Polycrystalline silicon carbide molded body and method for producing same

Abstract

The present invention provides: a plate-shaped polycrystalline silicon carbide molded body, wherein the nitrogen content is more than 1,000 ppm by mass and 5,000 ppm by mass or less, the resistivity is 0.0100 Ω·cm or less, the average difference value between the residual stress on a first main surface and the residual stress on a second main surface is 10-80 MPa as measured by an X-ray diffraction method, the thickness is 200-1,000 μm, and the warpage amount is 50 μm or less; and a method for producing same.

Description

Polycrystalline silicon carbide molded body and method for manufacturing the same

[0001] The present invention relates to a polycrystalline silicon carbide molded body and a method for producing the same.

[0002] Molded articles made of silicon carbide (SiC) (silicon carbide molded articles) have excellent properties such as heat resistance, corrosion resistance, and strength, and are used in a variety of applications. For example, Patent Documents 1 and 2 describe the use of silicon carbide as components for plasma etching equipment such as edge rings, electrode plates, and heaters used in semiconductor manufacturing.

[0003] Furthermore, Patent Document 3 discloses a semiconductor substrate comprising a single-crystal silicon carbide substrate and a polycrystalline silicon carbide substrate, wherein the single-crystal silicon carbide substrate and the polycrystalline silicon carbide substrate are bonded together via a predetermined interface layer.

[0004] Silicon carbide is a compound with strong covalent bonds, making it difficult to sinter. Therefore, it is difficult to obtain dense molded bodies using conventional sintering methods. Furthermore, when manufacturing silicon carbide molded bodies using sintering methods, a sintering aid is usually added to the powder raw material before sintering, making it difficult to obtain high-purity and high-density silicon carbide molded bodies.

[0005] For this reason, a manufacturing method utilizing the CVD (Chemical Vapor Deposition) method has been adopted as a method for producing silicon carbide molded bodies. The CVD method is a method of directly synthesizing a solid from a gas by supplying raw material gas onto a heated substrate and depositing a film. According to the CVD method, a dense molded body can be obtained without adding sintering aids. For example, Patent Document 4 discloses a technique for obtaining a polycrystalline silicon carbide molded body by the CVD method.

[0006] Japanese Patent Publication No. 2001-316821, Japanese Patent Publication No. 2001-220237, Japanese Patent No. 6387375, Japanese Patent No. 7155089

[0007] Polycrystalline silicon carbide molded bodies require various properties depending on their application. For example, as described in Patent Documents 1 and 2, when a polycrystalline silicon carbide molded body is used as a component for a plasma etching apparatus, a polycrystalline silicon carbide molded body with low resistivity is required in order to dissipate static electricity and generate plasma gas uniformly. Furthermore, when a polycrystalline silicon carbide molded body is used as a component for a plasma etching apparatus, a flat polycrystalline silicon carbide molded body is required.

[0008] Furthermore, as described in Patent Document 3, a flat polycrystalline silicon carbide molded body is necessary for joining a polycrystalline silicon carbide molded body to a single-crystal silicon carbide substrate. Also, when an electric current path is formed across the bonding surface between the polycrystalline silicon carbide molded body and the single-crystal silicon carbide layer, a polycrystalline silicon carbide molded body with low resistivity is required.

[0009] To meet these demands, a polycrystalline silicon carbide molded body with low resistivity and flatness has been proposed, as described in Patent Document 4.

[0010] The inventors of the present invention conceived of increasing the nitrogen content in the resulting polycrystalline silicon carbide molded body by introducing nitrogen gas into the atmosphere during the manufacturing of the polycrystalline silicon carbide molded body, in order to produce a polycrystalline silicon carbide molded body with low resistivity.

[0011] However, the inventors' investigations revealed that when the nitrogen content in the polycrystalline silicon carbide molded body exceeds 1000 ppm by mass, stacking faults tend to occur in the resulting polycrystalline silicon carbide molded body, and that the residual stress generated by these stacking faults causes warping of the polycrystalline silicon carbide molded body.

[0012] Furthermore, for polycrystalline silicon carbide molded bodies, for example, plate-like bodies with a thickness of 200 μm or more are required. However, because polycrystalline silicon carbide molded bodies have a bias in the growth pattern in the thickness direction, it has been found that when the polycrystalline silicon carbide molded body is a plate-like body with a thickness of 200 μm or more, (1) the nitrogen concentration in the resulting polycrystalline silicon carbide molded body tends to be uneven, (2) the desired nitrogen content cannot be reached, and (3) warping due to stacking faults is likely to occur.

[0013] The present invention has been made in view of the above circumstances, and the problem that the present invention aims to solve is to provide a polycrystalline silicon carbide molded body that is flat and has little warping despite having a high nitrogen content, low resistivity, and large thickness, and a method for manufacturing the same.

[0014] In order to solve the above problems, the inventors of the present invention conducted further investigations and found that the above-described polycrystalline silicon carbide molded body can be obtained by a specific manufacturing method. Based on this finding, the present invention is as follows: [1a] A polycrystalline silicon carbide molded body characterized in that it has a nitrogen content exceeding 1000 ppm by mass and 5000 ppm by mass or less, a resistivity of 0.0100 Ω・cm or less, an average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface at a position corresponding to the first main surface, measured by X-ray diffraction, is 10 MPa to 80 MPa, is a plate-like body having a thickness of 200 μm to 1000 μm, and has a warpage of 50 μm or less. [2a] The polycrystalline silicon carbide molded body according to [1a], wherein the average difference between the residual stress on the first main surface measured by X-ray diffraction and the residual stress on the second main surface at a position corresponding to the first main surface is 10 MPa to 70 MPa, and the coefficient of variation of the residual stress on the first main surface and the coefficient of variation of the residual stress on the second main surface measured by X-ray diffraction are both 2% to 20%. [3a] The polycrystalline silicon carbide molded body according to [1a] or [2a], wherein the amount of warpage is 5 μm to 50 μm.[4a] A method for producing a polycrystalline silicon carbide molded body according to any one of [1a] to [3a], comprising: a film formation step of introducing a mixed gas consisting of a raw material gas, nitrogen gas and a carrier gas and argon gas into an atmosphere and forming a polycrystalline silicon carbide film on a substrate by a CVD method; and a molding step of forming the polycrystalline silicon carbide film to obtain a polycrystalline silicon carbide molded body, wherein the film formation step of forming the polycrystalline silicon carbide film includes a first step and a second step, in which, with respect to the gas pressure of the entire gas consisting of the mixed gas and the argon gas, the mixed gas is introduced into the atmosphere at a first mixed gas partial pressure and the argon gas is introduced at a first argon gas partial pressure, and a first polycrystalline silicon carbide film is formed on the substrate, and then, In the second step, the partial pressure of the argon gas is decreased at a constant rate from the first partial pressure of the argon gas to the second partial pressure of the argon gas, while the partial pressure of the mixed gas is increased at a constant rate from the first partial pressure of the mixed gas to the second partial pressure of the mixed gas, while the mixed gas and the argon gas are introduced into the atmosphere to form a second silicon carbide film on the first polycrystalline silicon carbide film, wherein the partial pressure of the first argon gas is 30 kPa to 100 kPa, and in the first and second steps, the pressure of the total gas consisting of a mixed gas comprising a raw material gas, nitrogen gas, and carrier gas, and argon gas, is 95 kPa to 106 kPa.

[0015] In other words, the present invention is as follows. Note that the above [1a] to [4a] correspond to the following [1b] to [4b], respectively. [1b] A polycrystalline silicon carbide molded body in plate form, wherein the nitrogen content is greater than 1000 ppm by mass and 5000 ppm by mass or less, the resistivity is 0.0100 Ω・cm or less, the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface, measured by X-ray diffraction, is 10 MPa to 80 MPa, the thickness is 200 μm to 1000 μm, and the amount of warpage is 50 μm or less. [2b] The polycrystalline silicon carbide molded body according to [1b], wherein the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface, as measured by X-ray diffraction, is 10 MPa to 70 MPa, and the coefficient of variation of the residual stress on the first main surface and the coefficient of variation of the residual stress on the second main surface, as measured by X-ray diffraction, are independently 2% to 20%. [3b] The polycrystalline silicon carbide molded body according to [1b] or [2b], wherein the amount of warpage is 5 μm to 50 μm.[4b] A method for producing a polycrystalline silicon carbide molded body according to any one of [1b] to [3b], comprising the steps of: introducing a mixed gas consisting of a raw material gas, nitrogen gas, and a carrier gas, and argon gas into the atmosphere inside a CVD furnace to form a polycrystalline silicon carbide film on a substrate by a CVD method; and processing the polycrystalline silicon carbide film to obtain a polycrystalline silicon carbide molded body, wherein the step of forming the polycrystalline silicon carbide film comprises a first step and a second step, in which the mixed gas is introduced into the atmosphere inside a CVD furnace at a constant partial pressure of a first mixed gas, and argon gas is introduced into the atmosphere inside a CVD furnace at a constant partial pressure of a first argon gas to form a polycrystalline silicon carbide film on a substrate, A method comprising the following steps: in the second step, the mixed gas is introduced into the atmosphere of the CVD furnace while increasing the partial pressure of the mixed gas from the partial pressure of the first mixed gas to the partial pressure of the second mixed gas at a constant rate, and the argon gas is introduced into the atmosphere of the CVD furnace while decreasing the partial pressure of the argon gas from the partial pressure of the first argon gas to the partial pressure of the second argon gas at a constant rate, thereby forming a further polycrystalline silicon carbide film on the polycrystalline silicon carbide film formed in the first step, wherein the partial pressure of the first argon gas is 30 kPa to 100 kPa, and in the first and second steps, the pressure of the total gas, consisting of a mixed gas composed of a raw material gas, nitrogen gas, and carrier gas, and argon gas, is 95 kPa to 106 kPa.

[0016] According to the present invention, a flat polycrystalline silicon carbide molded body can be obtained that has a high nitrogen content, low resistivity, and large thickness, yet exhibits minimal warping.

[0017] This figure shows an example of a manufacturing apparatus for a polycrystalline silicon carbide molded body of the present invention. This figure shows an example of a measurement position for residual stress in a polycrystalline silicon carbide molded body of the present invention. This figure illustrates the process of forming a polycrystalline silicon carbide film in the manufacturing method of the present invention. This figure shows a radial cross-section of an isotropic graphite substrate on which a polycrystalline silicon carbide film is formed. This figure illustrates the process of obtaining a polycrystalline silicon carbide molded body from a laminate of an isotropic graphite substrate and a polycrystalline silicon carbide film.

[0018] First, the polycrystalline silicon carbide molded body of the present invention will be described. The polycrystalline silicon carbide molded body of the present invention is characterized by having a nitrogen content of more than 1,000 ppm by mass and 5,000 ppm by mass or less, a resistivity of 0.0100 Ω·cm or less, an average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface measured by X-ray diffraction of 10 MPa to 80 MPa, a thickness of 200 μm to 1,000 μm, and a warpage of 50 μm or less, and is a plate-like body.

[0019] The nitrogen content of the polycrystalline silicon carbide molded body (plate-like body) of the present invention is greater than 1,000 ppm by mass and less than or equal to 5,000 ppm by mass. Note that the nitrogen content value is relative to the entire polycrystalline silicon carbide molded body.

[0020] As the nitrogen content of a polycrystalline silicon carbide molded body increases, its resistivity decreases. Such polycrystalline silicon carbide molded bodies with low resistivity are suitable as components for plasma etching equipment. Therefore, the nitrogen content is preferably 1200 ppm by mass or more, more preferably 1400 ppm by mass or more, and even more preferably 1600 ppm by mass or more.

[0021] When the nitrogen content of a polycrystalline silicon carbide molded body is reduced, the amount of warping is reduced by suppressing stacking faults. Such a polycrystalline silicon carbide molded body with low warping is suitable as a component for plasma etching equipment. Therefore, the nitrogen content is preferably 4800 ppm by mass or less, more preferably 4600 ppm by mass or less, and even more preferably 4400 ppm by mass or less.

[0022] By adjusting the nitrogen content of the polycrystalline silicon carbide molded body of the present invention to within the above range, low resistivity and low warpage can be obtained. In this specification and the claims (hereinafter collectively referred to as "this specification"), the nitrogen content value in the polycrystalline silicon carbide molded body is a value measured and calculated by the following method.

[0023] (Measurement and calculation of nitrogen content) The approximate center portions of the first and second main surfaces of the polycrystalline silicon carbide molded body (plate-like body) are cut out, and the nitrogen content on the first main surface and the nitrogen content on the second main surface are measured once each using an ATOMIKA SIMS 4000. The arithmetic mean of these measurements is taken as the nitrogen content of the polycrystalline silicon carbide molded body.

[0024] In this specification, the main surface of a polycrystalline silicon carbide molded body (plate-like body) means the surface having the largest area of ​​the plate-like body. In this specification, the first main surface and the second main surface of a polycrystalline silicon carbide molded body (plate-like body) generally refer to the front surface and the back surface of the plate-like body. For example, if the first main surface is the front surface, then the second main surface is the other back surface. The reverse is also possible. That is, if the second main surface is the front surface, then the first main surface is the other back surface. Also, for example, the first main surface of a polycrystalline silicon carbide molded body is the main surface formed on the substrate side during manufacturing by the CVD method, and the second main surface of a polycrystalline silicon carbide molded body is the growth surface (the main surface opposite to the first main surface) during manufacturing by the CVD method. The reverse is also possible.

[0025] The silicon carbide crystals constituting the polycrystalline silicon carbide molded body of the present invention are thought to be composed of silicon carbide crystals in which some of the carbon atoms (C) in the silicon carbide crystals are replaced by nitrogen atoms (N), which are n-type dopants. It is believed that the replacement of carbon atoms (C) in silicon carbide with nitrogen atoms (N) increases the number of free electrons, thereby lowering the resistivity of the polycrystalline silicon carbide molded body.

[0026] The resistivity of the polycrystalline silicon carbide molded body (plate-like body) of the present invention is 0.0100 Ω·cm or less. When a polycrystalline silicon carbide molded body with low resistivity is used as a component for a plasma etching apparatus, it becomes easier to dissipate static electricity and generate plasma gas uniformly. For this reason, the resistivity is preferably 0.0070 Ω·cm or less, more preferably 0.0050 Ω·cm or less, and even more preferably 0.0030 Ω·cm or less.

[0027] The resistivity of the polycrystalline silicon carbide compact may be 0.0000 Ω·cm. However, from the viewpoint of ease of manufacturing the polycrystalline silicon carbide compact, the resistivity is preferably 0.0001 Ω·cm or more, more preferably 0.0002 Ω·cm or more, and even more preferably 0.0003 Ω·cm or more.

[0028] By adjusting the resistivity of the polycrystalline silicon carbide compact of the present invention within the above range, a polycrystalline silicon carbide compact suitable as a member for a plasma etching apparatus can be obtained. In the present specification, the value of the resistivity of the polycrystalline silicon carbide compact is a value measured and calculated by the following method.

[0029] (Measurement and calculation of resistivity) In accordance with JIS K7194, using "Loresta GP MCP-T610" manufactured by Mitsubishi Chemical Analytech Co., Ltd., the resistivity of the substantially central portions of the first main surface and the second main surface of the polycrystalline silicon carbide compact (plate-like body) is measured once each by the four-probe method, and the arithmetic mean value of these is taken as the resistivity of the polycrystalline silicon carbide compact.

[0030] As described above, generally, when the nitrogen content in the polycrystalline silicon carbide compact exceeds 1000 mass ppm, stacking defects are likely to occur in the polycrystalline silicon carbide compact, and warping occurs in the polycrystalline silicon carbide compact. However, the polycrystalline silicon carbide compact of the present invention can suppress warping even when the nitrogen content exceeds 1000 mass ppm because it is manufactured by the novel method of the present invention described later.

[0031] In the polycrystalline silicon carbide compact (plate-like body) of the present invention, the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface measured by the X-ray diffraction method is 10 MPa to 80 MPa.

[0032] From the viewpoints of suppressing the occurrence of warping and excellent flatness, the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface is preferably 70 MPa or less, more preferably 60 MPa or less, and even more preferably 50 MPa or less.

[0033] While a smaller average value is desirable for the difference between the residual stress on the first main surface and the residual stress on the second main surface, from the viewpoint of ease of manufacturing the polycrystalline silicon carbide molded body, the average value is preferably 10 MPa or higher, more preferably 20 MPa or higher, even more preferably 23 MPa or higher, and particularly preferably 25 MPa or higher.

[0034] By adjusting the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface to within the above range, warping can be suppressed and excellent flatness can be achieved.

[0035] In this specification, the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface of a polycrystalline silicon carbide molded body, measured by X-ray diffraction, is the arithmetic mean value measured and calculated by the following X-ray diffraction method: (A) calculate the residual stress at five locations on the first main surface; (B) calculate the residual stress at five locations on the second main surface corresponding to the five locations mentioned above; (C) calculate the absolute value of the difference between the residual stress on the first main surface and the residual stress on the second main surface at the corresponding positions obtained in (A) and (B); and (D) calculate the arithmetic mean value from the absolute values ​​of the differences at the five locations obtained in (C), and this is referred to as the "average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface, measured by X-ray diffraction."

[0036] For example, if the polycrystalline silicon carbide molded body is a plate-like body having a disc shape with a diameter of 150 mm (hereinafter sometimes abbreviated as "plate-like body 1"), the "five locations on the main surface" in (A) above are (1) 65 mm to the left radially from the center, (2) 30 mm to the left radially from the center, (3) the center, (4) 30 mm to the right radially from the center, and (5) 65 mm to the right radially from the center (Figure 2). The "five locations on the second main surface corresponding to the five locations" in (B) above are the locations where, when the polycrystalline silicon carbide molded body is placed on a horizontal surface with the first main surface in contact with it, perpendicular lines are drawn to the measurement positions of residual stress on the first main surface at the five locations (i.e., (1) to (5) above), and these perpendicular lines intersect with the second main surface (Figure 2). In Figure 2, the "first main surface" and the "second main surface" are referred to as "first surface" and "second surface," respectively.

[0037] If the polycrystalline silicon carbide molded body is a plate-like body having a disc shape with a diameter of 150 mm or less (hereinafter abbreviated as "plate-like body 2"), the "residual stress on the first main surface" and the "residual stress on the second main surface" are measured and calculated at five locations on plate-like body 2 that exist in the same proportion as the five locations on plate-like body 1 (Figure 2), and the "average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface, measured by X-ray diffraction" is calculated.

[0038] When the polycrystalline silicon carbide molded body is a rectangular plate-like body (hereinafter abbreviated as "plate-like body 3"), the "residual stress on the first main surface" and the "residual stress on the second main surface" are measured and calculated at five locations on plate-like body 3 that exist in the same proportion as the five locations on plate-like body 1 (Figure 2), and the "average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface, measured by X-ray diffraction" is calculated.

[0039] (Measurement and calculation of residual stress) Using the Rigaku SmartLab fully automated multi-purpose X-ray diffractometer under the following conditions, (i) measurement by X-ray diffraction and (ii) sin ２Using the ψ method, the residual stresses on the first major surface and the second major surface of the polycrystalline silicon carbide compact are calculated respectively. Under the following conditions, ψ represents the angle formed by the diffraction plane normal direction with respect to the sample surface normal direction. X-ray: Cu tube target, Kα, 40 kV, 20 mA Diffraction plane 2θ: 3C-SiC (511) plane Non-distorted angle: 133.60 degrees Scanning range: 129.20 degrees to 138.00 degrees Counting time: 270 seconds / ψ ψ angle measurement points: 7 points Young's modulus (E) of the polycrystalline silicon carbide compact: 450000 MPa Poisson's ratio (ν): 0.16 Measurement location (refer to Fig. 2 (when the polycrystalline silicon carbide compact is a plate having a disc shape with a diameter of 150 mm))

[0040] When the polycrystalline silicon carbide compact is a plate having a disc shape with a diameter of 150 mm (Fig. 2), at the above 5 locations, the residual stress (RS1 １ ~RS1 ５ ) on the first major surface and the residual stress (RS2 １ ~RS2 ５ ) on the second major surface, the absolute value of the difference therebetween, that is, |RS2 １ -RS1 １ |, |RS2 ２ -RS1 ２ |, |RS2 ３ -RS1 ３ |, |RS2 ４ -RS1 ４ |, and |RS2 ５ -RS1 ５ | are calculated, and the arithmetic mean value thereof is taken as the "average value of the difference between the residual stress on the first major surface and the residual stress on the second major surface measured by the X-ray diffraction method". In Fig. 2, "RS1 １ ~RS1 ５ " and "RS2 １ ~RS2 ５ " are described as "RS11~RS15" and "RS21~RS25" respectively.

[0041] In the polycrystalline silicon carbide molded body of the present invention, it is preferable that the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface, as measured by X-ray diffraction, is 10 MPa to 70 MPa, and that the coefficient of variation of the residual stress on the first main surface (hereinafter sometimes abbreviated as "CVRS1") and the coefficient of variation of the residual stress on the second main surface (hereinafter sometimes abbreviated as "CVRS2"), as measured by X-ray diffraction, are each independently 2% to 20%.

[0042] CVRS1 and CVRS2 are more preferably 19% or less and even more preferably 18% or less, independently of each other, in order to reduce warping. From the viewpoint of ease of manufacturing the polycrystalline silicon carbide molded body, CVRS1 and CVRS2 are more preferably 3% or more and even more preferably 4% or more, independently of each other. The values ​​of CVRS1 and CVRS2 may be the same or different.

[0043] By adjusting CVRS1 and CVRS2 within the above range, warping can be further reduced. In this specification, the values ​​of CVRS1 and CVRS2 are calculated by the following method.

[0044] (Calculation of CVRS1) The value of "CVRS1 (%)" is a value (%) calculated using the following formula with respect to the "arithmetic mean of residual stress on the first main surface" (hereinafter abbreviated as "mean value of RS1") and the "standard deviation of residual stress on the first main surface" (hereinafter abbreviated as "σRS1") (Note that the units of "σRS1" and "mean value of RS1" in the following formula are both "MPa"): CVRS1 (%) = 100 × (σRS1 / mean value of RS1)

[0045] Here, the average value of RS1 is calculated by the method described above for the residual stress at five locations on the first main surface (RS1 １ ~RS1 ５ ) is the arithmetic mean of ). Also, σRS1 is the value calculated from the following formula (where RS1 is used in the following formula). ｎ This refers to the residual stress at the five locations (n) on the first main surface (i.e., RS1 １ ~RS1５ ):

[0046]

[0047] (Calculation of CVRS2) The value of "CVRS2 (%)" is a value (%) calculated using the following formula with respect to the "arithmetic mean of residual stress on the second main surface" (hereinafter abbreviated as "mean value of RS2") and the "standard deviation of residual stress on the second main surface" (hereinafter abbreviated as "σRS2") (Note that the units of "σRS2" and "mean value of RS2" in the following formula are both "MPa"): CVRS2 (%) = 100 × (σRS2 / mean value of RS2)

[0048] Here, the average value of RS2 is calculated from the residual stress at five locations on the second main surface (RS2) calculated by the method described above. １ ~RS2 ５ ) is the arithmetic mean of ). Also, σRS² is the value calculated from the following formula (where RS² is used in the following formula). ｎ This refers to the residual stress at the five locations (n) on the second main surface (i.e., RS2 １ ~RS2 ５ ):

[0049]

[0050] The thickness of the polycrystalline silicon carbide molded body (plate-like body) of the present invention is 200 μm to 1000 μm. From the viewpoint of ease of handling of the polycrystalline silicon carbide molded body as a component for plasma etching equipment, the thickness is preferably 205 μm or more, more preferably 210 μm or more, and even more preferably 215 μm or more. Furthermore, from the viewpoint of reducing the resistivity in the thickness direction of the component for plasma etching equipment, the thickness is preferably 990 μm or less, more preferably 800 μm or less, and even more preferably 700 μm or less. Despite having sufficient thickness, the polycrystalline silicon carbide molded body of the present invention can suppress the occurrence of warping.

[0051] In this specification, the thickness value of the polycrystalline silicon carbide molded body is the arithmetic mean calculated by measuring the distance between the first main surface and the second main surface at the five locations described in the section on "Measurement and calculation of the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface" using a micrometer.

[0052] The curvature of the polycrystalline silicon carbide molded body (plate-like body) of the present invention is 50 μm or less. The curvature may be 0. Preferably, the curvature is between 5 μm and 50 μm.

[0053] While a smaller amount of warpage is preferable, from the viewpoint of ease of manufacturing the polycrystalline silicon carbide molded body, a value of 5 μm or more is preferable, 6 μm or more is more preferable, 7 μm or more is even preferable, and 8 μm or more is particularly preferable. Furthermore, since a smaller amount of warpage is preferable, a value of 49 μm or less is preferable, 48 μm or less is more preferable, and 47 μm or less is even preferable.

[0054] The polycrystalline silicon carbide molded body of the present invention exhibits low warping and excellent flatness despite having a high nitrogen content (over 1000 ppm by mass) and a large thickness (200 μm or more).

[0055] In this specification, the value of the warpage of the polycrystalline silicon carbide molded body is a value measured using an optical interference warpage measuring device (for example, the "FlatMaster 200XRA-Industrial" manufactured by Corning Tropel).

[0056] The silicon carbide in the polycrystalline silicon carbide molded body of the present invention adopts a polycrystalline crystalline form. Examples of such crystalline forms include the 3C type, 2H type, 4H type, 15R type, and others, which are polytypes (crystalline polymorphs) of SiC crystals. In this specification, the polycrystalline form of the silicon carbide molded body can be determined from the X-ray diffraction spectrum, and the content ratio of each polytype in the polycrystalline silicon carbide molded body can be calculated by the integrated intensity ratio of the main peaks obtained by X-ray diffraction.

[0057] The polycrystalline silicon carbide molded body of the present invention is a plate-like body. Its shape can be, for example, a disc shape, a flat plate shape, etc. When the polycrystalline silicon carbide molded body of the present invention has a disc shape, its diameter is preferably 100 mm to 360 mm, more preferably 125 mm to 340 mm, and even more preferably 130 mm to 320 mm. When the polycrystalline silicon carbide molded body of the present invention has a disc shape, its specific diameter can be, for example, 130 mm, 150 mm, 200 mm, or 300 mm, depending on its application.

[0058] The polycrystalline silicon carbide molded body of the present invention can be suitably manufactured by the manufacturing method of the present invention described later.

[0059] The polycrystalline silicon carbide molded body of the present invention can be suitably used in applications requiring high flatness and low resistivity. For example, the polycrystalline silicon carbide molded body of the present invention can be used as an edge ring, electrode plate, heater, etc., as a component for plasma etching equipment during semiconductor manufacturing. Furthermore, the polycrystalline silicon carbide molded body of the present invention can be used as a dummy wafer as a component for semiconductor heat treatment equipment during semiconductor manufacturing. When the polycrystalline silicon carbide molded body of the present invention is used as a dummy wafer, it is preferable that the polycrystalline silicon carbide molded body of the present invention has a thickness of, for example, about 300 μm to 1000 μm.

[0060] Next, a method for producing the polycrystalline silicon carbide molded body of the present invention (hereinafter sometimes abbreviated as "the manufacturing method of the present invention") will be described.

[0061] The manufacturing method of the present invention includes a step of forming a polycrystalline silicon carbide film on a substrate by CVD by introducing a mixed gas consisting of a raw material gas, nitrogen gas, and a carrier gas, and argon gas into the atmosphere inside a CVD furnace (hereinafter sometimes abbreviated as "film formation step"), and a step of processing the polycrystalline silicon carbide film to obtain a polycrystalline silicon carbide molded body (hereinafter sometimes abbreviated as "processing step"), wherein the film formation step includes a first step and a second step, in which the mixed gas is introduced into the atmosphere inside a CVD furnace at a constant partial pressure of a first mixed gas, and argon gas is introduced into the atmosphere inside a CVD furnace at a constant partial pressure of a first argon gas to form a polycrystalline silicon carbide film on a substrate, In the second step, the mixed gas is introduced into the atmosphere inside the CVD furnace while increasing the partial pressure of the mixed gas from the partial pressure of the first mixed gas to the partial pressure of the second mixed gas at a constant rate, and the argon gas is introduced into the atmosphere inside the CVD furnace while decreasing the partial pressure of the argon gas from the partial pressure of the first argon gas to the partial pressure of the second argon gas at a constant rate, thereby forming a further polycrystalline silicon carbide film on the polycrystalline silicon carbide film formed in the first step, characterized in that the partial pressure of the first argon gas is 30 kPa to 100 kPa, and in the first and second steps, the pressure of the total gas, consisting of a mixed gas composed of a raw material gas, nitrogen gas, and carrier gas, and argon gas, is 95 kPa to 106 kPa.

[0062] In the film deposition process, a mixed gas consisting of a raw material gas, nitrogen gas, and a carrier gas is used. The raw material gas is not particularly limited as long as it is a gas that supplies Si (silicon) and C (carbon), and may be a one-component gas (a gas containing both Si and C in its molecule) or a two-component gas (a mixture of a component gas containing Si in its molecule and a component gas containing C in its molecule). Furthermore, one-component gases may be used alone or in combination of two or more. Also, one-component gases and two-component gases may be used in combination. Furthermore, in a two-component gas, one component gas containing Si in its molecule may be used alone or in combination of two or more. Furthermore, in a two-component gas, one component gas containing C in its molecule may be used alone or in combination of two or more.

[0063] Examples of one-component gases include methyltrichlorosilane (MTS), trichlorophenylsilane, dichloromethylsilane, dichlorodimethylsilane, and chlorotrimethylsilane. Examples of two-component gases include mixtures of silane gas and hydrocarbon gas. Examples of silane gases include trichlorosilane and monosilane. Only one type of silane gas may be used, or two or more types may be used in combination.

[0064] The carrier gas used in the film deposition process is not particularly limited, but hydrogen gas is one example.

[0065] In the film deposition process, a mixed gas obtained by mixing the source gas, nitrogen gas, and carrier gas is introduced into the atmosphere inside the CVD furnace. For this mixing, a mixer can be used, for example.

[0066] In the film deposition process, argon gas is introduced into the atmosphere inside the CVD furnace. In this film deposition process, the nitrogen content and residual stress of the resulting polycrystalline silicon carbide molded body are adjusted by adjusting the supply amounts of the aforementioned mixed gas (i.e., a mixture of raw material gas, nitrogen gas, and carrier gas) and argon gas. Furthermore, the resistivity of the polycrystalline silicon carbide molded body is adjusted by adjusting its nitrogen content, and the warpage is adjusted by adjusting its residual stress.

[0067] Figure 1 shows an example of a manufacturing apparatus for a polycrystalline silicon carbide molded body according to the present invention. The manufacturing apparatus shown in Figure 1 is equipped with a CVD furnace 1 and a mixer 3. Carrier gas C, raw gas R which is the source of silicon carbide, and nitrogen gas N are supplied to the mixer 3 and mixed to produce a mixed gas. The mixed gas is supplied from the mixer 3 to the CVD furnace 1, in which a plurality of isotropic graphite substrates 2 are arranged. The shape of the isotropic graphite substrate 2 can be, for example, a disc shape. Argon gas Ar is supplied to the CVD furnace 1 along with the mixed gas.

[0068] The film deposition process may optionally include a third step, as described below, in addition to the first and second steps. As shown in Figure 3, the film deposition process is carried out sequentially in the first, second, and third (optional) steps.

[0069] The mixing ratios of the raw material gas, nitrogen gas, and carrier gas in the mixed gas supplied in the first, second, and third (optional) steps may differ, but from the viewpoint of controlling the amount of nitrogen absorbed by the resulting polycrystalline silicon carbide film, and the residual stress and warpage of the resulting polycrystalline silicon carbide molded body, it is preferable that the mixing ratios remain constant.

[0070] In the first, second, and third (optional) steps, independently, the ratio of the partial pressure of the raw material gas to the partial pressure of the mixed gas (i.e., a mixture of raw material gas, nitrogen gas, and carrier gas) (partial pressure of raw material gas / partial pressure of mixed gas) is preferably 0.01 to 0.10, more preferably 0.02 to 0.09, and even more preferably 0.03 to 0.08.

[0071] In the first, second, and third (optional) steps, independently, the ratio of the partial pressure of nitrogen gas to the partial pressure of the mixed gas (i.e., a mixture of raw material gas, nitrogen gas, and carrier gas) (partial pressure of nitrogen gas / partial pressure of mixed gas) is preferably 0.10 to 0.50, more preferably 0.15 to 0.45, and even more preferably 0.20 to 0.40.

[0072] In the first, second, and third (optional) steps, independently, the ratio of the partial pressure of the carrier gas to the partial pressure of the mixed gas (i.e., a mixture of raw material gas, nitrogen gas, and carrier gas) (partial pressure of carrier gas / partial pressure of mixed gas) is preferably 0.50 to 0.80, more preferably 0.55 to 0.75, and even more preferably 0.60 to 0.70.

[0073] In the first, second, and third (optional) steps, the atmospheric pressure inside the CVD furnace (i.e., the pressure of the total gas consisting of the mixed gas and argon gas) must be 95 kPa to 106 kPa. The pressure is preferably 96 kPa to 105 kPa, and more preferably 97 kPa to 104 kPa.

[0074] In the first step, a mixed gas is introduced into the atmosphere inside the CVD furnace at a constant partial pressure of a first mixed gas, and argon gas is introduced into the atmosphere inside the CVD furnace at a constant partial pressure of a first argon gas to form a polycrystalline silicon carbide film on the substrate.

[0075] Generally, in a mixed gas A consisting of gas 1 and gas 2, the partial pressure of gas 1 refers to the pressure when gas 1 occupies the same volume as mixed gas A on its own. The same applies to mixed gases with three or more components (for example, mixed gas B consisting of gas 1, gas 2, and gas 3). Also, according to Dalton's law of partial pressures, "pressure of mixed gas A" = "partial pressure of gas 1 + partial pressure of gas 2". Therefore, "pressure (partial pressure) of a mixed gas consisting of raw material gas, nitrogen gas, and carrier gas" = "partial pressure of raw material gas + partial pressure of nitrogen gas + partial pressure of carrier gas". Furthermore, "pressure of the total gas consisting of the mixed gas and argon gas" = "partial pressure of mixed gas + partial pressure of argon gas".

[0076] The partial pressure of the first mixed gas is preferably 5 kPa to 70 kPa, more preferably 10 kPa to 50 kPa, and even more preferably 15 kPa to 40 kPa.

[0077] The partial pressure of the first argon gas must be between 30 kPa and 100 kPa. Preferably, the partial pressure is between 40 kPa and 90 kPa, and more preferably between 50 kPa and 85 kPa.

[0078] The ratio of the partial pressure of the first argon gas to the pressure of the total gas consisting of the mixed gas and argon gas in the first step (partial pressure of the first argon gas / total gas pressure) is preferably 0.300 to 1.000, more preferably 0.400 to 0.900, and even more preferably 0.500 to 0.800.

[0079] The time t1 of the first step is not particularly limited, but is preferably more than 0% and 15% or less of the film formation time T (i.e., the sum of the time t1 of the first step, the time t2 of the second step, and the time t3 of the third step (optional step)), more preferably 2% to 12%, and even more preferably 3% to 10%.

[0080] In the first step, a polycrystalline silicon carbide film is formed on the substrate. When manufacturing using the manufacturing apparatus shown in Figure 1, a mixed gas and argon gas are supplied to the atmosphere inside the CVD furnace 1, and a polycrystalline silicon carbide film is formed on each isotropic graphite substrate 2 by the CVD method. In addition, nitrogen from the nitrogen-containing gas in the mixed gas is doped into the polycrystalline silicon carbide film. The exhaust gas Ex discharged after the reaction is sent to an exhaust gas treatment device (not shown).

[0081] In the second step following the first step, the mixed gas is introduced into the atmosphere inside the CVD furnace while increasing the partial pressure of the mixed gas from the partial pressure of the first mixed gas to the partial pressure of the second mixed gas at a constant rate, and the argon gas is introduced into the atmosphere inside the CVD furnace while decreasing the partial pressure of the argon gas from the partial pressure of the first argon gas to the partial pressure of the second argon gas at a constant rate, thereby forming a further polycrystalline silicon carbide film on the polycrystalline silicon carbide film formed in the first step.

[0082] The partial pressure of the second mixed gas is preferably 5.0 kPa to 101.3 kPa, more preferably 10.0 kPa to 90.0 kPa, and even more preferably 20.0 kPa to 80.0 kPa.

[0083] The partial pressure of the second argon gas is preferably 0.0 to 100.0 kPa, more preferably 0.5 kPa to 90.0 kPa, and even more preferably 1.0 kPa to 80.0 kPa.

[0084] At the end of the second step, the ratio of the partial pressure of the second argon gas to the pressure of the total gas, which consists of the mixed gas and argon gas (partial pressure of the second argon gas / total gas pressure), is preferably 0 to 1.000, more preferably 0.300 to 0.900, and even more preferably 0.500 to 0.800. A ratio of 0 means that the partial pressure of the second argon gas is 0.

[0085] In the second step, as shown in Figure 3, the partial pressure of the mixed gas is increased at a constant rate from the partial pressure of the first mixed gas to the partial pressure of the second mixed gas, and the partial pressure of the argon gas is decreased at a constant rate from the partial pressure of the first argon gas to the partial pressure of the second argon gas. In the second step, while changing the partial pressure of the mixed gas and the argon gas at a constant rate in this manner, the mixed gas and the argon gas are introduced into the atmosphere inside the CVD furnace to form another polycrystalline silicon carbide film on top of the polycrystalline silicon carbide film formed in the first step.

[0086] The ratio of the partial pressure of the first argon gas to the partial pressure of the nitrogen gas at the start of the first and second steps (partial pressure of the first argon gas / partial pressure of nitrogen gas) is preferably 1.0 or higher, more preferably 3.0 or higher, and even more preferably 5.0 or higher.

[0087] The ratio of the partial pressure of the first argon gas to the partial pressure of the nitrogen gas (partial pressure of the first argon gas / partial pressure of nitrogen gas) at the start of the first and second steps is not particularly limited, but is preferably 50.0 or less, more preferably 40.0 or less, and even more preferably 30.0 or less.

[0088] By adjusting the ratio of the partial pressure of the first argon gas to the partial pressure of the nitrogen gas at the start of the first and second steps so that it falls within the above range, the polycrystalline silicon carbide molded body of the present invention can be easily manufactured.

[0089] The time t2 of the second step is not particularly limited, but is preferably 70% or more and less than 100% of the film formation time T (i.e., the sum of the time t1 of the first step, the time t2 of the second step, and the time t3 of the third step (optional step)), more preferably 76% to 96%, and even more preferably 80% to 94%.

[0090] In the second step, a polycrystalline silicon carbide film is formed on top of the polycrystalline silicon carbide film formed in the first step. When manufacturing using the production apparatus shown in Figure 1, a mixed gas and argon gas are supplied to the atmosphere of the CVD furnace 1, and a polycrystalline silicon carbide film is formed on top of the polycrystalline silicon carbide film formed in the first step by the CVD method. In addition, nitrogen derived from the nitrogen gas in the mixed gas is doped into the polycrystalline silicon carbide film. The exhaust gas Ex discharged after the reaction is sent to an exhaust gas treatment device (not shown).

[0091] As mentioned above, when polycrystalline silicon carbide molded bodies are manufactured by the CVD method, if the nitrogen content in the polycrystalline silicon carbide molded body exceeds 1000 ppm by mass, stacking faults are more likely to occur in the resulting polycrystalline silicon carbide molded body, and warping occurs due to residual stress caused by such stacking faults.

[0092] Furthermore, when attempting to obtain a plate-like polycrystalline silicon carbide molded body with a thickness of 200 μm or more using the CVD method, warping occurs due to stacking faults in the resulting polycrystalline silicon carbide molded body, as there is a bias in the growth pattern in the thickness direction of the polycrystalline silicon carbide molded body.

[0093] In contrast, in the manufacturing method of the present invention, as described above, the partial pressure of the first argon gas at the start of the first and second steps is set to 30 kPa to 100 kPa, and in the second step, the partial pressure of the mixed gas and the partial pressure of the argon gas are changed at a constant rate while forming a polycrystalline silicon carbide film. This makes it possible to homogenize the degree to which stacking faults exist in the silicon carbide crystals, thereby reducing residual stress and resulting warping of the resulting polycrystalline silicon carbide molded body.

[0094] In other words, in the manufacturing method of the present invention, the partial pressure of the first argon gas at the start of the first and second steps is set to 30 kPa to 100 kPa, and in the second step, the partial pressure of the mixed gas (i.e., a mixture of raw material gas, nitrogen gas, and carrier gas) is increased by a constant rate, thereby increasing the amount of nitrogen incorporated into the resulting polycrystalline silicon carbide film by a constant rate, achieving a high nitrogen content, and as a result, a polycrystalline silicon carbide film with low resistivity can be obtained. Furthermore, in the manufacturing method of the present invention, residual stress is also reduced by the above-described processing, and a polycrystalline silicon carbide film with less warping can be obtained.

[0095] In the manufacturing method of the present invention, after the second step, as a third step, the mixed gas may be introduced into the atmosphere of the CVD furnace at a constant partial pressure of the second mixed gas, and the argon gas may be introduced into the atmosphere of the CVD furnace at a constant partial pressure of the second argon gas, thereby forming a further polycrystalline silicon carbide film on the polycrystalline silicon carbide film formed in the second step. However, the third step is an optional step and may not be performed.

[0096] In the third step, the partial pressure of the second mixed gas is preferably 80.0 kPa to 101.3 kPa, more preferably 90.0 kPa to 100.8 kPa, and even more preferably 95.0 kPa to 100.3 kPa.

[0097] In the third step, the partial pressure of the second argon gas is preferably 0 to 1.0 kPa, more preferably 0 to 0.5 kPa, and even more preferably 0 to 0.1 kPa. A partial pressure of 0 for the second argon gas means that no argon gas is supplied in the third step.

[0098] In the third step, the ratio of the partial pressure of the second argon gas to the pressure of the total gas, which consists of the mixed gas and argon gas (partial pressure of the second argon gas / total gas pressure), is preferably 0 to 0.010, more preferably 0 to 0.008, and even more preferably 0.000 to 0.006. A ratio of 0 means that the partial pressure of the second argon gas is 0, i.e., no argon gas is supplied in the third step.

[0099] The time t3 of the third step is not particularly limited, but is preferably 0 to 15%, more preferably 2% to 12%, and even more preferably 3% to 10% of the film formation time T (i.e., the sum of the time t1 of the first step, the time t2 of the second step, and the time t3 of the third step (optional step)).

[0100] In the manufacturing method of the present invention, the film formation time T (i.e., the sum of the time t1 of the first step, the time t2 of the second step, and the time t3 of the third step (optional step)) is not particularly limited, but is preferably 2 to 180 hours, more preferably 30 to 150 hours, and even more preferably 40 to 100 hours.

[0101] In the first, second, and third (optional) steps, the reaction temperature of the gas in the CVD furnace is preferably 1100°C to 1900°C, more preferably 1200°C to 1700°C, and even more preferably 1400°C to 1600°C.

[0102] In the manufacturing method of the present invention, a polycrystalline silicon carbide molded body is obtained by processing the polycrystalline silicon carbide film obtained in the film formation process. The specific processing steps and methods are described below.

[0103] A laminate of isotropic graphite substrate 2 and polycrystalline silicon carbide film is removed from the CVD furnace 1 of the manufacturing apparatus shown in Figure 1.

[0104] Figure 4 shows a radial cross-section of an isotropic graphite substrate 2 having a center line O-O', on which a polycrystalline silicon carbide film 4 is formed. Here, the polycrystalline silicon carbide film 4 is formed on the isotropic graphite substrate 2 so as to cover its entire surface.

[0105] To extract the desired polycrystalline silicon carbide molded body from the isotropic graphite substrate 2 on which the polycrystalline silicon carbide film 4 is formed, for example, the outer periphery is first processed. Specifically, along the break line A-A' shown in Figure 4, only the outer periphery of the isotropic graphite substrate 2 on which the polycrystalline silicon carbide film 4 is formed is removed.

[0106] Next, the isotropic graphite substrate 2, on which the polycrystalline silicon carbide film 4 is formed, is cut in two in the thickness direction along the line that divides the thickness of the isotropic graphite substrate 2 equally (i.e., the break line B-B' shown in Figure 4).

[0107] As a result, a laminate of isotropic graphite substrate 2 and polycrystalline silicon carbide film 4 is obtained, as shown on the left of Figure 5. Furthermore, only the isotropic graphite substrate 2 is removed from the laminate by oxidation, shot blasting, etc., to obtain the polycrystalline silicon carbide film 4, as shown in the center of Figure 5. Subsequently, the exposed surface of the polycrystalline silicon carbide film 4 is ground by grinding, etc. As a result, the desired polycrystalline silicon carbide molded body 10 is obtained, as shown on the right of Figure 5.

[0108] According to the present invention, a flat polycrystalline silicon carbide molded body can be obtained that has a high nitrogen content, low resistivity, and large thickness, yet exhibits minimal warping.

[0109] Next, the present invention will be described in more detail with reference to examples, but these are merely illustrative and not intended to limit the present invention.

[0110] (Example 1) An isotropic graphite substrate with a diameter of 160 mm and a thickness of 5 mm was placed inside a CVD furnace. The atmosphere inside the CVD furnace was composed of methyltrichlorosilane (MTS) gas (raw material gas) and nitrogen (N ２ ) gas, and hydrogen (H ２ A polycrystalline silicon carbide film was formed on an isotropic graphite substrate by introducing a mixed gas (hereinafter referred to as "mixed gas") consisting of a carrier gas and argon (Ar) gas, and heating at 1410°C for 80 hours. The film formation conditions are shown in Table 1.

[0111] The process was divided into three stages: the first 1.6 hours from the start of film deposition, the second 76.8 hours from the end of the first stage, and the third 1.6 hours from the end of the second stage. Throughout all stages, the pressure of the total gas, consisting of the mixed gas (i.e., a mixture of raw material gas, nitrogen gas, and carrier gas) and argon gas, was controlled to 101.3 kPa.

[0112] Throughout the entire process, the proportions of methyltrichlorosilane, nitrogen, and hydrogen in the mixed gas were kept constant (partial pressure ratio: methyltrichlorosilane:nitrogen:hydrogen = 0.05:0.62:0.33).

[0113] (First step) The partial pressure of the first mixed gas was kept constant at 20.2 kPa, and the partial pressure of the first argon gas was kept constant at 81.1 kPa.

[0114] (Second step) While maintaining a constant pressure of 101.3 kPa for the overall gas mixture (i.e., a mixture of raw material gas, nitrogen gas, and carrier gas) and argon gas, the partial pressure of the argon gas was decreased at a constant rate from the partial pressure of the first argon gas so that the partial pressure of the argon gas would be 0.0 kPa (partial pressure of the second argon gas) at the end of the second step. Furthermore, the partial pressure of the mixed gas was increased at a constant rate from the partial pressure of the first mixed gas so that the partial pressure of the mixed gas would be 101.3 kPa (partial pressure of the second mixed gas) at the end of the second step.

[0115] (Third step) The partial pressure of the second mixed gas was maintained at 101.3 kPa, and the partial pressure of the second argon gas was maintained at 0.0 kPa. In other words, no argon gas was supplied in the third step.

[0116] The partial pressures (kPa) of each gas at the start of the first and second processes, and the partial pressure of the first argon gas / partial pressure of nitrogen gas (indicated as "Ar / N" in the table below) ２ (This is indicated as follows), and the partial pressures (kPa) of each gas at the end of the second process and in the third process are listed in Table 1.

[0117] After the film deposition process, consisting of the first, second, and third steps, which totaled 80 hours, was completed, the laminate of the polycrystalline silicon carbide film and the isotropic graphite substrate was removed from the CVD furnace, and the outer perimeter was processed and the laminate was divided. Furthermore, the isotropic graphite substrate was removed to obtain a disc-shaped polycrystalline silicon carbide molded body with a diameter of 150 mm and a thickness of 510 μm.

[0118] The main surface of the obtained polycrystalline silicon carbide molded body on the isotropic graphite substrate side was designated as the first main surface, and the main surface on the opposite side (growth surface) was designated as the second main surface. By performing grinding and surface grinding processes of approximately 50 μm on the first main surface and the second main surface on the opposite side, a disc-shaped polycrystalline silicon carbide molded body with a diameter of 150 mm and a thickness of 410 μm was obtained.

[0119] The obtained molded body was confirmed to be a polycrystalline silicon carbide molded body by diffraction spectroscopy.

[0120] The nitrogen content (mass ppm), resistivity (Ω·cm), thickness (μm), and warpage (μm) of the obtained polycrystalline silicon carbide molded body were measured and calculated. The results are shown in Table 2.

[0121] The average value (MPa) of the difference between the residual stress on the first main surface (the main surface on the isotropic graphite substrate side during the above manufacturing process) and the residual stress on the second main surface (the main surface opposite to the first main surface), the coefficient of variation of the residual stress on the first main surface (CVRS1), and the coefficient of variation of the residual stress on the second main surface (CVRS2) were calculated by X-ray diffraction of the obtained polycrystalline silicon carbide molded body. The results are shown in Table 3.

[0122] Although not shown in Table 3, after all evaluations were completed, the first and second main surfaces of the 410 μm thick disc-shaped polycrystalline silicon carbide molded body were subjected to additional grinding and surface grinding of approximately 50 μm each, respectively, to obtain a 310 μm thick disc-shaped polycrystalline silicon carbide molded body. The average values ​​of the difference between the residual stress on the first main surface and the residual stress on the second main surface of the 310 μm thick disc-shaped polycrystalline silicon carbide molded body, CVRS1 and CVRS2, were confirmed to be the same as those for the 410 μm thick disc-shaped polycrystalline silicon carbide molded body.

[0123] A disc-shaped polycrystalline silicon carbide molded body with a thickness of 310 μm was subjected to an additional grinding process of approximately 50 μm on the first main surface and the second main surface, respectively, to obtain a disc-shaped polycrystalline silicon carbide molded body with a thickness of 210 μm. The average values ​​of the difference between the residual stress on the first main surface and the residual stress on the second main surface of the 310 μm thick disc-shaped polycrystalline silicon carbide molded body, CVRS1 and CVRS2, were confirmed to be the same as those for a disc-shaped polycrystalline silicon carbide molded body with a thickness of 410 μm.

[0124] (Examples 2-4 and Comparative Example 4) Except for changing the partial pressures of each gas to those listed in Table 1, a disc-shaped polycrystalline silicon carbide molded body with a diameter of 150 mm was obtained in the same manner as in Example 1.

[0125] The obtained molded body was confirmed to be a polycrystalline silicon carbide molded body by diffraction spectroscopy.

[0126] The nitrogen content (mass ppm), resistivity (Ω·cm), thickness (μm), and warpage (μm) of the obtained polycrystalline silicon carbide molded body were calculated. The results are shown in Table 2.

[0127] The average value (MPa) of the difference between the residual stress on the first main surface (the main surface on the isotropic graphite substrate side during the above manufacturing process) and the residual stress on the second main surface (the main surface opposite to the first main surface), the coefficient of variation of the residual stress on the first main surface (CVRS1), and the coefficient of variation of the residual stress on the second main surface (CVRS2) were calculated by X-ray diffraction of the obtained polycrystalline silicon carbide molded body. The results are shown in Table 3.

[0128] (Comparative Examples 1-3) Except for changing the partial pressures of each gas to those listed in Table 1, a disc-shaped polycrystalline silicon carbide molded body with a diameter of 150 mm was obtained in the same manner as in Example 1.

[0129] The obtained molded body was confirmed to be a polycrystalline silicon carbide molded body by diffraction spectroscopy.

[0130] The nitrogen content (mass ppm), resistivity (Ω·cm), thickness (μm), and warpage (μm) of the obtained polycrystalline silicon carbide molded body were calculated. The results are shown in Table 2.

[0131] The average value (MPa) of the difference between the residual stress on the first main surface (the main surface on the isotropic graphite substrate side during the above manufacturing process) and the residual stress on the second main surface (the main surface opposite to the first main surface), the coefficient of variation of the residual stress on the first main surface (CVRS1), and the coefficient of variation of the residual stress on the second main surface (CVRS2) were calculated by X-ray diffraction of the obtained polycrystalline silicon carbide molded body. The results are shown in Table 3.

[0132]

[0133]

[0134]

[0135] As shown in the results in Table 2, the polycrystalline silicon carbide molded bodies of Examples 1 to 4 had a high nitrogen content, resulting in low resistivity. Furthermore, as shown in the results in Table 2, despite the high nitrogen content and large thickness, the polycrystalline silicon carbide molded bodies of Examples 1 to 4 exhibited suppressed warping and excellent flatness.

[0136] On the other hand, as shown in the results in Table 2, the polycrystalline silicon carbide molded bodies of Comparative Examples 1 and 2 had a low nitrogen content, resulting in high resistivity. Also, as shown in the results in Table 2, the polycrystalline silicon carbide molded bodies of Comparative Examples 3 and 4 had a large amount of warping and poor flatness.

[0137] According to the present invention, a flat polycrystalline silicon carbide molded body can be obtained that has a high nitrogen content, low resistivity, and large thickness, yet exhibits minimal warping. The polycrystalline silicon carbide molded body of the present invention is useful as a component for plasma etching equipment and the like.

[0138] This application is based on Japanese Patent Application No. 2024-171212, which is entirely contained herein.

[0139] 1 CVD furnace 2 Isotropic graphite substrate 3 Mixer 4 Polycrystalline silicon carbide film 10 Polycrystalline silicon carbide molded body Ar Argon gas C Carrier gas R Raw material gas N Nitrogen gas A-A' Fracture line B-B' Fracture line O-O' Center line

Claims

1. A polycrystalline silicon carbide molded body in plate form, wherein the nitrogen content is greater than 1,000 ppm by mass and less than or equal to 5,000 ppm by mass, the resistivity is 0.0100 Ω·cm or less, the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface, as measured by X-ray diffraction, is 10 MPa to 80 MPa, the thickness is 200 μm to 1,000 μm, and the warpage is 50 μm or less.

2. The polycrystalline silicon carbide molded body according to claim 1, wherein the average value of the difference between the residual stress on the first main surface and the residual stress on the second main surface, as measured by X-ray diffraction, is 10 MPa to 70 MPa, and the coefficients of variation of the residual stress on the first main surface and the coefficients of variation of the residual stress on the second main surface, as measured by X-ray diffraction, are independently 2% to 20%.

3. The polycrystalline silicon carbide molded body according to claim 1 or 2, wherein the amount of warpage is 5 μm to 50 μm.

4. A method for producing a polycrystalline silicon carbide molded body according to claim 1 or 2, comprising the steps of: introducing a mixed gas consisting of a raw material gas, nitrogen gas, and a carrier gas, and argon gas into the atmosphere inside a CVD furnace to form a polycrystalline silicon carbide film on a substrate by a CVD method; and processing the polycrystalline silicon carbide film to obtain a polycrystalline silicon carbide molded body, wherein the step of forming the polycrystalline silicon carbide film comprises a first step and a second step, in which the mixed gas is introduced into the atmosphere inside a CVD furnace at a constant partial pressure of a first mixed gas, and argon gas is introduced into the atmosphere inside a CVD furnace at a constant partial pressure of a first argon gas to form a polycrystalline silicon carbide film on a substrate, A method comprising the following steps: in the second step, the mixed gas is introduced into the atmosphere of the CVD furnace while increasing the partial pressure of the mixed gas from the partial pressure of the first mixed gas to the partial pressure of the second mixed gas at a constant rate, and the argon gas is introduced into the atmosphere of the CVD furnace while decreasing the partial pressure of the argon gas from the partial pressure of the first argon gas to the partial pressure of the second argon gas at a constant rate, thereby forming a further polycrystalline silicon carbide film on the polycrystalline silicon carbide film formed in the first step, wherein the partial pressure of the first argon gas is 30 kPa to 100 kPa, and in the first and second steps, the pressure of the total gas, consisting of a mixed gas composed of a raw material gas, nitrogen gas, and carrier gas, and argon gas, is 95 kPa to 106 kPa.

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