbide particles may have a 4H crystalline structure.

[0010] According to one embodiment of the present invention, there is provided a silicon carbide sintered body comprising sintered silicon carbide particles and a scandium compound, the silicon carbide sintered body having a nitrogen content of 300 ppm by weight or less and a free carbon content of 0.1% by weight or less.

[0011] In the silicon carbide sintered body, the arithmetic mean value of the major axis diameter of the silicon carbide particles in an arbitrary region of a polished surface of the silicon carbide sintered body may be 10 μm or more.

[0012] In the silicon carbide sintered body, the area-weighted average of the major axis diameter of the silicon carbide particles in an arbitrary region of a polished surface of the silicon carbide sintered body may be 30 μm or more.

[0013] In the silicon carbide sintered body, the maximum value of the major axis diameter of the silicon carbide particles in any region of a polished surface of the silicon carbide sintered body may be 70 μm or more.

[0014] In the silicon carbide sintered body, the arithmetic mean value of the particle area of ​​the silicon carbide particles in any region of the polished surface obtained by polishing the surface of the silicon carbide sintered body is 50 μm2 It may be more than that.

[0015] In the silicon carbide sintered body, the surface of the silicon carbide sintered body is polished, and the area-weighted average value of the particle area of ​​the silicon carbide particles in any region of the polished surface is 300 μm 2 It may be more than that.

[0016] In the silicon carbide sintered body, the maximum value of the particle area of ​​the silicon carbide particles in any region of the polished surface obtained by polishing the surface of the silicon carbide sintered body is 1000 μm 2 It may be more than that.

[0017] The silicon carbide sintered body may contain nitrogen in an amount of 300 ppm by weight or less.

[0018] According to one embodiment of the present invention, there is provided a heat dissipation member using a silicon carbide sintered body. [Effects of the Invention]

[0019] According to one embodiment of the present invention, it is possible to provide a silicon carbide sintered body having a higher thermal conductivity than conventional sintered bodies. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a scanning electron microscope image of the polished surface of the silicon carbide sintered body of Example 2. [Figure 2] 1 is a scanning electron microscope image of the polished surface of the silicon carbide sintered body of Comparative Example 1. [Figure 3] 1 is an EBSD image of the silicon carbide sintered body of Example 2. [Figure 4] 4 is an image obtained by crystal structure analysis of the EBSD image (FIG. 3) of the silicon carbide sintered body of Example 2. [Figure 5] 1 is an image showing an evaluation of the major axis diameter of silicon carbide particles in an EBSD image of the silicon carbide sintered body of Example 2. [Figure 6]1 is a graph showing the relationship between the arithmetic mean value of the major axis diameter of silicon carbide particles and the thermal conductivity of the silicon carbide sintered body in Examples 1 to 22 and Comparative Examples 1 to 6. [Figure 7] 1 is a graph showing the relationship between the arithmetic mean value of the area of ​​silicon carbide particles and the thermal conductivity of the silicon carbide sintered body in Examples 1 to 22 and Comparative Examples 1 to 6. DETAILED DESCRIPTION OF THE INVENTION

[0021] The following embodiments are examples of the present invention, and the present invention is not limited to these embodiments.

[0022] <1. Composition of sintered silicon carbide> The configuration of a silicon carbide sintered body according to one embodiment of the present invention will be described below.

[0023] A silicon carbide sintered body according to one embodiment of the present invention contains sintered silicon carbide particles and a scandium compound. The scandium compound is produced by the addition of a sintering aid and exists in the sintered body as particles or grain boundary phases. In addition to scandium and oxygen, nitrogen, silicon, carbon (free carbon), and other trace metal elements may be detected in these particles and grain boundary phases. The incorporation of oxygen, nitrogen, and other trace metal elements by the scandium compound reduces their solid solution in the silicon carbide particles and cleans the grain boundaries between the silicon carbide particles. It is well known that oxygen and nitrogen dissolved in silicon carbide form various lattice defects by substituting for carbon at the C-site of silicon carbide, thereby reducing thermal conductivity through phonon scattering.

[0024] The content of the scandium compound in the silicon carbide sintered body is 0.01 to 5.0 wt. % (equivalent to scandium oxide), preferably 0.1 to 3.0 wt. If it is less than 0.01 wt. %, the effect is insufficient and high thermal conductivity is not achieved. If it is more than 5.0 wt. %, in addition to suppressing the grain growth of silicon carbide particles, the presence of scandium compound particles with low thermal conductivity reduces the thermal conductivity of the silicon carbide sintered body.

[0025] Furthermore, the amount of nitrogen contained in the silicon carbide sintered body according to one embodiment of the present invention (also referred to as the nitrogen content or nitrogen concentration) is desirably 300 ppm by weight (or ppm by mass) or less, preferably 150 ppm by weight or less, more preferably 100 ppm by weight or less, and even more preferably 50 ppm by weight or less. Since nitrogen acts as a donor, reducing the nitrogen content can reduce the electrical conductivity of the silicon carbide sintered body (silicon carbide particles) and increase the volume resistivity. Furthermore, although the mechanism is currently unknown, the inclusion of a scandium compound, the low nitrogen content, and the low free carbon content cause the silicon carbide particles to preferentially form an α-type 4H crystal structure (4H-SiC) over a β-type 3C crystal structure (3C-SiC), resulting in large grain growth. Therefore, the silicon carbide sintered body according to one embodiment of the present invention is characterized by being composed of large silicon carbide particles whose main crystalline phase has a 4H crystal structure.

[0026] Furthermore, the amount of free carbon contained in the silicon carbide sintered body according to one embodiment of the present invention (also referred to as the free carbon content or free carbon concentration) is desirably 0.10% by weight or less, preferably 0.05% by weight or less, and more preferably 0.01% by weight or less. If the free carbon content is 0.10% by weight or more, not only will it hinder the grain growth of silicon carbide particles, but the free carbon particles precipitated at grain boundaries and the like will have strong anisotropy in thermal conductivity, which will reduce the thermal conductivity of the sintered body.

[0027] The size of the silicon carbide particles is calculated in a partial region of the polished surface of the silicon carbide sintered body. In one embodiment of the present invention, in any region of the polished surface (for example, at least one region of 400 μm × 400 μm), the arithmetic mean value of the major axis diameter of the silicon carbide particles is 10 μm or more, the area-weighted mean value of the major axis diameter of the silicon carbide particles is 30 μm or more, and the maximum value of the major axis diameter of the silicon carbide particles is 70 μm or more. Similarly, in the same region, the arithmetic mean value of the area of ​​the silicon carbide particles is 50 μm or more. 2 The area-weighted average value of the silicon carbide particle area is 300 μm or more. 2 The maximum area of ​​silicon carbide particles is 1000 μm 2 That's all.

[0028] The silicon carbide sintered body having the above-described configuration has a thermal conductivity of 275 W / m·K or more, and a volume resistivity of 5.0 Ω·cm or more.

[0029] <2. Manufacturing method of silicon carbide sintered body> A method for producing a silicon carbide sintered body according to one embodiment of the present invention will be described below. Note that the method for producing the silicon carbide sintered body is not particularly limited, and other well-known methods may be used.

[0030] (1) Preparation of silicon carbide powder First, silicon carbide powder to be used in the production of silicon carbide sintered bodies is prepared. In one embodiment of the present invention, the silicon carbide powder used in the silicon carbide sintered body should have a low metal impurity content, preferably substantially no metal impurities, from the viewpoint of high thermal conductivity. Furthermore, from the viewpoint of high resistivity and high thermal conductivity, the amount of nitrogen contained in the silicon carbide powder is desirably 500 weight ppm or less, preferably 300 weight ppm or less. This can promote the formation of an α-type 4H crystal structure (4H-SiC) rather than a β-type 3C crystal structure (3C-SiC) as the crystalline phase (crystal structure) of silicon carbide. Furthermore, the particle size of the silicon carbide powder is desirably about 0.1 to 20 μm, preferably about 0.3 to 5 μm, in terms of average particle size (D50).

[0031] (1-1) Synthesis / drying process A raw material containing a silicon source, a raw material containing a carbon source, and a raw material containing a catalyst are mixed in predetermined amounts to form a mixture. The mixture is then stirred and heated to make it homogeneous, and the mixture is reacted and dried to produce a solid.

[0032] The silicon source may be liquid or solid, but preferably contains a liquid silicon source. Liquid silicon sources are not particularly limited, but examples include alkoxysilane compounds, ethyl silicates, and alkoxysilane oligomers. Solid silicon sources are not particularly limited, but examples include silicon oxides such as silicon monoxide (SiO) and silicon dioxide (SiO), and metallic Si.

[0033] A resin material can be used as the carbon source. In this example, a phenolic resin is used. The phenolic resin is preferably a high-purity resin with impurity elements of 20 ppm by weight or less (more preferably 5 ppm by weight or less, and even more preferably 0.5 ppm by weight or less). (The impurity elements refer to elements belonging to Groups 1 to 16 of the Periodic Table of the 1989 IUPAC Nomenclature System and having atomic numbers 3 or greater (excluding atomic numbers 6 to 8 and 14).) The phenolic resin may be in either liquid or solid form. In the case of a solid form, it is preferable to dissolve it in an appropriate solvent before use. Furthermore, novolac-type phenolic resins may be used because they are easily manufactured without using nitrogen compounds. Compared to resol-type phenolic resins, novolac-type phenolic resins can reduce the amount of nitrogen.

[0034] The catalyst is not particularly limited, but examples thereof include maleic acid, p-toluenesulfonic acid, acetic acid, acrylic acid, oxalic acid, malonic acid, and succinic acid. Furthermore, in this embodiment, pure water may be added as a reactant. When ethyl silicate or alkoxysilane is used as the silicon source, adding pure water promotes hydrolysis and polymerization, thereby promoting the reaction.

[0035] (1-2) Carbonization process Next, the solid material is heated to 500 to 1000° C. in a non-oxidizing atmosphere such as argon, thereby producing a carbide.

[0036] (1-3) Firing process Next, the carbide is heated in a non-oxidizing atmosphere to 1700 to 2000° C. This produces silicon carbide coarse particles.

[0037] (1-4) Crushing process Next, the silicon carbide coarse particles are pulverized. This produces silicon carbide powder. The pulverization method is not particularly limited, but in this example, a pulverization method using a dry jet mill can be applied. When pulverized using a dry jet mill, it is desirable that the nitrogen content of the silicon carbide powder be 500 weight ppm or less, preferably 300 weight ppm or less. In this case, it is desirable that the particle size of the pulverized silicon carbide powder be an average particle size (D50) of about 0.1 to 20 μm, preferably about 0.3 to 5 μm.

[0038] (2) Granulation process Next, the silicon carbide powder, the sintering aid, and the dispersion medium are mixed to prepare a liquid mixture (slurry), which is then subjected to a granulation process.

[0039] Silicon carbide is a difficult-to-sinter material, and conventional raw materials contain a large amount of impurities such as oxygen, making the use of sintering aids, such as carbon, essential. However, it is known that some of these sintering aids remain in the sintered body after sintering, causing a decrease in the thermal and mechanical properties of the sintered body. Therefore, the less sintering aids used, the better, and ideally, no sintering aids would be used at all.

[0040] When carbon is used as the sintering aid, a carbon-based material such as a resol-type phenolic resin or a novolac-type phenolic resin can be used as the carbon source, and the use of a novolac-type phenolic resin is particularly preferred because it can suppress an increase in the amount of nitrogen. Note that the carbon-based material aid does not necessarily have to be used in order to reduce the content of free carbon in the silicon carbide sintered body.

[0041] As the metal compound sintering aid, a scandium compound, more specifically scandium oxide, is used. The amount of the scandium compound blended is 0.01 to 5.0 wt %, preferably 0.1 to 3.0 wt %. By using a metal compound as a sintering aid, the sintering temperature can be lowered compared to when only a carbon-based sintering aid is used.

[0042] In one embodiment of the present invention, the granulation method is not particularly limited, but spray granulation (spray drying), fluidized bed granulation, tumbling granulation, etc. can be used. The size of the silicon carbide granules after granulation is preferably an average particle size (D50) of 0.5 to 150 μm, preferably about 30 to 150 μm. In this case, by granulating using spray granulation (spray drying), it is possible to produce silicon carbide granules that are easy to handle while uniformly dispersing the sintering aid.

[0043] (3) Sintering process Next, the granulated silicon carbide particles are sintered. The sintering method is not particularly limited, but hot pressing, reaction sintering, atmospheric sintering, etc. can be used. For example, hot pressing is preferred because it can improve the density of the silicon carbide sintered body after sintering. The maximum temperature in the hot pressing method is not particularly limited, but is preferably 1900 to 2400°C, and preferably 2000 to 2300°C. The pressure in the hot pressing is not particularly limited, but may be 20 to 50 MPa.

[0044] <3.Applications> The silicon carbide sintered body according to one embodiment of the present invention can be used for semiconductor manufacturing equipment components such as, but not limited to, heat dissipation components, susceptors (wafer support components), susceptor covers (components for protecting the wafer support components), heaters, rings, electrodes, and sputtering targets.

[0045] <Modification> The present disclosure is not limited to the above-described embodiments and includes various other modifications. For example, the above-described embodiments have been described in detail to clearly explain the present disclosure, and are not necessarily limited to those including all of the described configurations. Furthermore, part of the configuration of one embodiment may be replaced with the configuration of another embodiment, or the configuration of another embodiment may be added to the configuration of one embodiment. Furthermore, part of the configuration of each embodiment may be added to, deleted from, or replaced with another configuration. Some modifications will be described below.

[0046] In one embodiment of the present invention, the silicon carbide sintered body contains silicon carbide particles and a scandium compound, but the present invention is not limited thereto. For example, in addition to the sintered silicon carbide particles and scandium compound, the sintered body may contain rare earth metal compounds such as yttrium compounds, ytterbium compounds, and lanthanum compounds, or transition metal compounds such as vanadium compounds, chromium compounds, and tantalum compounds. In this case, the total content of the metal compounds including the scandium compound is desirably 0.01 to 5.0 wt%, preferably 0.1 to 3.0 wt%.

[0047] In one embodiment of the present invention, the phrase "the silicon carbide sintered body contains silicon carbide particles and a scandium compound" encompasses the phrase "contains silicon carbide particles and scandium oxide." This takes into account the possibility that the composition of the scandium oxide mixed during sintering may change slightly due to volatilization, etc. In this case, the scandium compound may include scandium nitride, scandium oxynitride, or scandium carbide in addition to scandium oxide. Similarly, as rare earth metal compounds, yttrium compounds may include yttrium oxide, yttrium nitride, yttrium oxynitride, or yttrium carbide; ytterbium compounds may include ytterbium oxide, ytterbium nitride, ytterbium oxynitride, or ytterbium carbide; lanthanum compounds may include lanthanum oxide, lanthanum nitride, lanthanum oxynitride, or lanthanum carbide; and other rare earth and transition metal compounds may include oxides, nitrides, oxynitrides, or carbides. [Example]

[0048] Next, examples embodying the present invention will be described in comparison with comparative examples. Note that the materials, quantities, and conditions of each part in the examples are merely examples and can be changed as appropriate without departing from the scope of the invention.

[0049] 1. Evaluation Method In the present examples, the evaluation methods for the silicon carbide sintered bodies produced under each condition will be described below.

[0050] (1) Volume resistivity evaluation The volume resistivity was evaluated using a resistivity meter (Loresta GP MCP-T610, manufactured by Nitto Seiko Analytech Co., Ltd.).

[0051] (2) Thermal conductivity evaluation The thermal conductivity was evaluated using a thermal conductivity measuring device (LFA467 HyperFlash, manufactured by NETZSCH).

[0052] (3) Composition analysis of sintered body The composition of the sintered body was analyzed using a wavelength dispersive X-ray fluorescence analyzer (ZSX Primus IV, manufactured by Rigaku Corporation). The amount of each component in the sintered body was quantified in EZ scan mode, and the amount of contained scandium compounds was expressed as a weight ratio to silicon carbide by converting the metal component into oxide (Sc2O3).

[0053] (4) Nitrogen content evaluation The nitrogen amount was evaluated using a nitrogen analyzer (EMGA-Expert, manufactured by Horiba, Ltd.).

[0054] (5) Crystal structure evaluation An X-ray diffractometer (Ultima IV, Rigaku Corporation) was used to evaluate the crystal structure. Quantification of each polytype was performed by measuring the intensity of each diffraction line in the X-ray diffraction and using regression analysis. Microscopic crystal structure evaluation was performed using electron backscatter diffraction (EBSD) with a scanning electron microscope (JSM-IT700HR, JEOL Ltd.).

[0055] (6) Particle size and particle area evaluation The particle size of the prepared silicon carbide powder was evaluated using a particle size distribution analyzer (LS-13-320, manufactured by Beckman Coulter). A scanning electron microscope was used to evaluate the particle size and particle area of ​​the silicon carbide sintered body. Electron backscatter diffraction (EBSD) was used as the evaluation condition for evaluating the particle size and particle area of ​​the silicon carbide sintered body. The major axis diameter (arithmetic mean, area-weighted mean, maximum value) and area (arithmetic mean, area-weighted mean, maximum value) of the crystal grains were calculated in the region where the total number of particles was 50 or more, for example, a 400 μm × 400 μm region for Examples 1, 2, 4 to 14, 16, 17, 20, 21 and Comparative Example 3, a 1000 μm × 1000 μm region for Examples 3, 15, 18, 19, 22, and a 60 μm × 60 μm region for Comparative Examples 1, 2, 4, 5, and 6.

[0056] (7) Free carbon content The free carbon content was measured using a carbon analyzer (EMIA-810W, manufactured by Horiba, Ltd.).

[0057] 2. Preparation of Sintered Silicon Carbide The conditions for producing the silicon carbide sintered body under each condition will be explained below with reference to Table 1.

[0058] [Table 1]

[0059] [Example 1] The method for producing the silicon carbide sintered body of Example 1 will be described below.

[0060] (1) Preparation of silicon carbide powder (1-1) Synthesis and drying process Liquid ethyl silicate oligomer (Ethyl Silicate 40, 40% SiO2 by weight, manufactured by Colcoat Co., Ltd.) was used as the silicon source. Solid novolac phenolic resin (PR-56431, manufactured by Sumitomo Bakelite Co., Ltd.) was used as the carbon source. Liquid maleic acid aqueous solution (produced by Nippon Shokubai Co., Ltd., obtained by hydrolyzing and dissolving maleic anhydride in purified water) was used as the catalyst. 24% by weight of ethanol and 16% by weight of novolac phenolic resin were placed in a container and stirred to dissolve the novolac phenolic resin in ethanol. 51% by weight of ethyl silicate 40, 8% by weight of maleic acid aqueous solution, and 1% by weight of purified water were then added and mixed to form a viscous mixture. The mixture was gradually heated from room temperature to 200°C, reacted, and dried to obtain a lumpy solid.

[0061] (1-2) Carbonization Next, the solid was heated at 900° C. for 2 hours in an argon atmosphere to obtain a carbide mass.

[0062] (1-3) Firing treatment Next, the carbide was heated to 1900° C. in an argon atmosphere and held at that temperature for 4 hours to obtain silicon carbide coarse particles having particle sizes of approximately several tens of μm.

[0063] (1-4) Crushing Next, the silicon carbide coarse particles were pulverized in a dry jet mill, thereby producing silicon carbide powder having a nitrogen content of 34 ppm by weight and an average particle size (D50) of 0.84 μm.

[0064] (2) Granulation process Next, 19.90 g of the silicon carbide powder, 0.050 g (0.25 wt%) of scandium oxide (Sc2O3), and 0.050 g (0.25 wt%) of yttrium oxide (YO3) were mixed into a container, and then 0.525 g (2.6 wt%) of phenolic resin and 14 g of ethanol as a dispersion medium were added and mixed to obtain a liquid mixture (slurry). The slurry was then stirred and dried, and then passed through a sieve with 200 μm openings to obtain granulated powder.

[0065] (3) Sintering process Next, the obtained granulated powder was placed in a graphite mold and sandwiched between graphite punches, and then pressurized at a pressure of 40 MPa using a hot press device. The temperature was raised to 1600°C under vacuum conditions, and then further raised to 2200°C in an argon atmosphere and held at this temperature for 4 hours (hot press) to obtain a silicon carbide sintered body.

[0066] [Example 2] In Example 2, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide and yttrium oxide was changed (a mixture was prepared so that the compounding amount of silicon carbide powder was 19.90 g, the compounding amount of scandium oxide was 0.075 g (0.375 wt%), and the compounding amount of yttrium oxide was 0.025 g (0.125 wt%)).

[0067] [Example 3] In Example 3, a silicon carbide sintered body was obtained in the same manner as in Example 2, except that silicon carbide powder having a nitrogen content of 31 ppm by weight and an average particle size (D50) of 2.3 μm was used.

[0068] [Example 4] In Example 4, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide to yttrium oxide was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.23 wt % and the compounding amount of yttrium oxide was 0.85 wt %).

[0069] [Example 5] In Example 5, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide to yttrium oxide was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.225 wt % and the compounding amount of yttrium oxide was 0.075 wt %).

[0070] [Example 6] In Example 6, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide to yttrium oxide was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.525 wt % and the compounding amount of yttrium oxide was 0.175 wt %).

[0071] [Example 7] In Example 7, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide to yttrium oxide was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.75 wt % and the compounding amount of yttrium oxide was 0.25 wt %).

[0072] [Example 8] In Example 8, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide, yttrium oxide, and phenolic resin was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.375 wt %, the compounding amount of yttrium oxide was 0.125 wt %, and the compounding amount of phenolic resin was 1.0 wt %).

[0073] [Example 9] In Example 9, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide and yttrium oxide was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.375 wt % and the compounding amount of yttrium oxide was 0.125 wt %) and that no phenolic resin was included.

[0074] [Example 10] In Example 10, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide and yttrium oxide was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.525 wt % and the compounding amount of yttrium oxide was 0.175 wt %) and that no phenolic resin was included.

[0075] [Example 11] In Example 11, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratio of scandium oxide and yttrium oxide was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.75 wt % and the compounding amount of yttrium oxide was 0.25 wt %) and that no phenol resin was included.

[0076] [Example 12] In Example 12, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the mixture was prepared so that the blending amount of scandium oxide was 0.375 wt % and the blending amount of ytterbium oxide (Yb2O3) was 0.125 wt %.

[0077] [Example 13] In Example 13, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the mixture was prepared so that the blending amount of scandium oxide was 0.375 wt % and the blending amount of lanthanum oxide (La2O3) was 0.125 wt %.

[0078] [Example 14] In Example 14, a mixture was prepared so that the blending amount of scandium oxide was 0.5 wt %, and a silicon carbide sintered body was obtained in the same manner as in Example 1, except that no other metal oxides were contained.

[0079] [Example 15] In Example 15, a silicon carbide sintered body was obtained in the same manner as in Example 3, except that the phenol resin was not contained.

[0080] [Example 16] In Example 16, a silicon carbide sintered body was obtained in the same manner as in Example 15, except that the compounding ratio of scandium oxide and yttrium oxide was changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.15 wt % and the compounding amount of yttrium oxide was 0.05 wt %).

[0081] [Example 17] In Example 17, a silicon carbide sintered body was obtained in the same manner as in Example 15, except that the compounding ratio of scandium oxide and yttrium oxide was changed (the mixture was prepared so that the compounding amount of scandium oxide was 0.10 wt % and the compounding amount of yttrium oxide was 0.30 wt %).

[0082] [Example 18] In Example 18, a silicon carbide sintered body was obtained in the same manner as in Example 15, except that the compounding ratio of scandium oxide and yttrium oxide was changed (the mixture was prepared so that the compounding amount of scandium oxide was 0.30 wt % and the compounding amount of yttrium oxide was 0.10 wt %).

[0083] [Example 19] In Example 19, a silicon carbide sintered body was obtained in the same manner as in Example 15, except that the mixture was adjusted so that the blending amount of scandium oxide was 0.30 wt % and no other metal oxides were contained.

[0084] [Example 20] In Example 20, a silicon carbide sintered body was obtained in the same manner as in Example 15, except that a silicon carbide powder having a nitrogen content of 320 ppm by weight was used, the mixture was adjusted so that the scandium oxide content was 1.0% by weight, and 0.10% by weight of tantalum carbide was included.

[0085] [Example 21] In Example 21, a mixture was prepared so that the blending amount of scandium oxide was 3.0 wt %, and a silicon carbide sintered body was obtained in the same manner as in Example 15, except that no other metal oxides were contained.

[0086] [Example 22] In Example 22, a silicon carbide sintered body was obtained in the same manner as in Example 15, except that 0.05% by weight of vanadium carbide was contained as the other metal compound.

[0087] [Comparative Example 1] In Comparative Example 1, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that a pre-prepared silicon carbide powder with a nitrogen content of 1100 ppm by weight was used, scandium oxide and yttrium oxide were not contained, the amount of phenolic resin was adjusted to 9.5% by weight, and the maximum sintering temperature was set to 2300°C.

[0088] Comparative Example 2 In Comparative Example 2, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that scandium oxide and yttrium oxide were not included, the amount of phenolic resin was adjusted to 9.5 wt %, and the maximum sintering temperature was set to 2300°C.

[0089] Comparative Example 3 In Comparative Example 3, a mixture was prepared so that the blending amount of yttrium oxide was 0.5 wt %, and a silicon carbide sintered body was obtained in the same manner as in Example 1, except that no other metal oxides were contained.

[0090] Comparative Example 4 In Comparative Example 4, a silicon carbide sintered body was obtained in the same manner as in Example 2, except that a silicon carbide powder prepared in advance and having a nitrogen content of 430 ppm by weight was used.

[0091] Comparative Example 5 In Comparative Example 5, a silicon carbide sintered body was obtained in the same manner as in Example 2, except that a silicon carbide powder prepared in advance and having a nitrogen content of 1100 ppm by weight was used.

[0092] Comparative Example 6 In Comparative Example 6, a silicon carbide sintered body was obtained in the same manner as in Example 1, except that the compounding ratios of scandium oxide, yttrium oxide, and phenolic resin were changed (a mixture was prepared so that the compounding amount of scandium oxide was 0.375 wt %, the compounding amount of yttrium oxide was 0.10 wt %, and the compounding amount of phenolic resin was 9.5 wt %).

[0093] 3. Evaluation Results The evaluation results obtained under each condition are explained with reference to Table 2 and FIGS.

[0094] [Table 2]

[0095] (1) Scandium content According to Table 2, the amount of scandium compound contained in the silicon carbide sintered bodies in Comparative Examples 1 to 6 was 0 to 0.35 wt % in terms of oxide (Sc2O3), while the amount of scandium compound contained in the silicon carbide sintered bodies in Examples 1 to 22 was 0.04 to 2.93 wt % in terms of oxide (Sc2O3).

[0096] (2)Nitrogen content According to Table 2, the nitrogen content of the silicon carbide sintered bodies in Comparative Examples 1 to 6 was 34 to 860 ppm by weight, while the nitrogen content of the silicon carbide sintered bodies in Examples 1 to 22 was 19 to 281 ppm by weight.

[0097] (3) Free carbon content According to Table 2, the free carbon content of the silicon carbide sintered bodies in Comparative Examples 1 to 6 was 0.04 to 1.26 wt %, while the free carbon content of the silicon carbide sintered bodies in Examples 1 to 22 was less than 0.01 to 0.09 wt %.

[0098] (4) Crystal structure FIG. 1 is a scanning electron microscope (SEM) image of the polished surface of the silicon carbide sintered body of Example 2. FIG. 2 is an SEM image of the polished surface of the silicon carbide sintered body of Comparative Example 1. As shown in FIG. 1, it was confirmed that the silicon carbide crystal grains had grown large in the silicon carbide sintered body of Example 2. At this time, the boundaries (grain boundaries) of the crystal grains were in a very clean state, with almost no impurity components other than silicon carbide detected, and it was confirmed that the gaps and the auxiliary phase containing scandium were concentrated at the triple points. On the other hand, as shown in FIG. 2, in the silicon carbide sintered body of Comparative Example 1, large crystal grains like those in Example 2 were not confirmed. It was also confirmed that the gaps in Comparative Example 1 were smaller than those in Example 2 and were dispersed throughout.

[0099] FIG. 3 is an EBSD image of the silicon carbide sintered body of Example 2. FIG. 4 is the result of crystal structure analysis of the EBSD image of the silicon carbide sintered body of Example 2. As shown in FIG. 4, it was confirmed that the main crystalline phase of the silicon carbide sintered body of Example 2 was composed of an α-type 4H crystalline structure (4H—SiC). Furthermore, as shown in Table 2, according to the evaluation results by X-ray diffraction (XRD), it was confirmed that the main crystalline phase of the silicon carbide in Comparative Examples 1 to 6 included any one of a cubic 3C crystalline structure (3C—SiC), a hexagonal 6H crystalline structure (6H—SiC), or a hexagonal 4H crystalline structure (4H—SiC), whereas the main crystalline structure of Examples 1 to 22 was all composed of a hexagonal 4H crystalline structure (4H—SiC).

[0100] (5) Particle size / particle area Figure 5 is an image obtained when the major axis diameter of silicon carbide particles was evaluated using the EBSD image of Figure 3. According to Table 2, the arithmetic mean value of the major axis diameter of the silicon carbide particles in the silicon carbide sintered bodies of Comparative Examples 1 to 6 was 1.9 to 4.3 μm, the area-weighted mean value was 3.0 to 13 μm, and the maximum value was 7.2 to 51 μm, while the arithmetic mean value of the major axis diameter of the silicon carbide particles in the silicon carbide sintered bodies of Examples 1 to 22 was 16 to 120 μm, the area-weighted mean value was 38 to 361 μm, and the maximum value was 103 to 950 μm.

[0101] The area of ​​the silicon carbide particles was evaluated using EBSD images. According to Table 2, the arithmetic mean values ​​of the areas of the silicon carbide particles in the silicon carbide sintered bodies of Comparative Examples 1 to 6 were 1.6 to 7.4 μm 2 , area-weighted average value is 4.0 to 66 μm 2 , maximum value is 20 to 333 μm 2 In contrast, the arithmetic mean values ​​of the areas of the silicon carbide particles in the silicon carbide sintered bodies of Examples 1 to 22 were 87 to 5682 μm 2 , area-weighted average value is 352~66678μm 2 , maximum value is 1408~263455μm 2 It was.

[0102] From the above results, it was confirmed that the silicon carbide particles of Examples 1 to 22 were larger than those of Comparative Examples 1 to 6.

[0103] (6) Thermal conductivity According to Table 2, the thermal conductivities of Comparative Examples 1 to 6 were 210 to 249 W / m K. On the other hand, the thermal conductivities of Examples 1 to 22 were 276 to 383 W / m K, and it was confirmed that all Examples exhibited higher thermal conductivities than Comparative Examples 1 to 6.

[0104] FIG. 6 is a graph showing the relationship between the arithmetic mean value of the major axis diameter of silicon carbide particles and the thermal conductivity of silicon carbide sintered bodies in Examples 1 to 22 and Comparative Examples 1 to 6. FIG. 7 is a graph showing the relationship between the arithmetic mean value of the area of ​​silicon carbide particles and the thermal conductivity of silicon carbide sintered bodies in Examples 1 to 22 and Comparative Examples 1 to 6. As shown in FIGS. 6 and 7, it was confirmed that the thermal conductivity increases as the major axis diameter and area of ​​the silicon carbide particles increase. It is believed that the increase in the size of the silicon carbide particles in the silicon carbide sintered body as in Examples 1 to 22 promotes thermal conduction and improves the thermal conductivity of the silicon carbide sintered body as a whole. It was also confirmed that when a scandium compound is not contained as in Comparative Examples 1, 2, and 3, when the amount of nitrogen in the silicon carbide sintered body is high as in Comparative Examples 1, 4, and 5, or when the free carbon content is high as in Comparative Examples 1, 2, and 6, the silicon carbide particles do not grow, and the thermal conductivity of the silicon carbide sintered body tends to decrease.

[0105] (7) Volume resistivity According to Table 2, the volume resistivity of the silicon carbide sintered bodies of Comparative Examples 1 to 6 was 2.0 × 10 -2 ~6.7×10 2 On the other hand, the volume resistivity of the silicon carbide sintered bodies of Examples 1 to 22 was 5.4 × 10 0 ~1.9×10 7 The resistance was Ω·cm.

[0106] From the above, it has been confirmed that by using one embodiment of the present invention, a silicon carbide sintered body having high thermal conductivity can be obtained. It has also been confirmed that by using one embodiment of the present invention, a silicon carbide sintered body having both high thermal conductivity and high volume resistivity can be obtained.

[0107] In the above examples and comparative examples, scandium oxide was used as the scandium source to be blended when producing the silicon carbide sintered body of the present invention. However, the present invention is not limited to this, and scandium metal or a scandium-containing compound such as scandium carbonate or scandium nitride may also be used.

Claims

1. The sintered silicon carbide powder contains sintered silicon carbide particles and a scandium compound, and the nitrogen content is 300 ppm by weight or less. The free carbon content is 0.1% by weight or less, The silicon carbide particles have a predominant crystalline phase of 4H crystalline structure. Sintered silicon carbide.

2. The volume resistivity is 5.0 Ω cm or more. The silicon carbide sintered body according to claim 1.

3. In any region of the polished surface obtained by polishing the surface of the silicon carbide sintered body, the arithmetic mean value of the major axis diameter of the silicon carbide particles is 10 μm or more; The silicon carbide sintered body according to claim 1.

4. In any region of the polished surface obtained by polishing the surface of the silicon carbide sintered body, the area-weighted average value of the major axis diameter of the silicon carbide particles is 30 μm or more. The silicon carbide sintered body according to claim 1.

5. In any region of the polished surface obtained by polishing the surface of the silicon carbide sintered body, the maximum value of the major axis diameter of the silicon carbide particles is 70 μm or more. The silicon carbide sintered body according to claim 1.

6. In any region of the polished surface obtained by polishing the surface of the silicon carbide sintered body, the arithmetic mean value of the particle area of ​​the silicon carbide particles is 50 μm ２ That's all. The silicon carbide sintered body according to claim 1.

7. In any region of the polished surface obtained by polishing the surface of the silicon carbide sintered body, the area-weighted average value of the particle area of ​​the silicon carbide particles is 300 μm ２ That's all. The silicon carbide sintered body according to claim 1.

8. In any region of the polished surface obtained by polishing the surface of the silicon carbide sintered body, the maximum value of the particle area of ​​the silicon carbide particles is 1000 μm ２ That's all. The silicon carbide sintered body according to claim 1.

9. A heat dissipation member using the silicon carbide sintered body according to any one of claims 1 to 8.

Images