A polycrystalline SiC compact

Abstract

The present invention provides a polycrystalline SiC compact having a resistivity of 0.050 Ωcm or less. When the peak intensity in the wavenumber range of 760 to 780 cm-1 in the Raman spectrum is “A” and the peak intensity in the wavenumber range of 790 to 800 cm-1 in the Raman spectrum is “B”, the peak ratio (A / B) is 0.100 or less.

Description

Technical Field

[0001] The present invention relates to a polycrystalline SiC compact. Background Art

[0002] SiC compacts are excellent in various properties such as heat resistance, corrosion resistance, and strength, and are used for various purposes. 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 semiconductor manufacturing. 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 specified 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 use.

[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, if it is to be used for a purpose such as forming a current path across the joining surface of the polycrystalline SiC compact and the 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 low resistance and excellent flatness.

[0013] Means for Solving the Problems

[0014] In order to solve the above problems, the present invention includes the following.

[0015] [1] A polycrystalline SiC compact, wherein the resistivity of the polycrystalline SiC compact is 0.050 Ωcm or less, and the peak intensity in the range of 760 to 780 cm -1 in the Raman spectrum is "A", and the peak intensity in the range of 790 to 800 cm -1 in the Raman spectrum is "B", then the peak ratio (A / B) is 0.100 or less.

[0016] [2] The polycrystalline SiC compact according to [1], wherein the nitrogen content is 200 ppm (parts per million by mass) or more.

[0017] Advantages of the Invention

[0018] The present invention can provide a polycrystalline SiC compact having excellent flatness and low resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic cross-sectional view showing a laminated SiC substrate of an embodiment;

[0020] Figure 2A is a schematic cross-sectional view showing a method of manufacturing a laminated SiC substrate;

[0021] Figure 2B is a schematic cross-sectional view showing a method of manufacturing a laminated SiC substrate;

[0022] Figure 3 is a schematic view showing an example of a manufacturing system used in a method of manufacturing a polycrystalline SiC substrate;

[0023] Figure 4 is a graph conceptually showing the relationship between the time during film formation and the concentration of the source gas;

[0024] 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;

[0025] 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, in which the polycrystalline SiC film 4 on the outer periphery of the disk is removed and the thickness of the graphite substrate 2 is evenly cut;

[0026] Figure 6 is a graph showing the respective peak ratios (A / B) calculated from the Raman spectra of the polycrystalline SiC compacts obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0027] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following detailed description of the present invention is one example of the embodiments, and the present invention is not limited or construed by any of these embodiments.

[0028] Figure 1 is a schematic cross-sectional view showing the laminated SiC substrate 30 of the present embodiment. As Figure 1 shown, the laminated SiC substrate 30 has a polycrystalline SiC compact 10 and a single-crystalline SiC layer 21.

[0029] 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.

[0030] The above-mentioned laminated SiC substrate 30 can be manufactured, for example, by the following steps.

[0031] 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 a 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 a layer Figure 2A and Figure 2B shown by a dotted line and buried in the region at a fixed depth from the bonding surface of the single-crystalline SiC substrate 20. 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 manner that the activated bonding surfaces of the single-crystalline SiC substrate 20 and the polycrystalline SiC compact 10 face 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 2B shown, with the fragile layer t as the boundary, the single-crystalline SiC substrate 20 and the polycrystalline SiC compact 10 are separated. At this time, on the bonding surface of the polycrystalline SiC compact 10, a part of the single-crystalline SiC substrate 20 separated with the fragile layer t as the boundary (hereinafter referred to as the single-crystalline SiC layer 21) is fixedly provided. Thus, the Figure 1 shown laminated SiC substrate 30 is obtained.

[0032] The single-crystalline SiC layer 21 is a part for forming a semiconductor circuit. On the single-crystalline SiC layer 21, a single-crystalline 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-crystalline SiC layer 21 only needs to be a thickness such that a single-crystalline 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-crystalline SiC layer 21 is about 0.5 μm.

[0033] According to the above-described laminated SiC substrate 30, since the polycrystalline SiC compact 10 functions as a support substrate, the thickness of the single-crystalline SiC layer 21 can be made smaller than that of the single-crystalline SiC substrate 20. Generally, single-crystalline SiC materials are more expensive than polycrystalline SiC materials. By reducing the thickness of the single-crystalline 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.

[0034] On the other hand, for the polycrystalline SiC compact 10 used for the above-described laminated SiC substrate 30, since it is to be joined to the single-crystalline SiC substrate 20, it needs to have a flat surface. If the joining surface of the polycrystalline SiC compact 10 is not flat, it is difficult to properly join the polycrystalline SiC compact 10 and the single-crystalline SiC substrate 20.

[0035] In addition, depending on the use of the laminated SiC substrate 30, during operation, sometimes current flows across the joining 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 joining surface between the polycrystalline SiC compact 10 and the single-crystalline SiC layer 21. In order to reduce the contact resistance, the polycrystalline SiC compact 10 must have a low resistance.

[0036] In order to meet the above requirements, in the present embodiment, through efforts, the polycrystalline SiC compact 10 has a flat joining surface and has a low resistance. The polycrystalline SiC compact 10 will be described in detail below.

[0037] The polycrystalline SiC compact 10 has a resistivity of 0.050 Ω·cm or less. With this resistivity, the barrier at the joining surface between the polycrystalline SiC compact 10 and the single-crystalline SiC layer 21 is suppressed, and thus the responsiveness of the device can be improved. In addition, from the viewpoint of ensuring stable device responsiveness, the resistivity of the polycrystalline SiC compact 10 is preferably 0.030 Ω·cm or less, and more preferably 0.020 Ω·cm or less.

[0038] The resistivity can be adjusted, for example, by making the polycrystalline SiC compact 10 contain a prescribed amount of nitrogen. The resistivity can be reduced by increasing the nitrogen content.

[0039] The nitrogen content of the polycrystalline SiC compact 10 is, for example, 200 ppm (parts per million by mass) or more, 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 the change 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 by the introduction of nitrogen hardly affect the flatness of the substrate.

[0040] 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 method, a nitrogen-containing gas can be used to introduce nitrogen into the formed polycrystalline SiC film.

[0041] The surface structure of the polycrystalline SiC compact 10 has a specified crystal structure.

[0042] Specifically, regarding this surface structure, in the Raman spectrum, the intensity (maximum value) of the peak in the wavenumber range of 760 to 780 cm -1 (hereinafter referred to as peak A) is "A", and in the Raman spectrum, the intensity (maximum value) of the peak in the wavenumber range of 790 to 800 cm -1 (hereinafter referred to as peak B) is "B", then the Raman peak ratio (A / B) is 0.100 or less.

[0043] Here, peak A is a peak indicating the stacking defects of the polycrystalline SiC material.

[0044] On the other hand, peak B is a peak indicating β-SiC.

[0045] The Raman peak ratio (A / B) being 0.100 or less means that in the surface structure of the polycrystalline SiC compact 10, the density of stacking defects is sufficiently small. Stacking defects are one of the causes of substrate warping. The Raman peak ratio (A / B) being 0.100 or less can reduce the warping of the polycrystalline SiC compact 10, thereby providing a polycrystalline SiC compact 10 having a flat surface structure (bonding surface).

[0046] Next, the 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.

[0047] Figure 3FIG. 0 is a schematic diagram showing an example of a manufacturing system used in the method for manufacturing the polycrystalline SiC compact 10 of the present embodiment. In this manufacturing system, a CVD furnace 1 and a mixer 3 are provided. In the mixer 3, a carrier gas, a source gas as a SiC source, and a nitrogen-containing gas are mixed 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 disc 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 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.

[0048] It should be noted that as the source gas for SiC, 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.

[0049] Here, in the present embodiment, in order to obtain a polycrystalline SiC compact 10 having a flat surface, the concentration of the source gas during film formation by 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.

[0050] Figure 4 FIG. 10 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 carried out.

[0051] First, in the initial process, a first polycrystalline SiC film is formed on the graphite substrate 2 at a source gas concentration of the first concentration C1.

[0052] Next, in the middle process, the source gas concentration is reduced from the first concentration C1 to the second concentration C2, and a second polycrystalline SiC film is formed on the first polycrystalline SiC film. The source gas concentration is preferably reduced at a constant rate.

[0053] Then, in the final process, a third polycrystalline SiC film is formed at a source gas concentration of the second concentration C2.

[0054] According to the inventor's opinion, when the concentration of the source gas is set constant and a polycrystalline SiC film is formed by CVD method, 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 concentration of the source gas in the initial process and decreasing the concentration of the source gas in the later process, 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 throughout the film formation period. 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.

[0055] The time period of the initial process (time period t1) is not particularly limited. For example, it is 10% to 50% of the entire time period (T) of the film formation period of the polycrystalline SiC film.

[0056] The time period of the middle process (time period t2) is also not particularly limited. For example, it is 10% to 50% of the entire time period (T) of the film formation period of the polycrystalline SiC film.

[0057] The time period of the final process (time period t3) is also not particularly limited. For example, it is 30% to 70% of the entire time period (T) of the film formation period of the polycrystalline SiC film.

[0058] The entire time period (T) of the film formation period of the polycrystalline SiC film is not particularly limited. For example, it is 1 to 20 hours, preferably 5 to 15 hours.

[0059] The film thickness of the formed polycrystalline SiC film is, for example, 500 to 6000 μm, preferably 450 to 5500 μm.

[0060] The carrier gas used during film formation is not particularly limited. For example, hydrogen gas can be used.

[0061] As the source 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 can be used.

[0062] As the source 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.

[0063] The specific film formation conditions using CVD are not particularly limited. For example, the following conditions can be adopted.

[0064] The raw material gas concentration (the first concentration C1) in the initial process only needs to be greater than the raw material gas concentration (the second concentration C2) in the final process. From the perspective of suppressing the 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.

[0065] The second concentration C2 is, for example, 3 to 40 vol%, preferably 5 to 20 vol%.

[0066] The gas residence time in the CVD furnace is, for example, 10 to 200 seconds, preferably 20 to 100 seconds.

[0067] The reaction temperature is, for example, 1100 to 1900 °C, preferably 1400 to 1600 °C.

[0068] The flow rate of the nitrogen-containing gas is, for example, 5 to 100 vol% relative to the total flow rate of the raw material gas flow rate and the carrier gas flow rate, preferably 10 to 70 vol%.

[0069] 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.

[0070] 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.

[0071] Figure 5A It 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 shown break 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 5A shown, along the line that bisects the thickness of the graphite substrate 2, that is, the break 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 5BAs shown, a laminate of a graphite substrate 2 and a polycrystalline SiC film 4 is obtained. Next, only the graphite substrate 2 is removed from this laminate by using oxidation or shot peening method or the like. After that, the exposed surface of the polycrystalline SiC film 4 exposed by removing the graphite substrate 2 is ground by grinding or the like. By the processing methods exemplified above, a polycrystalline SiC compact 10 can be obtained.

[0072] As described above, in this embodiment, a polycrystalline SiC film having a surface structure with a Raman peak ratio (A / B) of 0.100 or less can be obtained, and thus a polycrystalline SiC substrate 10 having a flat surface can be realized.

[0073] In addition, since the nitrogen content is controlled to a specified value, a polycrystalline SiC compact 10 with low resistance can be obtained.

[0074] It should be noted that in this embodiment, the case where the polycrystalline SiC compact 10 is joined to a single-crystalline SiC layer 21 and used as a laminated SiC substrate 30 has been described. According to this embodiment, since a polycrystalline SiC compact 10 having low resistance and a flat surface is obtained, it is suitable for such a use. However, the polycrystalline SiC compact 10 of this embodiment is not limited to being joined and used with a single-crystalline SiC substrate 20, and can also be appropriately applied to other uses as long as high flatness and low resistivity are required.

[0075] Moreover, as described in the above embodiment, the polycrystalline SiC compact of the present invention can be appropriately used in the case of joining to a single-crystalline SiC layer, and in addition to the case 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.

[0076] For example, the polycrystalline SiC compact of this embodiment is used as a component for a plasma etching device, such as an edge ring, an electrode plate, and a heater, when manufacturing a semiconductor. In addition, it is used as a component for a semiconductor heat treatment device, such as a dummy wafer, when manufacturing a semiconductor.

[0077] 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.

[0078] [Examples]

[0079] To explain the present invention in more detail, examples conducted by the present inventors will be described below. However, the present invention should not be construed as being limited by the following examples.

[0080] (Example 1)

[0081] In the CVD furnace, a graphite substrate with a diameter of 160 mm and a thickness of 5 mm was set. Trimethylchlorosilane (raw material gas), hydrogen (carrier gas), and nitrogen were introduced into the CVD furnace and treated at 1500 °C for 10 hours, and a polycrystalline SiC film was formed on the graphite substrate.

[0082] The film formation conditions are shown in Table 1.

[0083] It should be noted that the concentration of the raw material 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 final stage of film formation (5 hours to 10 hours after the start of film formation). Specifically, the concentration of the raw material gas in the initial stage of film formation (the first concentration) was set to 9.0 vol%, and the concentration of the raw material gas in the final stage of film formation (the second concentration) was set to 7.5 vol%.

[0084] That is, the ratio of the concentration of the raw material gas in the initial stage of film formation to the concentration of the raw material gas in the final stage of film formation (referred to as the raw material gas concentration ratio) was set to 1.2 times. In addition, in the middle stage of film formation, the concentration of the raw material gas was decreased at a fixed rate from the concentration in the initial stage of film formation to the concentration in the final stage of film formation. It should be noted that the total value of the raw material gas flow rate and the carrier gas flow rate was controlled at a fixed value (140 L / min).

[0085] In addition, throughout the film formation period, the nitrogen flow rate was constant. Specifically, the nitrogen flow rate was set to 19.0 (L / min).

[0086] The gas residence time was 43.7 (seconds). It should be noted that the gas residence time was calculated by the following formula.

[0087] (Equation 1): Gas residence time (seconds) = (furnace volume / gas flow rate) × ((20 + 273) / (reaction temperature + 273)) × 60

[0088] After film formation, the graphite substrate was taken out of the CVD furnace and subjected to peripheral processing and cutting processing. 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.

[0089] (Examples 2 to 6, Comparative Examples 1 to 2)

[0090] Using the same method as in Example 1, polycrystalline SiC compacts of Examples 2 to 6 and Comparative Examples 1 to 2 were obtained. However, the film formation conditions were changed as shown in Table 1. It should be noted that in Comparative Example 1, the raw material gas flow rate was set to be constant (10.50 L / min).

[0091] (Measurement of Resistivity)

[0092] Using the four-point probe method, the resistivity of the polycrystalline SiC compacts obtained in each example and comparative example was measured. The resistivity was measured using a Loresta-GP MCT-T610 manufactured by Mitsubishi Chemical Analytech Co., Ltd.

[0093] (Measurement of Raman Spectrum)

[0094] Using a microscopic Raman spectrometer LabRAM HR800 manufactured by Horiba, Ltd., the Raman spectrum of the obtained polycrystalline SiC compacts was measured under the following conditions.

[0095] Excitation wavelength: 532 nm

[0096] Irradiation diameter:

[0097] Exposure time: 15 s

[0098] Accumulation times: 2

[0099] Grating: 1800 gr / mm

[0100] Set under the above conditions, the Raman spectrum of the obtained polycrystalline SiC compacts was processed as follows, and the peak ratio (A / B) was calculated. First, the arithmetic mean of the Raman scattering intensity in the range of wavenumbers from 850 to 900 cm -1 was used as the background correction value. Next, the peak intensity of the Raman spectrum at a wavenumber of 766 cm -1 and the peak intensity of the Raman spectrum at a wavenumber of 795 cm -1 were obtained, and the above background correction value was subtracted from each of these values to obtain the peak values after removing the background. At this time, the peak intensity at a wavenumber of 766 cm -1 was set as "A", and the peak intensity at a wavenumber of 795 cm -1 was set as "B". The peak ratio (A / B) was calculated based on these values.

[0101] (Measurement of Warpage)

[0102] In addition, using an optical interferometric warpage measurement device (FlatMaster 200XRA-Indurstrial manufactured by CORNING TROPEL), the warpage of the obtained polycrystalline SiC compacts was measured.

[0103] (Measurement of Nitrogen Content)

[0104] Using a SIMS-4000 manufactured by ATOMIKA, the nitrogen content in the polycrystalline SiC compacts was measured.

[0105] (Investigation results)

[0106] The measurement results of resistivity, peak ratio of Raman spectrum, warpage amount, and nitrogen content are shown in Table 1. In addition, the graph showing each peak ratio (A / B) calculated from the Raman spectra of the polycrystalline SiC compacts obtained in Example 1 and Comparative Example 1 is shown in Figure 6 .

[0107] The warpage amounts of Examples 1 to 6 were smaller than those of Comparative Examples 1 and 2. The peak ratios of the Raman spectra of Examples 1 to 6 were 0.100 or less. On the other hand, the peak ratios of Comparative Examples 1 and 2 exceeded 0.100. That is, it can be understood that a flat polycrystalline SiC substrate can be obtained when the peak ratio of the Raman spectrum is 0.100 or less.

[0108] In addition, in Examples 1 to 6, the nitrogen content was 200 to 1000 ppm (parts per million by mass), and the resistance value was 0.050 Ωcm or less. Generally, it is 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 be sufficiently suppressed.

[0109] [Table 1]

[0110]

[0111] Symbol Explanation

[0112] 1 CVD furnace

[0113] 2 Graphite substrate

[0114] 3 Mixer

[0115] 4 Polycrystalline SiC film

[0116] 10 Polycrystalline SiC compact

[0117] 20 Single-crystal SiC substrate

[0118] 21 Single-crystal SiC layer

[0119] 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 Raman spectrum with an excitation wavelength of 532 nm, the peak intensity in the wavenumber range of 760 - 780 cm -1 is "A", and in the Raman spectrum, the peak intensity in the wavenumber range of 790 - 800 cm -1 is "B", then the peak ratio A / B is 0.100 or less. Among them, the peak ratio A / B is calculated as follows: First, the arithmetic mean of the Raman scattering intensities in the wavenumber range of 850-900 cm -1 is used as the background correction value. Then, the peak intensity of the Raman spectrum at a wavenumber of 766 cm -1 and the peak intensity of the Raman spectrum at a wavenumber of 795 cm -1 are obtained. The above background correction value is subtracted from these values respectively as the values of the peaks after removing the background. At this time, the peak intensity at a wavenumber of 766 cm -1 is set as "A", and the peak intensity at a wavenumber of 795 cm -1 is set as "B", and the peak ratio A / B is calculated from these values. wherein 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.

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