Polycrystalline SiC molded body and method for producing same
By controlling the difference in the area fraction of the region of the specific crystal plane orientation in the polycrystalline SiC molded body, the problem of insufficient flatness of the polycrystalline SiC molded body is solved, and the effect of high flatness and warpage is achieved. It is suitable for applications such as plasma etching devices.
Patent Information
- Application Number
- CN202380054313.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-22
- Filing Date
- 2023-07-04
- Publication Date
- 2025-03-07
AI Technical Summary
Polycrystal SiC molded bodies need to have high flatness in some applications, especially in plasma etching devices, and the prior art is difficult to effectively achieve their flatness.
By controlling the difference in area fractions of the region of the crystal plane orientation of a specific orientation between the first main surface and the second main surface in the polycrystalline SiC molded body, it is ensured to be less than 10.0% to reduce the intrinsic stress and warping.
The high flatness of the polycrystalline SiC molded body is achieved, and warping is reduced, and it is suitable for components that require high flatness such as plasma etching devices.
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Abstract
Description
Technical Field
[0001] The present invention relates to a polycrystalline SiC molded body and a method for producing the same. Background Art
[0002] SiC molded bodies have excellent properties such as heat resistance, corrosion resistance, and strength, and are used for various purposes. For example, Patent Documents 1 and 2 describe the use of SiC molded bodies as components for plasma etching devices such as edge rings, electrode plates, and heaters used in the manufacture of semiconductors.
[0003] Prior art literature
[0004] Patent Literature
[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-316821
[0006] Patent document 2: Japanese Patent Application Publication No. 2001-220237. Summary of the invention
[0007] Technical problem to be solved by the invention
[0008] Polycrystalline SiC molded bodies are sometimes required to have high flatness. For example, as described in Patent Documents 1 and 2, when a polycrystalline SiC molded body is used as a plasma etching component, in order to uniformly process the workpiece using plasma, the polycrystalline SiC molded body used as a plasma etching device component needs to have a flat surface.
[0009] Therefore, an object of the present invention is to provide a polycrystalline SiC molded body having excellent flatness and a method for producing the same.
[0010] Technical solutions for solving technical problems
[0011] The inventors of the present invention discovered that in a plate-shaped polycrystalline SiC molded body, the difference in area fraction of a region having a specific azimuthal crystal plane orientation between a first principal surface and a second principal surface parallel to the first principal surface is related to the flatness of the polycrystalline SiC molded body, and thus developed the present invention. That is, the present invention is achieved by the following matters.
[0012] <1> A substantially plate-shaped polycrystalline SiC molded body having a first main surface and a second main surface parallel to the first main surface,
[0013] The polycrystalline SiC molded body comprises:
[0014] The region R along the (200) plane orientation in the normal direction of the first main surface 200 ;
[0015] (311) plane oriented region R311 ;
[0016] (111) plane oriented region R 111 ;and
[0017] (220) plane oriented region R 220 ;as well as
[0018] The region R along the (200) plane orientation in the normal direction of the second main surface 200 ;
[0019] (311) plane oriented region R 311 ;
[0020] (111) plane oriented region R 111 ;and
[0021] (220) plane oriented region R 220 ,
[0022] Among them, area R XYZ The area fraction of
[0023] Region R XYZ Area / (area R 111 Area + Region R 200 Area + Region R 220 Area + Region R 311 area),
[0024] Among them, area R XYZ As region R 111 , Region R 200 , Region R 220 , Region R 311 Any one of
[0025] The polycrystalline SiC molded body is at least one of the following:
[0026] The area R in the first main surface 200 The area fraction of the second main surface area R 200 The difference in area fraction of is 10.0% or less; and
[0027] The area R in the first main surface 311 The area fraction of the second main surface area R 311 The difference in area fraction is 10.0% or less.
[0028] <2> according to <1> The polycrystalline SiC molded body is at least one of the following:
[0029] The area R in the first main surface 111The area fraction of the second main surface area R 111 The difference in area fraction of is 2.0% or less; and
[0030] The area R in the first main surface 220 The area fraction of the second main surface area R 220 The difference in area fraction is 2.0% or less.
[0031] <3> according to <1> or <2> The polycrystalline SiC molded body has an absolute value of BOW of 30 μm or less.
[0032] <4> A manufacturing <1> ~ <3> The method for producing a polycrystalline SiC molded body according to any one of the preceding claims, the method comprising forming a polycrystalline SiC layer film on a substrate by a CVD method,
[0033] When forming the polycrystalline SiC layer, the growth of the crystal is controlled so that the region R between the second main surface of the polycrystalline SiC layer and the first main surface of the polycrystalline SiC layer is 200 The difference in area fraction and the area R 311 At least one of the differences in area fractions is 10.0% or less.
[0034] Effects of the Invention
[0035] According to the present invention, a polycrystalline SiC molded body having excellent flatness and a method for producing the same are provided. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Figure 1 An example of an EBSD orientation map of a polycrystalline SiC molded body measured by the EBDS method is shown.
[0037] Figure 2 Schematic diagram showing an EBSD orientation map of a polycrystalline SiC molded body. DETAILED DESCRIPTION
[0038] The following detailed description of the present invention is one example of the embodiment, and the present invention is not limited to the embodiment.
[0039] The polycrystalline SiC molded body of the present embodiment is plate-shaped and has a first main surface and a second main surface parallel to the first main surface. The first main surface and the second main surface represent surfaces parallel to the surface of the substrate in CVD. The polycrystalline SiC molded body is at least one of the following: the region R of the first main surface 200 The area fraction of the second main surface R 200 The difference in area fraction of is 10.0% or less; and the region R of the first main surface 311 The area fraction of the second main surface R 311The difference in area fraction is 10.0% or less.
[0040] Region R 200 The difference in area fraction is calculated by "the area R in the first main surface 200 Area fraction of the second main surface" and "area fraction of the second main surface R 200 It is characterized by the “difference” in the “area fraction”.
[0041] Region R 311 The difference in area fraction is calculated by "the area R in the first main surface 311 Area fraction of the second main surface" and "area fraction of the second main surface R 311 It is characterized by the “difference” in the “area fraction”.
[0042] Here, "area fraction of a region" refers to the degree of orientation of a specific crystal plane. Specifically, "area fraction of a region" is as follows. In this specification, "area fraction of a region" refers to a value calculated based on the size of regions with the same orientation observed using the EBSD (Electron Backscatter Diffraction) method. Figure 1 An example of an EBSD orientation map of a polycrystalline SiC molded body measured by the EBSD method is shown. Here, "same orientation" refers to regions with the same crystal structure and the same orientation relative to the first principal surface or the second principal surface. Regions with the same orientation are represented by the same pattern in the EBSD orientation map. Figure 2 Schematic diagram showing an EBSD orientation map of a polycrystalline SiC molded body.
[0043] The "area fraction" of region A representing a specific orientation specifically refers to the value obtained by dividing the total area (SA) of the above-mentioned region A representing the same orientation in the entire area observed by the EBSD method by the sum of the areas of all observed orientations (A, B, C, D, etc.) (SA+SB+SC+SD...).
[0044] SA is the sum of the areas measured with the same orientation and pattern as area A.
[0045] SB is the sum of the areas measured with the same orientation and pattern as area B,
[0046] SC is the sum of the areas measured with the same orientation and pattern as area C.
[0047] SD is the sum of the areas of regions measured in the same orientation and pattern as region D.
[0048] Here, the measurement area of the entire area is appropriately adjusted to a square and rectangular area of 100μm×100μm to 500μm×500μm. By setting the measurement area to an area of 500μ×500μm or less, the total number of pixels in the area representing a specific crystal plane orientation can be increased, thereby improving the measurement accuracy. By setting the measurement area to an area of 100μm×100μm or more, the resolution of the entire measurement area can be maintained, thereby improving the measurement accuracy.
[0049] The “area fraction difference” of the region A refers to the difference between the “area fraction” of the region A on the first main surface and the “area fraction” of the region A on the second main surface.
[0050] The area fraction of the region showing a specific orientation can be measured by the method described in Examples below.
[0051] According to the present inventors' knowledge, by 200 The difference in area fraction, region R 311 By setting at least one of the differences in the area fractions of 1 and 2 to 10.0% or less, the warping of the SiC molded body can be suppressed. That is, a polycrystalline SiC molded body with high flatness can be realized.
[0052] There are various reasons why the polycrystalline SiC molded body warps. One of them is that the polycrystalline SiC molded body is deformed due to the inherent stress in the polycrystalline SiC molded body after being processed to be flat.
[0053] Although there are various reasons for the generation of intrinsic stress, the inventors found that one of the reasons is that the area fraction of the region representing a specific orientation on the first main surface is different from the area fraction of the region representing a specific orientation on the second main surface. The larger the difference, the greater the intrinsic stress, and thus warping occurs.
[0054] The polycrystalline SiC molded body becomes thicker by depositing polycrystalline SiC from the substrate surface, and in this process, when the area fraction of the region representing a specific orientation is different, compressive stress and tensile stress caused by the change in orientation are generated. If the area fraction of the region representing a specific orientation changes significantly, the generated compressive stress and tensile stress increase, and the resulting intrinsic stress increases, which in turn increases the degree of warping.
[0055] The polycrystalline SiC molded body is at least one of the following: Region R 111 The difference in area fraction of is 2.0% or less; and region R 220 The difference in area fraction is 2.0% or less.
[0056] Region R 111 The difference in area fraction is calculated by "the area R in the first main surface 111 Area fraction of the second main surface" and "area fraction of the second main surface R111 It is characterized by the “difference” in the “area fraction”.
[0057] Likewise, region R 220 The difference in area fraction is calculated by "the area R in the first main surface 220 Area fraction of the second main surface" and "area fraction of the second main surface R 220 It is characterized by the “difference” in the “area fraction”.
[0058] Preferably, the polycrystalline SiC molded body is in the shape of a disk. Preferably, the polycrystalline SiC molded body is in the shape of a disk with a diameter of 1.5 to 12 inches, and more preferably in the shape of a disk with a diameter of 4 to 9 inches. Since a processed body that can be used for a variety of purposes can be processed, the diameter is preferably 1.5 inches or more, and since the material properties of the molded body as a whole are uniform, the diameter is preferably 12 inches or less.
[0059] Preferably, the thickness of the polycrystalline SiC molded body is 0.10 mm to 7.00 mm. More preferably, it is 0.15 mm to 5.00 mm, and even more preferably, it is 0.30 to 3.00 mm. Since a polycrystalline SiC molded body that is easy to handle, such as reducing cracking during processing, can be obtained, it is preferably 0.10 mm or more, and since it can prevent the generation of cracks, etc., it is preferably 7.00 mm or less.
[0060] Preferably, the polycrystalline SiC molded body has a resistivity of 0.050 Ωcm or less, more preferably 0.020 Ωcm or less, and even more preferably 0.005 Ωcm or less.
[0061] By having such a resistivity, the polycrystalline SiC molded body can be preferably used in applications requiring high electrical conductivity.
[0062] The resistivity can be adjusted, for example, by doping the polycrystalline SiC molded body with nitrogen. The doping amount of nitrogen in the polycrystalline SiC molded body is, for example, 200 ppm (2.8×10 19 atoms / cm 3 ) or more, preferably 400 ppm (5.6×10 19 atoms / cm 3 ) or more, more preferably 1450ppm (2.0×10 20 atoms / cm 3 )above.
[0063] As described above, according to the present embodiment, since the polycrystalline SiC molded body is at least one of the following: the region R of the first main surface 200 The area fraction of the second main surface R 200 The difference in area fraction of is 10.0% or less; and the region R of the first main surface 311The area fraction of the second main surface R 311 Since the difference in area fraction of is 10.0% or less, the warping of the polycrystalline SiC molded body can be reduced.
[0064] Specifically, according to the present embodiment, when the polycrystalline SiC molded body is in a disk shape, a BOW of 30 μm or less in absolute value can be achieved.
[0065] It should be noted that BOW is a well-known parameter indicating the flatness of a disk-shaped substrate such as a silicon wafer. BOW will be described below.
[0066] BOW represents the distance between a plane (called a three-point reference plane) passing through three points set on the main surface of the polycrystalline SiC molded body substrate and the center point of the main surface of the polycrystalline SiC molded body substrate. The three points set to determine the three-point reference plane are set at positions that can form an equilateral triangle centered on the center of the main surface. In addition, the three points are set at positions about 3% inside the outer peripheral end diameter of the polycrystalline SiC substrate.
[0067] More specifically, the BOW value can be measured by FlatMaster 200 manufactured by Tropel Corporation.
[0068] (Manufacturing method)
[0069] The method for producing a polycrystalline SiC molded body according to the present embodiment will be described below by taking an example.
[0070] The polycrystalline SiC molded body of the present embodiment can be obtained by, for example, forming a polycrystalline SiC layer film on a substrate by a CVD method.
[0071] Specifically, first, a graphite substrate or the like is placed in a CVD furnace as a base material.
[0072] Then, a carrier gas, a raw material gas as a SiC supply source, and a nitrogen-containing gas are mixed, and the mixed gas is supplied to a CVD furnace. Thus, a polycrystalline SiC layer is formed on the substrate. In addition, nitrogen from the nitrogen-containing gas is doped into the polycrystalline SiC layer.
[0073] After the film is formed, the obtained polycrystalline SiC layer is separated from the substrate. Furthermore, the polycrystalline SiC layer is ground to obtain a polycrystalline SiC molded body.
[0074] Here, when forming the polycrystalline SiC layer film, the growth of the crystal is controlled so that the region R between the surface on the substrate side (e.g., the second main surface) of the polycrystalline SiC layer and the growth surface (e.g., the first main surface) of the polycrystalline SiC layer is 200 The difference in area fraction and the area R 311At least one of the differences in area fractions is 10.0% or less.
[0075] Specifically, by controlling the film forming temperature preferably within the range of 1100°C to 1900°C, more preferably within the range of 1200°C to 1600°C, controlling the residence time to 20 seconds to 45 seconds, controlling the positional relationship between the substrate and the gas nozzle so that the injection angle of the gas to the substrate plane is 5° to 55°, and controlling the nitrogen partial pressure to 10.0% to 60%, the region R can be made 200 The difference in area fraction and the area R 311 At least one of the differences in area fractions is 10.0% or less.
[0076] The carrier gas used in film formation is not particularly limited, and for example, hydrogen gas or the like can be used.
[0077] The raw material gas is not particularly limited as long as it is a gas that is a supply source containing Si and C. For example, a gas containing Si and C in its molecules, a mixed gas of a gas containing Si in its molecules and a hydrocarbon gas, etc. can be used.
[0078] The raw material gas, for example, in the case of a one-component system, includes methyltrichlorosilane, phenyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, etc. In the case of a two-component system, a mixture of silane-containing gas such as trichlorosilane and monosilane and a hydrocarbon gas can be mentioned.
[0079] After film formation, the growth surface side of the polycrystalline SiC molded body just after the polycrystalline SiC molded body layer is separated from the substrate is produced with unevenness, and a part of the separated substrate is attached to the substrate surface side. Since these residues will affect the warping, the growth surface side and the substrate surface side of the polycrystalline SiC molded body are appropriately ground to remove the unevenness and the residual substrate part. The grinding amount on the growth surface side and the grinding amount on the substrate surface side are appropriately adjusted to 20μm or more according to the degree of unevenness, the degree of the residual substrate part, the thickness of the polycrystalline SiC molded body before grinding, and the thickness of the polycrystalline SiC molded body required after grinding.
[0080] As described above, according to this embodiment, the control is performed so that the area R 200 The difference in area fraction, region R 311 At least one of the differences in area fractions of is 10.0% or less, so that the warpage of the polycrystalline SiC molded body can be reduced. Specifically, when the polycrystalline SiC molded body is disk-shaped, a BOW of 30 μm or less in absolute value can be achieved.
[0081] The polycrystalline SiC molded body of the present embodiment is preferably used for applications requiring flatness. For example, such applications include a support substrate for supporting a single crystal SiC layer. Alternatively, the polycrystalline SiC molded body is preferably used as a component for a plasma etching device used in semiconductor manufacturing. As such a component for a plasma etching device, an edge ring, an electrode plate, a heater, etc. can be listed. In addition, in semiconductor manufacturing, the polycrystalline SiC molded body can also be used as a virtual wafer used as a component for a semiconductor heat treatment device.
[0082] [Example]
[0083] In order to explain the present invention in more detail, examples performed by the present inventors are described below. However, the present invention should not be construed as being limited to the following examples.
[0084] (Example 1)
[0085] A graphite substrate with a diameter of 160 mm and a thickness of 5 mm was placed in a CVD furnace. Methyltrichlorosilane (raw material gas), hydrogen (carrier gas) and nitrogen were introduced into the CVD furnace to form a polycrystalline SiC film on the graphite substrate at 1400° C. for 10 hours.
[0086] The film forming conditions are shown in Table 1.
[0087] The gas residence time was 35 seconds. The gas residence time was calculated by the following formula.
[0088] (Formula 1): Gas residence time (seconds) = (furnace volume / gas flow rate) × ((20 + 273) / (reaction temperature + 273)) × 60
[0089] After film formation, the graphite substrate was taken out of the CVD furnace and peripheral processing and cutting processing were performed. The graphite substrate was then removed to obtain a polycrystalline SiC molded body with a diameter of 150 mm and a thickness of 0.6 mm. Then, in the plane grinding process, the first main surface and the second main surface were ground to obtain a polycrystalline SiC molded body with a diameter of 150 mm and a thickness of 0.4 mm. This was obtained as the polycrystalline SiC molded body of Example 1.
[0090] (Examples 2 to 6 and Comparative Examples 1 to 2)
[0091] Except that the conditions were changed as described in Table 1, the method described in Example 1 was followed to obtain a SiC molded body.
[0092] (Measurement of resistivity)
[0093] The volume resistivity of the polycrystalline SiC molded body was measured by a four-probe method using a "Loresta-GPMCT-T610" (Mitsubishi Chemical Analytech Co., Ltd.) as a measuring device.
[0094] Specifically, the probe of the measuring device was brought into contact with the first surface of the polycrystalline SiC molded body to measure the volume resistivity.
[0095] (Measurement of nitrogen concentration)
[0096] The nitrogen concentration in the polycrystalline SiC molded body was measured by secondary ion mass spectrometry. The measurement device used was "SIMS-4000" (ATOMIKA). The results are shown in Table 2.
[0097] (Measurement of the difference in area fraction)
[0098] The area R of the polycrystalline SiC molded bodies of Examples 1 to 6 and Comparative Examples 1 to 2 obtained was measured by the following method. 200 The difference in area fraction, region R 311 The difference in area fraction, region R 111 The difference in area fraction, region R 220 In addition, the difference in the area fraction of each crystal plane region is calculated by the "difference" between the "area fraction of each crystal plane region of the first main surface" and the "area fraction of each crystal region of the second main surface". The results are shown in Table 3.
[0099] (Measurement of the area fraction of each crystal plane)
[0100] The EBSD orientation maps of the polycrystalline SiC molded bodies obtained in Examples 1 to 6 and Comparative Examples 1 to 2 in the normal direction ±15° to the principal surface (hereinafter referred to as ND direction) were measured using DigiView manufactured by TSL Solutions Co., Ltd.
[0101] In the EBSD orientation map, the region R where the (111) plane of the 3C-type crystal structure SiC is oriented along the ND direction is extracted. 111 The area of the (200) plane is S(111). 200 The area of the (220) surface R 220 The area of the (311) surface R 311 The area of the crystal plane is also extracted as S(200), S(220), and S(311). Based on the extraction results, the area fraction of each crystal plane region in the measurement area of 300μm×300μm is calculated by the following calculation.
[0102] The area fraction of each crystal plane region =
[0103] Area of each crystal plane region / (S(111)+S(200)+S(220)+S(311))
[0104] The measurement conditions of the EBSD orientation map are as follows.
[0105] Pretreatment: mechanical grinding, carbon evaporation
[0106] Equipment: FE-SEM SU-70 manufactured by Hitachi High-Tech Corporation
[0107] EBSD DigiView manufactured by TSL Solutions Co., Ltd.
[0108] Measurement conditions: Voltage: 20kV
[0109] Tilt angle: 70°
[0110] Measuring area: 300μm×300μm
[0111] Measuring interval: 0.35μm
[0112] Evaluation target crystal system: 3C-type SiC (space group 216)
[0113] (BOW measurement)
[0114] BOW represents the distance between a plane passing through three points set on the main surface of the polycrystalline SiC substrate (called a three-point reference plane) and the center point of the main surface of the polycrystalline SiC substrate. The three points set to determine the three-point reference plane are set at positions that form an equilateral triangle centered on the center of the main surface. In addition, the three points are set at positions about 3% inside the outer peripheral end diameter of the polycrystalline SiC substrate.
[0115] More specifically, the BOW value can be measured by FlatMaster 200 manufactured by Tropel Corporation. The absolute values of the measured BOW values are shown in Table 3.
[0116] In addition, (111) / Total, (200) / Total, (220) / Total, and (311) / Total in Table 3 represent the area R 111 The difference in area fraction, region R 200 The difference in area fraction, region R 220 The difference in area fraction and the area R 311 The difference in area fractions.
[0117] As shown in Table 3, in region R 200The difference in area fraction, region R 311 A clear correlation can be seen between the difference in area fraction and BOW. 200 The difference in area fraction and R 311 When at least one of the differences in the area fractions of is within a range of 10.0% or less, a small BOW having an absolute value of 30 μm or less can be obtained.
[0118] As for region R 111 The difference in area fraction and the area R 220 When either of the area fractions is within a range of 2.0% or less, a small BOW with an absolute value of less than 30 μm can be obtained.
[0119] [Table 1]
[0120]
[0121] [Table 2]
[0122] Resistivity (Ω·cm) Nitrogen concentration (ppm) Example 1 0.005 930 Example 2 0.002 1550 Example 3 0.020 298 Example 4 0.010 524 Example 5 0.007 680 Example 6 0.003 1145 Comparative Example 1 0.001 2350 Comparative Example 2 0.100 140
[0123] [Table 3]
[0124]
[0125]
[0126] Industrial Applicability
[0127] A polycrystalline SiC molded body having excellent flatness can be provided as a component for a plasma etching device such as an edge ring, an electrode plate, and a heater used in manufacturing a semiconductor.
Claims
1. A substantially plate-shaped polycrystalline SiC molded body having a first main surface and a second main surface parallel to the first main surface, The polycrystalline SiC molded body comprises: The region R along the (200) plane orientation in the normal direction of the first main surface 200 ; (311) plane oriented region R 311 ; (111) plane oriented region R 111 ;and (220) plane oriented region R 220 ; as well as The region R along the (200) plane orientation in the normal direction of the second main surface 200 ; (311) plane oriented region R 311 ; (111) plane oriented region R 111 ;and (220) plane oriented region R 220 , Among them, area R XYZ The area fraction of Region R XYZ Area / (area R 111 Area + Region R 200 Area + Region R 220 Area + Region R 311 area), Among them, area R XYZ As region R 111 , Region R 200 , Region R 220 , Region R 311 Any one of The polycrystalline SiC molded body is at least one of the following: The area R in the first main surface 200 The area fraction of the second main surface area R 200 The difference in area fraction of is 10.0% or less; and The area R in the first main surface 311 The area fraction of the second main surface area R 311 The difference in area fraction is 10.0% or less.
2. The polycrystalline SiC molded body according to claim 1, wherein: The polycrystalline SiC molded body is at least one of the following: The area R in the first main surface 111 The area fraction of the second main surface area R 111 The difference in area fraction is less than 2.0%; as well as The area R in the first main surface 220 The area fraction of the second main surface area R 220 The difference in area fraction is 2.0% or less.
3. The polycrystalline SiC molded body according to claim 1 or 2, wherein: The absolute value of BOW is 30 μm or less.
4. A method for manufacturing the polycrystalline SiC molded body according to claim 1, the method comprising forming a polycrystalline SiC layer film on a substrate by a CVD method, in, When forming the polycrystalline SiC layer film, the growth of the crystal is controlled so that the region R between the second main surface of the polycrystalline SiC layer and the first main surface of the polycrystalline SiC layer 200 The difference in area fraction and the area R 311 At least one of the differences in area fractions is 10% or less.
Citation Information
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