A polycrystalline SiC compact and a method for manufacturing the same

Abstract

The present invention provides a polycrystalline SiC compact having a resistivity of 0.050 Ωcm or less, the intensity of a diffraction peak in the range of diffraction angle 2θ of 33° to 34° in an X-ray diffraction pattern being "A", the intensity of a diffraction peak of the SiC (111) plane in the X-ray diffraction pattern being "B", and the ratio (A / B) being 0.018 or less.

Description

Technical Field

[0001] The present invention relates to a polycrystalline SiC compact and a method for manufacturing the same. Background Art

[0002] SiC compacts are excellent in various properties such as heat resistance, corrosion resistance, and strength, and are used for various applications. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-316821) and Patent Document 2 (Japanese Patent Application Laid-Open No. 2001-220237) disclose that SiC is used as components for plasma etching apparatuses such as edge rings, electrode plates, and heaters used in the manufacture of semiconductors. In addition, Patent Document 3 (Japanese Patent No. 6387375) discloses a semiconductor substrate having a single-crystalline SiC substrate and a polycrystalline SiC substrate, wherein the single-crystalline SiC substrate and the polycrystalline SiC substrate are joined through a predetermined interface layer.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-316821

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-220237

[0007] Patent Document 3: Japanese Patent No. 6387375. Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] For polycrystalline SiC compacts, various properties are required depending on the application.

[0010] For example, as described in Patent Documents 1 and 2, when a polycrystalline SiC compact is used as a component for plasma etching, in order to release static electricity or uniformly generate plasma gas, the polycrystalline SiC compact must have a low resistance. In addition, in order to uniformly process a silicon wafer with plasma, the distance between the polycrystalline SiC compact and the silicon wafer must be equal, which requires the polycrystalline SiC compact used as a component for a plasma etching apparatus to have a flat surface.

[0011] Moreover, as described in Patent Document 3, in order to join a polycrystalline SiC compact and a single-crystalline SiC substrate, the polycrystalline SiC compact must have a flat joining surface. In addition, when used for an application such as forming a current path across the joining surface of a polycrystalline SiC compact and a single-crystalline SiC substrate, the polycrystalline SiC compact may be required to have a low resistance.

[0012] Therefore, an object of the present invention is to provide a polycrystalline SiC compact having excellent low resistance and flatness and a method for manufacturing the same.

[0013] Means for Solving the Problem

[0014] To solve the above problems, the present invention includes the following aspects. [1]

[0016] A polycrystalline SiC compact, wherein

[0017] the resistivity of the polycrystalline SiC compact is 0.050 Ωcm or less,

[0018] in the X-ray diffraction pattern, the diffraction peak intensity in the range of diffraction angle 2θ of 33° to 34° is "A",

[0019] in the X-ray diffraction pattern, the diffraction peak intensity of the SiC (111) plane is "B",

[0020] the ratio (A / B) is 0.018 or less. [2]

[0022] The polycrystalline SiC compact according to [1], wherein the nitrogen content is 200 ppm (parts per million by mass) or more. [3]

[0024] The polycrystalline SiC compact according to [1] or [2], wherein the diffraction peak intensity B of the SiC (111) plane is the diffraction peak intensity in the range of diffraction angle 2θ of 35° to 36°. [4]

[0026] A method for manufacturing a polycrystalline SiC compact, which manufactures a polycrystalline SiC compact by CVD method, and the method includes:

[0027] An initial process of forming a first polycrystalline SiC film on a substrate at a raw material gas concentration of a first concentration;

[0028] A final process of forming a second polycrystalline SiC film on the first polycrystalline SiC film at a raw material gas concentration of a second concentration lower than the first concentration after the initial process. [5]

[0030] The method for manufacturing a polycrystalline SiC compact according to [4], wherein the first concentration is 1.2 to 2.0 times the second concentration. [6]

[0032] The method for manufacturing a polycrystalline SiC compact according to [4] or [5], wherein the time period of the initial process is 10% to 50% of the total time period of the film formation period of the polycrystalline SiC film. [7]

[0034] The manufacturing method of the polycrystalline SiC compact according to any one of [4] to [6], wherein between the initial process and the final process, the method further includes:

[0035] A middle process of reducing the raw material gas concentration from the first concentration to the second concentration and forming a third polycrystalline SiC film on the first polycrystalline SiC film. [8]

[0037] The manufacturing method of the polycrystalline SiC compact according to [7], wherein the middle process includes a process of reducing the raw material gas concentration at a fixed speed. [9]

[0039] The manufacturing method of the polycrystalline SiC compact according to [7] or [8], wherein the time period of the middle process is 10% to 50% of the overall time period of the film formation period of the polycrystalline SiC film, and the time period of the final process is not 0%.

[0040] Advantages of the Invention

[0041] The present invention can provide a polycrystalline SiC compact with excellent flatness and low resistance and a manufacturing method thereof. Brief Description of the Drawings

[0042] Figure 1 is a schematic cross-sectional view showing a laminated SiC substrate of an embodiment;

[0043] Figure 2A is a schematic cross-sectional view showing a manufacturing method of a laminated SiC substrate;

[0044] Figure 2B is a schematic cross-sectional view showing a manufacturing method of a laminated SiC substrate;

[0045] Figure 3 is a schematic diagram showing an example of a manufacturing system used in the manufacturing method of a polycrystalline SiC substrate;

[0046] Figure 4 is a graph conceptually showing the relationship between the time during film formation and the raw material gas concentration;

[0047] Figure 5A is a schematic cross-sectional view showing a radial cross-section of a graphite substrate 2 having a polycrystalline SiC film 4 formed thereon;

[0048] Figure 5B is a schematic cross-sectional view showing a radial cross-section of a graphite substrate 2 having a polycrystalline SiC film 4 formed thereon, which is obtained by removing the polycrystalline SiC film 4 on the outer periphery of a circular plate and then equally cutting the thickness of the graphite substrate 2;

[0049] Figure 6It is a graph showing the respective peak intensity ratios (A / B) calculated from the X-ray diffraction patterns of the polycrystalline SiC compacts obtained in Example 1 and Example 7 according to the embodiments. Detailed implementation mode

[0050] The embodiments of the present invention will be described in detail below with reference to the drawings. The following detailed description of the present invention is one example of the embodiments, and the present invention is not limited or interpreted by this embodiment in any way.

[0051] Figure 1 It is a schematic cross-sectional view showing the laminated SiC substrate 30 of this embodiment. As Figure 1 shown, the laminated SiC substrate 30 has a polycrystalline SiC compact 10 and a single-crystalline SiC layer 21.

[0052] The polycrystalline SiC compact 10 is provided to support the single-crystalline SiC layer 21. The polycrystalline SiC compact 10 is plate-shaped and has a thickness that is easy to handle, for example, a thickness of about 300 to 500 μm.

[0053] The above-mentioned laminated SiC substrate 30 can be manufactured, for example, through the following steps.

[0054] First, as Figure 2A shown, a polycrystalline SiC compact 10 and a single-crystalline SiC substrate 20 having a certain thickness are prepared respectively. The surfaces for bonding the polycrystalline SiC compact 10 and the single-crystalline SiC substrate 20 are respectively referred to as the bonding surface of the polycrystalline SiC compact 10 and the bonding surface of the single-crystalline SiC substrate 20. Hydrogen ions are implanted from the direction opposite to the bonding surface of the single-crystalline SiC substrate 20 into the region at a fixed depth from the bonding surface of the single-crystalline SiC substrate 20, so that a fragile layer t is formed in the region at a fixed depth from the bonding surface of the single-crystalline SiC substrate 20. Here, the fragile layer t is the layer buried in the region at a fixed depth from the bonding surface of the single-crystalline SiC substrate 20, which is indicated by a dotted line in Figure 2A and Figure 2B Then, an argon beam is irradiated onto the bonding surface of the single-crystalline SiC substrate 20 and the bonding surface of the polycrystalline SiC compact 10 to activate their surfaces together. After that, the bonding surface of the single-crystalline SiC substrate 20 and the bonding surface of the polycrystalline SiC compact 10 are arranged in a form where the bonding surfaces are opposite to each other, and their bonding surfaces are bonded to each other. Then, for the single-crystalline SiC substrate 20 and the polycrystalline SiC compact 10 bonded through their bonding surfaces, as Figure 2BAs shown, the single-crystal SiC substrate 20 and the polycrystalline SiC compact 10 are separated with the fragile layer t as the boundary. At this time, on the bonding surface of the polycrystalline SiC compact 10, a part of the single-crystal SiC substrate 20 separated with the fragile layer t as the boundary (hereinafter referred to as the single-crystal SiC layer 21) is fixedly provided. Thus, the Figure 1 laminated SiC substrate 30 shown is obtained.

[0055] The single-crystal SiC layer 21 is the part for forming a semiconductor circuit. On the single-crystal SiC layer 21, a single-crystal layer for forming a semiconductor circuit is formed by epitaxial growth, and a semiconductor circuit is formed through a prescribed processing step. The thickness of the single-crystal SiC layer 21 only needs to be a thickness such that a single-crystal layer can be grown thereon by epitaxial growth, and is sufficiently small compared to the thickness of the polycrystalline SiC compact 10. For example, the thickness of the single-crystal SiC layer 21 is about 0.5 μm.

[0056] According to the above laminated SiC substrate 30, since the polycrystalline SiC compact 10 functions as a support substrate, the thickness of the single-crystal SiC layer 21 can be made smaller than that of the single-crystal SiC substrate 20. Generally, single-crystal SiC materials are more expensive than polycrystalline SiC materials. By reducing the thickness of the single-crystal SiC layer 21, the material cost can be reduced, and thus the laminated SiC substrate 30 for manufacturing a semiconductor device can be manufactured at a low cost.

[0057] On the other hand, for the polycrystalline SiC compact 10 used for the above laminated SiC substrate 30, since it is to be bonded to the single-crystal SiC substrate 20, it needs to have a flat surface. If the bonding surface of the polycrystalline SiC compact 10 is not flat, it is difficult to properly bond the polycrystalline SiC compact 10 and the single-crystal SiC substrate 20.

[0058] In addition, depending on the use of the laminated SiC substrate 30, in operation, sometimes current may flow across the bonding surface of the polycrystalline SiC compact 10 and the fragile layer t. In this case, it is necessary to reduce the contact resistance of the bonding surface between the polycrystalline SiC compact 10 and the single-crystal SiC layer 21. In order to reduce the contact resistance, the polycrystalline SiC compact 10 needs to be of low resistance.

[0059] In order to meet the above requirements, in the present embodiment, through efforts, the polycrystalline SiC compact 10 has a flat bonding surface and is of low resistance. The polycrystalline SiC compact 10 will be described in detail below.

[0060] The polycrystalline SiC compact 10 has a resistivity of 0.050 Ωcm or less. With such a resistivity, the barrier at the bonding interface between the polycrystalline SiC compact 10 and the single-crystalline SiC layer 21 can be suppressed, thereby improving the responsiveness of the device. In addition, from the perspective of ensuring stable device responsiveness, the resistivity of the polycrystalline SiC compact 10 is preferably 0.030 Ωcm or less, and more preferably 0.020 Ωcm or less.

[0061] The resistivity can be adjusted, for example, by incorporating a specified amount of nitrogen into the polycrystalline SiC compact 10. The resistivity can be reduced by increasing the nitrogen content.

[0062] The nitrogen content of the polycrystalline SiC compact 10 is, for example, 200 ppm (parts per million by mass) or more, and preferably 200 to 1000 ppm (parts per million by mass). When the nitrogen content is within this range, the degree of change in resistivity with respect to changes in nitrogen content becomes smaller. Therefore, by controlling the nitrogen content, the desired resistivity can be easily obtained. In addition, if the nitrogen content is 1000 ppm (parts per million by mass) or less, the crystal defects generated due to the introduction of nitrogen hardly affect the flatness of the substrate.

[0063] It should be noted that the method of introducing nitrogen is not particularly limited. For example, as described later, when forming a polycrystalline SiC film by CVD, a nitrogen-containing gas can be used to introduce nitrogen into the formed polycrystalline SiC film.

[0064] The polycrystalline SiC compact 10 has a specified crystal structure. Specifically, in the X-ray diffraction pattern obtained from the polycrystalline SiC compact 10, the ratio (A / B) of the peak intensity “A” to the peak intensity “B” is 0.018 or less.

[0065] Here, the peak intensity “A” refers to the intensity (maximum value) of the diffraction peak in the range of diffraction angle 2θ of 33° to 34°. This peak is a known peak indicating the stacking defects of polycrystalline SiC materials.

[0066] In addition, the peak intensity “B” refers to the intensity of the diffraction peak of the SiC (111) plane. This peak generally appears in the range of diffraction angle 2θ of 35° to 36°.

[0067] The peak intensity ratio (A / B) being 0.018 or less means that the stacking defect concentration in the polycrystalline SiC material is sufficiently small. Stacking defects are one of the causes of substrate warping. The peak intensity ratio (A / B) being 0.018 or less can reduce the warping of the polycrystalline SiC compact 10, thereby providing a polycrystalline SiC compact 10 with a flat bonding surface.

[0068] It should be noted that, regarding the polycrystalline SiC compact 10, from the perspective of stably ensuring a flat joint surface, the peak intensity ratio (A / B) is more preferably 0.010 or less.

[0069] Next, a manufacturing method of the polycrystalline SiC compact 10 will be described. The polycrystalline SiC compact 10 having the above characteristics can be manufactured by a specific manufacturing method using the CVD method described below.

[0070] Figure 3 FIG. 1 is a schematic diagram showing an example of a manufacturing system used in the manufacturing method of the polycrystalline SiC compact 10 of the present embodiment. In this manufacturing system, a CVD furnace 1 and a mixer 3 are provided. A carrier gas, a source gas as a SiC supply source, and a nitrogen-containing gas are mixed in the mixer 3 to generate a mixed gas. The mixed gas is supplied from the mixer 3 to the CVD furnace 1. A plurality of graphite substrates 2 are provided in the CVD furnace 1. Each of the graphite substrates 2 has a disk shape. When the mixed gas is supplied to the CVD furnace 1, a polycrystalline SiC film is formed on each of the graphite substrates 2 by the CVD method. In addition, nitrogen from the nitrogen-containing gas is doped into the polycrystalline SiC film. The polycrystalline SiC film is separated from the graphite substrate 2 and processed into the polycrystalline SiC compact 10 by surface grinding.

[0071] It should be noted that as the source gas as a SiC supply source, either a single-component gas (a gas containing Si and C) or a two-component gas (a gas containing Si and a gas containing C) can be used.

[0072] Here, in the present embodiment, in order to obtain a polycrystalline SiC compact 10 having a flat surface, the source gas concentration during film formation by the CVD method was studied. It should be noted that in the present invention, the source gas concentration refers to the volume ratio (vol%) of the source gas with respect to the total amount of the source gas and the carrier gas.

[0073] Figure 4 FIG. 2 is a graph conceptually showing the relationship between the time during film formation and the source gas concentration. As Figure 4 shown, the manufacturing method of the present embodiment includes an initial process, a middle process, and a final process. The initial process, the middle process, and the final process are continuously implemented.

[0074] First, in the initial process, a first polycrystalline SiC film is formed on the graphite substrate 2 at a source gas concentration of a first concentration C1.

[0075] Next, in the middle process, the source gas concentration is reduced from the first concentration C1 to a second concentration C2, and a third polycrystalline SiC film is formed on the first polycrystalline SiC film. The source gas concentration is preferably reduced at a constant rate.

[0076] Then, in the final process, a second polycrystalline SiC film is formed at a raw material gas concentration of the second concentration C2.

[0077] According to the inventor's opinion, when forming a polycrystalline SiC film by CVD method with a constant raw material gas concentration, the crystal grain size is small in the initial stage of film formation, and as it enters the later stage of film formation, the crystal grain size tends to increase. In contrast, as in this embodiment, by increasing the raw material gas concentration in the initial process and decreasing the raw material gas concentration in the later process, throughout the entire film formation period, it is easy to make the crystal grain sizes of the entire polycrystalline SiC film including the first polycrystalline SiC film, the second polycrystalline SiC film, and the third polycrystalline SiC film consistent. By making the crystal grain sizes consistent, the density of stacking defects can be reduced, and a polycrystalline SiC film with less warpage can be obtained.

[0078] The time period (time period t1) of the initial process is not particularly limited. For example, it is 10% - 50% of the entire time period (T) of the polycrystalline SiC film formation period.

[0079] The time period (time period t2) of the middle process is also not particularly limited. For example, it is 10% - 50% of the entire time period (T) of the polycrystalline SiC film formation period.

[0080] The time period (time period t3) of the final process is also not particularly limited. For example, it is 30% - 70% of the entire time period (T) of the polycrystalline SiC film formation period.

[0081] The entire time period (T) of the polycrystalline SiC film formation period is not particularly limited. For example, it is 1 - 20 hours, preferably 5 - 15 hours.

[0082] The film thickness of the formed polycrystalline SiC film is, for example, 500 - 6000 μm, preferably 450 - 5500 μm.

[0083] The carrier gas used during film formation is not particularly limited. For example, hydrogen gas etc. can be used.

[0084] As the raw material gas, as long as it is a gas containing a supply source of Si and C, there is no particular limitation. For example, a gas containing Si and C in the molecule, or a mixed gas of a gas containing Si in the molecule and a hydrocarbon gas etc. can be used.

[0085] As the raw material gas, for example, in the case of a single - component gas, examples include: trichloromethylsilane, trichlorophenylsilane, dichloromethylsilane, dichlorodimethylsilane, trimethylchlorosilane, etc.; in the case of a two - component gas, examples include: trichlorosilane, and a mixture of a silane gas such as silane and a hydrocarbon gas, etc.

[0086] There are no particular restrictions on the specific film formation conditions using the CVD method. For example, the following conditions can be adopted.

[0087] The raw material gas concentration (first concentration C1) in the initial process only needs to be greater than the raw material gas concentration (second concentration C2) in the final process. From the perspective of suppressing warping of the polycrystalline SiC compact, in order to unify the SiC crystal grain size throughout the film formation period, the first concentration is preferably 1.2 to 2.0 times the second concentration; in order to stably obtain a unified SiC crystal grain size, the first concentration is more preferably 1.3 to 1.8 times the second concentration; in order to stably and efficiently obtain a unified SiC crystal grain size, the first concentration is further preferably 1.4 to 1.6 times the second concentration.

[0088] The second concentration C2 is, for example, 3 to 40 vol%, preferably 5 to 20 vol%.

[0089] The gas residence time in the CVD furnace is, for example, 10 to 200 seconds, preferably 20 to 100 seconds.

[0090] The reaction temperature is, for example, 1100 to 1900 °C, preferably 1400 to 1600 °C.

[0091] The flow rate of the nitrogen-containing gas relative to the total flow rate of the raw material gas flow rate and the carrier gas flow rate is, for example, 5 to 100 vol%, preferably 10 to 70 vol%.

[0092] For example, when the raw material gas is a gaseous raw material, the raw material gas concentration can be adjusted by controlling the raw material gas flow rate and the carrier gas flow rate. In addition, when the raw material gas is a gas from a liquid raw material, the raw material gas concentration can be adjusted by controlling the temperature of the liquid raw material in the raw material tank and controlling the vapor pressure of the liquid raw material.

[0093] After the film formation process of the polycrystalline SiC film using the CVD method is completed, each graphite substrate 2 on which the polycrystalline SiC film 4 is formed is taken out from the CVD furnace 1, and then processed as needed to take out only the polycrystalline SiC compact 10.

[0094] Figure 5A is a schematic cross-sectional view of the radial direction of the graphite substrate 2 having the center line O-O' on which the polycrystalline SiC film 4 is formed. Here, the polycrystalline SiC film 4 is formed on the entire surface of the graphite substrate 2. For example, first, the outer periphery of the graphite substrate 2 on which the polycrystalline SiC film 4 is formed is processed. Specifically: along Figure 5A the indicated breaking line A-A', only the outer peripheral portion of the graphite substrate 2 on which the polycrystalline SiC film 4 is formed is cut and removed. Then, as Figure 5AAs shown, along the line that bisects the thickness of the graphite substrate 2, i.e., the breaking line B - B', the graphite substrate 2 on which the polycrystalline SiC film 4 is formed is cut to divide it into two in the thickness direction. As a result, as Figure 5B shown, a laminate of the graphite substrate 2 and the polycrystalline SiC film 4 is obtained. Next, using oxidation or shot peening method, etc., only the graphite substrate 2 is removed from this laminate. After that, by grinding process, etc., the exposed surface of the polycrystalline SiC film 4 exposed by removing the graphite substrate 2 is ground. Through the processing methods exemplified above, a polycrystalline SiC compact 10 can be obtained.

[0095] As described above, according to the present embodiment, when forming the polycrystalline SiC film by CVD method, since a high raw material gas concentration is used in the initial process and a low raw material gas concentration is used in the final process, the crystal grain size can be made uniform. As a result, stacking defects can be reduced, and a polycrystalline SiC compact 10 having a flat surface can be realized.

[0096] In addition, since the nitrogen content is controlled to a specified value, a polycrystalline SiC compact 10 with low resistance can be obtained.

[0097] It should be noted that in the present embodiment, the case where the polycrystalline SiC compact 10 is joined to the single crystal SiC layer 21 and used as the stacked SiC substrate 30 has been described. According to the present embodiment, since the obtained polycrystalline SiC compact 10 has low resistance and a flat surface, it is suitable for such uses. However, the polycrystalline SiC compact 10 of the present embodiment is not limited to being joined and used with the single crystal SiC substrate 20, and can also be appropriately applied to other uses as long as high flatness and low resistivity are required.

[0098] Moreover, as described in the above embodiment, the polycrystalline SiC compact of the present invention can be appropriately used in the case of being joined to the single crystal SiC layer, and in addition to the cases shown in the above embodiment, it can also be similarly applied to other known joining methods such as SIMOX (Separation by Implanted Oxygen) method and ELTRAN method.

[0099] For example, the polycrystalline SiC compact of the present embodiment is used as components for plasma etching devices such as edge rings, electrode plates, and heaters when manufacturing semiconductors. In addition, it is used as components for semiconductor heat treatment devices such as dummy wafers when manufacturing semiconductors.

[0100] It should be noted that when used as an edge ring and an electrode plate, the polycrystalline SiC substrate has a thickness of about 2000 - 5000 μm, for example. In addition, when used as a dummy wafer, the polycrystalline SiC substrate has a thickness of about 300 - 1000 μm, for example.

[0101] Examples

[0102] For a more detailed description of the present invention, the following describes the embodiments carried out by the present inventor. However, the present invention should not be construed as being limited by the following embodiments.

[0103] (Example 1)

[0104] In a CVD furnace, a graphite substrate with a diameter of 160 mm and a thickness of 5 mm was set. Trimethylchlorosilane (source gas), hydrogen (carrier gas), and nitrogen were introduced into the CVD furnace and processed at 1500 °C for 10 hours, and a polycrystalline SiC film was formed on the graphite substrate.

[0105] The film formation conditions are shown in Table 1.

[0106] It should be noted that the concentration of the source gas was changed between the initial stage of film formation (from the start of film formation to 2.5 hours), the middle stage of film formation (2.5 hours to 5 hours after the start of film formation), and the later stage of film formation (5 hours to 10 hours after the start of film formation). Specifically, the concentration of the source gas in the initial stage of film formation (the first concentration) was set to 9.0 vol%, and the concentration of the source gas in the later stage of film formation (the second concentration) was set to 7.5 vol%.

[0107] That is, the ratio of the concentration of the source gas in the initial stage of film formation to the concentration of the source gas in the later stage of film formation (referred to as the source gas concentration ratio) was set to 1.2 times. In addition, in the middle stage of film formation, the concentration of the source gas was decreased at a fixed rate from the concentration in the initial stage of film formation to the concentration in the later stage of film formation. It should be noted that the total value of the source gas flow rate and the carrier gas flow rate was controlled at a fixed value (140 L / min).

[0108] In addition, the nitrogen flow rate was constant throughout the film formation period. Specifically, the nitrogen flow rate was set to 17.5 (L / min).

[0109] The gas residence time was 44.1 (seconds). It should be noted that the gas residence time was calculated by the following formula.

[0110] (Equation 1): Gas residence time (seconds) = (furnace volume / gas flow rate) × ((20 + 273) / (reaction temperature + 273)) × 60

[0111] After film formation, the graphite substrate was taken out of the CVD furnace, and peripheral processing and cutting processing were performed. Then, the graphite substrate was removed, and a polycrystalline SiC compact with a diameter of 150 mm and a thickness of 0.6 mm was obtained. Through surface grinding, a polycrystalline SiC compact with a diameter of 150 mm and a thickness of 0.4 mm was obtained. This was obtained as the polycrystalline SiC compact of Example 1.

[0112] (Examples 2 to 7)

[0113] Using the same method as in Example 1, polycrystalline SiC compacts of Examples 2 to 7 were obtained. However, the film formation conditions were changed as shown in Table 1.

[0114] (Example 8)

[0115] Using the same method as in Example 1, a polycrystalline SiC compact of Example 8 was obtained. However, from the start to the end of film formation, the raw material gas concentration was fixed at 7.5 vol%. In addition, the nitrogen gas flow rate was changed to the value described in Table 1.

[0116] (Measurement of resistivity)

[0117] Using the four-point probe method, the resistivity of the polycrystalline SiC compacts obtained in Examples 1 to 8 was measured. For the resistivity measurement, Loresta-GP MCT-T610 manufactured by Mitsubishi Chemical Analytech Co., Ltd. was used.

[0118] (Measurement of peak intensity ratio)

[0119] Using XRD-6000 manufactured by Shimadzu Corporation, the X-ray diffraction pattern by the 2θ / θ method of the obtained polycrystalline SiC compact was measured under the following conditions.

[0120] Cu target

[0121] Voltage: 40.0 kV

[0122] Current: 20.0 mA

[0123] Divergence slit: 1.00000 degree (deg)

[0124] Scattering slit: 1.00000 degree

[0125] Receiving slit: 0.30000 mm

[0126] Scanning range: 32.000 to 36.000 degrees

[0127] Scanning speed: 0.1000 degree / min

[0128] Sampling interval: 0.0100 degree

[0129] Preset time: 6.00 sec

[0130] In the obtained X-ray diffraction pattern, the average value of the diffraction peak intensities in the range of diffraction angle 2θ of 32.2° to 33.2° was used as the background correction value. Peak "A" and peak "B" were obtained by subtracting the respective background correction values from the diffraction peak intensity in the range of diffraction angle 2θ of 33° to 34° being set as the peak intensity "A" (before correction) and the diffraction peak intensity in the range of diffraction angle 2θ of 35° to 36° being set as the peak intensity "B" (before correction), and the peak intensity ratio (A / B) was calculated.

[0131] (Measurement of warpage amount)

[0132] In addition, the warpage amount of the obtained polycrystalline SiC compact was measured using an optical interference type warpage amount measuring device (FlatMaster200XRA-Indurstrial manufactured by CORNING TROPEL).

[0133] (Measurement of nitrogen content)

[0134] The nitrogen content in the polycrystalline SiC compact was measured using SIMS-4000 manufactured by ATOMIKA.

[0135] (Results of investigation)

[0136] The measurement results of resistivity, peak intensity ratio, warpage amount, and nitrogen content are shown in Table 1.

[0137] Compared with Examples 7 to 8, the peak intensity ratios of Examples 1 to 6 were small (0.018 or less), and the warpage amounts were also small. That is, it can be understood that by changing the raw material gas concentration with a specific behavior during film formation, stacking defects can be reduced, and ultimately the warpage amount can be reduced.

[0138] In addition, in Examples 1 to 6, the nitrogen content was all 1000 ppm (parts per million by mass) or less, and the resistance values were all 0.050 Ω·cm or less. It is generally considered that as the nitrogen content increases, crystal defects increase, leading to warpage. However, from the results of Examples 1 to 6, it can be seen that if the nitrogen content is 1000 ppm (parts per million by mass) or less, warpage can also be sufficiently suppressed.

[0139] [Table 1]

[0140]

[0141] Symbol description

[0142] 1 CVD furnace

[0143] 2 Graphite substrate

[0144] 3 Mixer

[0145] 4 Polycrystalline SiC film

[0146] 10 Polycrystalline SiC formed body

[0147] 20 Single crystal SiC substrate

[0148] 21 Single crystal SiC layer

[0149] 30 Stacked SiC substrate.

Claims

1. A polycrystalline SiC compact, wherein, The resistivity of the polycrystalline SiC compact measured by the four-point probe method is 0.050 Ωcm or less. In the X-ray diffraction pattern, the diffraction peak intensity of the stacking defects of polycrystalline SiC in the range of diffraction angle 2θ of 33° to 34° is "A", and in the X-ray diffraction pattern, the diffraction peak intensity of the SiC (111) plane in the range of diffraction angle 2θ of 35° to 36° is "B", and the ratio A / B is 0.018 or less. Among them, the ratio A / B is calculated as follows: In the obtained X-ray diffraction pattern, the average value of the diffraction peak intensities in the range of diffraction angle 2θ of 32.2° to 33.2° is used as the background correction value. By setting the diffraction peak intensity in the range of diffraction angle 2θ of 33° to 34° as the peak intensity "A" before correction, and the diffraction peak intensity in the range of diffraction angle 2θ of 35° to 36° as the peak intensity "B" before correction, subtracting the respective background correction values, the peak "A" and peak "B" are obtained, and the peak intensity ratio A / B is calculated. Among them, the polycrystalline SiC compact is obtained by separating and processing a polycrystalline SiC film from a graphite substrate, and the polycrystalline SiC compact has a thickness of 300 μm to 1000 μm and a nitrogen content of 200 ppm to 1000 ppm by mass parts per million.

2. A method for manufacturing the polycrystalline SiC compact according to claim 1, wherein the polycrystalline SiC compact is manufactured by a CVD method, and the method includes: In the initial process, a first polycrystalline SiC film is formed on the substrate at the raw material gas concentration of the first concentration; In the middle process, the raw material gas concentration is decreased from the first concentration to the second concentration at a fixed speed to form a third polycrystalline SiC film; In the final process, a second polycrystalline SiC film is formed at the raw material gas concentration of the second concentration lower than the first concentration; Among them, the polycrystalline SiC compact has a thickness of 300 μm to 1000 μm, the polycrystalline SiC compact has a nitrogen content of 200 ppm to 1000 ppm by mass parts per million.

3. The method according to claim 2, wherein, The first concentration is 1.2 to 2.0 times the second concentration.

4. The method according to claim 2, wherein, The time period of the initial process is 10% to 50% of the total time period of the film formation period of the polycrystalline SiC film.

5. The method according to claim 3, wherein, The time period of the initial process is 10% to 50% of the total time period of the film formation period of the polycrystalline SiC film.

6. The method according to any one of claims 2 to 5, wherein, The time period of the middle process is 10% to 50% of the total time period of the film formation period of the polycrystalline SiC film, and the time period of the final process is not 0%.

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