Method for manufacturing a silicon carbide polycrystalline film

Abstract

The present invention provides a method for producing polycrystalline silicon carbide films that can improve the productivity of such films. [Solution] A method for manufacturing a silicon carbide polycrystalline film, comprising a second film formation step of forming a second silicon carbide polycrystalline film at a predetermined position on a second support substrate having a film formation surface whose curvature is adjusted based on the curvature of the surface of a first silicon carbide polycrystalline film obtained by forming a film formation surface at a predetermined position on the film formation surface of a first support substrate having a film formation surface whose curvature has been confirmed in advance.

Description

[Technical Field]

[0001] This invention relates to a method for producing a silicon carbide polycrystalline film. [Background technology]

[0002] In the manufacturing method of silicon carbide polycrystalline substrates, techniques are known to reduce the amount of warping that occurs in silicon carbide polycrystalline films formed by the CVD (Chemical Vapor Deposition) method. Patent Document 1 discloses a technique to reduce the amount of warping in the concave direction that occurs in the silicon carbide polycrystalline film when the graphite support substrate is burned and separated after the silicon carbide polycrystalline film is formed, by making the upper and lower surfaces of the graphite support substrate convex curved surfaces. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-251062 [Patent Document 2] Japanese Patent Publication No. 2021-116465 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In a silicon carbide polycrystalline film deposition apparatus, the deposition process is controlled to ensure uniformity of conditions such as the concentration, flow rate, and uniformity of the raw material gas and dopant gas, as well as the temperature within the deposition chamber. This is achieved by controlling the shape of the deposition chamber where the silicon carbide polycrystalline film is deposited onto the support substrate, and the shape and arrangement of components such as substrate holders that hold the support substrate within the deposition chamber. However, these conditions become locally non-uniform within the deposition chamber. Therefore, the amount of warpage of the deposited silicon carbide polycrystalline film varies depending on the position where the support substrate is placed within the deposition chamber. While there is no problem if the amount of warpage of the silicon carbide polycrystalline film is within the acceptable range, it is considered a defective product if the amount of warpage is outside the acceptable range. Therefore, the production of silicon carbide polycrystalline films with warpage outside the acceptable range within the same batch leads to a decrease in the productivity of silicon carbide polycrystalline film deposition. Therefore, it is desirable to avoid the production of silicon carbide polycrystalline films with warping outside the acceptable range and to improve the productivity of silicon carbide polycrystalline films.

[0005] The present invention aims to provide a method for producing a silicon carbide polycrystalline film that can improve the productivity of silicon carbide polycrystalline films in order to solve the above problems. [Means for solving the problem]

[0006] To solve the above problems, the present invention provides a method for manufacturing a silicon carbide polycrystalline film, which includes a second film deposition step in which a second silicon carbide polycrystalline film is deposited at a predetermined position on a second support substrate having a film deposition surface whose curvature is adjusted based on the curvature of the surface of a first silicon carbide polycrystalline film obtained by depositing a film deposition surface at a predetermined position on a first support substrate having a film deposition surface whose curvature has been confirmed in advance. [Effects of the Invention]

[0007] The present invention provides a method for producing a silicon carbide polycrystalline film that can improve the productivity of silicon carbide polycrystalline films. [Brief explanation of the drawing]

[0008] [Figure 1] It is a flowchart of a method for manufacturing a silicon carbide polycrystalline film according to an embodiment. [Figure 2] It is a schematic perspective view of the first support substrate 100. [Figure 3] It is a schematic view of a film forming apparatus in a state where the first support substrate is disposed in a film forming chamber. [Figure 4] It is a schematic cross-sectional view of the first silicon carbide polycrystalline film 400 in the first film forming step S103, the first grinding step S104, and the first removing step S105. [Figure 5] It is an explanatory diagram supplementing the description of the first warpage measurement step S201. [Figure 6] It is a scatter diagram obtained by representing, as points, the warpage amount of the surface of the first silicon carbide polycrystalline film with respect to the curvature amount of the film forming target surface of the first support substrate, and is a graph in which a straight line of a linear regression obtained based on the scatter diagram is indicated by a dotted line. [Figure 7] It is a schematic perspective view of the second support substrate 700. [Figure 8] It is a schematic view of a film forming apparatus in a state where the second support substrate 700 is disposed in a film forming chamber. [Figure 9] It is a schematic cross-sectional view of the second silicon carbide polycrystalline film 800 in the second film forming step S303, the second grinding step S304, and the second removing step S305. [Figure 10] It is an explanatory diagram supplementing the description of the second warpage measurement step. [Figure 11] It is a schematic view showing the disposition state of the first support substrate in a film forming chamber in an embodiment of a modification, and the warpage amount of the surface of the first silicon carbide polycrystalline film formed on the film forming target surface of the first support substrate in that disposition state.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, an embodiment of a method for manufacturing a silicon carbide polycrystalline film will be described with reference to the drawings.

[0010] [Method for Manufacturing Silicon Carbide Polycrystalline Film] Figure 1 is a flow chart of a method for manufacturing a silicon carbide polycrystalline film according to an embodiment. The purpose of the silicon carbide polycrystalline film manufacturing method is to avoid the production of silicon carbide polycrystalline films with surface curvature outside the acceptable range, and to improve the productivity of silicon carbide polycrystalline films by adjusting the curvature of the film deposition surface of the support substrate so that the surface curvature of all silicon carbide polycrystalline films obtained per batch is within the acceptable range.

[0011] To achieve this objective, the manufacturing flow can be divided into three stages: a prototype stage S100 of a silicon carbide polycrystalline film; an adjustment stage S200 in which the curvature of the surface of the silicon carbide polycrystalline film obtained in the prototype stage S100 is measured and evaluated, and the curvature of the film-forming surface of the support substrate is adjusted based on the evaluated curvature; and a manufacturing stage S300 in which the silicon carbide polycrystalline film is manufactured using the support substrate whose curvature of the film-forming surface has been adjusted in the adjustment stage S200, so that the curvature of the surface of all silicon carbide polycrystalline films obtained per batch is within an acceptable range.

[0012] <Prototype stage S100> The prototype stage S100 is a stage in which a silicon carbide polycrystalline film is produced as a prototype before mass production of the silicon carbide polycrystalline film in the manufacturing stage S300, in order to prevent the production of silicon carbide polycrystalline films with surface warping outside the acceptable range in the manufacturing stage S300. The prototype stage S100 can be performed before the manufacturing stage S300 when a new film deposition apparatus is introduced and silicon carbide polycrystalline film is deposited for the first time using it, or when an existing film deposition apparatus is used but there are any changes to the existing film deposition conditions, such as the introduction conditions of the raw material gas and carrier gas, the temperature and pressure atmosphere during film deposition, the replacement of the substrate holder, or the rotation speed of the support substrate. The prototype stage S100 includes, for example, the following steps.

[0013] (First support substrate preparation step S101) The first support substrate preparation step S101 is a step in which the first support substrate 100 for prototyping is prepared. Specifically, it is confirmed that there are no defects such as scratches in the support substrate for the silicon carbide polycrystalline film, and one or more disc-shaped thin films are selected.

[0014] As the first support substrate 100, for example, a disc-shaped silicon substrate or graphite substrate with a thickness of 0.05 mm to 5.0 mm and a diameter of 4 inches to 10 inches (preferably 6 to 10 inches in diameter, more preferably 8 to 10 inches in diameter) can be used. The diameter of the first support substrate 100 itself may be 5 to 20 mm larger so that the diameter after the outer diameter processing of the deposited silicon carbide polycrystalline film is the above diameter. Figure 2 shows a schematic perspective view of the first support substrate 100. The first support substrate 100 has a surface 101, a back surface 102, and a side surface 103. A silicon carbide polycrystalline film is deposited on the surface 101 and back surface 102, which are the surfaces to be film-deposited, by the CVD method. Although the side surface 103 is not intended for film deposition, it is also film-deposited by the film deposition process on the surface 101 and back surface 102.

[0015] The surface 101 and the back surface 102 may be curved into a concave or convex shape, or they may be flat, or they may have a shape that combines curvature and flatness, allowing for the deposition of a silicon carbide polycrystalline film.

[0016] The shapes of the front surface 101 and back surface 102 of the first support substrate 100 may be set to be flat surfaces without curvature, or they may be set to curved surfaces or flat surfaces with individually different shapes. It is preferable to record the curvature of the front surface 101 and back surface 102 of the first support substrate 100 in advance, and this record can be used to determine the curvature of the front surface 701 and back surface 702 of the second support substrate 700, which will be the surfaces to be coated with film as described later.

[0017] • First curvature measurement process The curvature of the front surface 101 and back surface 102 of the first support substrate 100 does not need to be measured if it is known in advance, but it may be measured as needed if the curvature is unknown or as a precautionary check.

[0018] A purchased product may be used as the first support substrate 100, but for example, the front and back surfaces of a graphite disc with a thickness of 300 μm to 10 mm, cut in parallel, may be ground and polished and used as the first support substrate 100.

[0019] When multiple first support substrates 100 are prepared, it is preferable to ensure that the curvature of their surface 101 and back surface 102 are all the same, for example, by making them all flat. For example, if it is anticipated that the polycrystalline silicon carbide film deposited using the first support substrate 100 will have a concave shape, the surface 101 and back surface 102 of the first support substrate 10 may be set to a convex shape, or if it is anticipated that the polycrystalline silicon carbide film will have a convex shape, the surface 101 and back surface 102 of the first support substrate 100 may be set to a concave shape, or other predetermined curved surfaces other than flat surfaces.

[0020] When the front surface 101 and back surface 102 of the first support substrate 100 are curved surfaces with a convex or concave shape, the height difference (amount of warpage) of the curved surfaces can be set to approximately 0.05 mm to 1 mm. The amount of warpage is the height difference of the curved surfaces when the front surface 101 and back surface 102 are curved surfaces. For measuring the amount of warpage, for example, an electron microscope or a precision shape measuring machine using laser measurement can be used.

[0021] In this embodiment, the shape of curved surfaces such as the front surface 101 and the back surface 102 will be described using the example of adjusting the curvature by evaluating the measured amount of warping, but the present invention is not limited to this. For example, in order to evaluate the amount of warping used to adjust the shape of a curved surface, in addition to the directly measured amount of warping, values ​​of other parameters such as the radius of curvature, surface roughness, and waviness can also be used.

[0022] Furthermore, in this embodiment, the example shows a case where both the front surface 101 and the back surface 102 of the first support substrate 100 are used as film deposition surfaces, and a silicon carbide polycrystalline film is deposited on both of these surfaces. However, the present invention is not limited to this. For example, the silicon carbide polycrystalline film may be deposited on only one of the front surface 101 and the back surface 102 of the first support substrate 100.

[0023] (First support substrate placement process in furnace S102) Step S102, the first support substrate placement step, is the step of placing the first support substrate 100 inside the furnace of the film deposition apparatus (hereinafter, "furnace" may be referred to as "film deposition chamber"). Only one first support substrate 100 may be placed inside the furnace, or multiple first support substrates 100 may be placed inside. As the film deposition apparatus, for example, the film deposition apparatus described in Patent Document 2 can be used, so in this specification, a detailed explanation of the film deposition apparatus will be omitted by referring to Patent Document 2. Figure 3 is a schematic diagram of the film deposition apparatus in which the first support substrate is placed inside the film deposition chamber.

[0024] As shown in Figure 3, the film deposition apparatus 1000 includes a film deposition chamber 1001 for depositing a silicon carbide polycrystalline film, a gas supply pipe 1002 for supplying raw material gas and carrier gas to the film deposition chamber 1001, a gas supply volume control valve 1003 for adjusting the amount of gas supplied through the gas supply pipe 1002, a gas exhaust pipe 1004 for exhausting gas from the film deposition chamber 1001, a gas exhaust volume control valve 1005 for adjusting the amount of gas exhausted through the gas exhaust pipe 1004, and a temperature control device 1006 such as a heater for adjusting the temperature inside the film deposition chamber 1001.

[0025] Multiple first support substrates 100 can be arranged inside the film deposition chamber 1001 by holding the first support substrate 100 in a substrate holder (not shown). In Figure 3, the arrangement of multiple first support substrates in the horizontal direction is represented by the first support substrate 100 at the left end, the first support substrate 100a positioned a position from the left, the space between the first support substrate 100 and the first support substrate 100a, and the space between the first support substrate 100a and the temperature control device 1006, indicated by "...". Furthermore, the position in the substrate holder where the first support substrate 100 is arranged is designated as the first position 1100, and the position a position from the left where the first support substrate 100a is arranged is designated as the a position 1100a.

[0026] An example of the first support substrate placement process S102 is to first place one or more first support substrates, within the number that can be accommodated in the substrate holder, and then place the substrate holder together with the placed first support substrates into the deposition chamber 1001. When multiple first support substrates are placed, it is preferable to place the first support substrates in a row at equal intervals such that the surfaces to be deposited are parallel and the centers of the substrates are on the same straight line, in order to improve the unevenness of the silicon carbide polycrystalline film deposition and make the film thickness as uniform as possible.

[0027] The curvature of the film-forming surfaces of the multiple first support substrates 100 may all be set to the same amount and arranged accordingly. However, unevenness in the deposition of the silicon carbide polycrystalline film may be anticipated depending on the position where the first support substrates are arranged within the deposition chamber 1001 (for example, the first position 1100 and the a position 1100a). In such cases, the curvature of the film-forming surfaces of the first support substrates 100 may be set to an appropriate amount according to predetermined positions. Examples of this include setting the surface 101 as a flat surface without curvature and the back surface 102 as a curved convex surface, or setting any of the surfaces as a flat surface, a convex surface, or a concave surface.

[0028] Furthermore, it is preferable to pre-record necessary information such as predetermined positions for arranging the first support substrate within the deposition chamber 1001 (for example, the first position 1100 and the a-position 1100a), and the curvature of the surface to be deposited on each of the first support substrates. This record can be used to determine the curvature of the front surface 701 and back surface 702, which will be the surface to be deposited on the second support substrate 700, as described later.

[0029] (First film formation step S103) Figure 4 is a schematic cross-sectional view of the first silicon carbide polycrystalline film 400 during the first film formation process S103, the first grinding process S104, and the first removal process S105.

[0030] Figure 4(A) shows the state after the first silicon carbide polycrystalline films 400, 400a, etc. have been deposited on the first support substrates 100, 100a, etc., held in the substrate holder inside the deposition chamber 1001 of the deposition apparatus 1000, and Figure 4(B) shows the first support substrates 100, 100a and the first silicon carbide polycrystalline films 400, 400a after they have been removed from the deposition chamber 1001 and separated from the substrate holder.

[0031] The first film formation step S103 is a step performed after the first support substrate in-furnace placement step S102 in which a first silicon carbide polycrystalline film 400, 400a, etc. is formed on the target surface of the first support substrate 100, 100a, etc. by CVD. The first silicon carbide polycrystalline film 400 can be obtained by reacting a raw material gas such as a silicon-based raw material gas or a carbon-based raw material gas in the gas phase and depositing it on the target surface of the first support substrate 100.

[0032] As silicon-based raw material gases, for example, silane (SiH4) can be used, as well as chlorine-based silicon raw material-containing gases (chloride-based raw materials) that contain chlorine, which has etching properties, such as monochlorosilane (SiH3Cl), dichlorosilane (SiH2Cl2), trichlorosilane (SiHCl3), and tetrachlorosilane (SiCl4).

[0033] Furthermore, as carbon-based raw material gases, hydrocarbon gases such as methane (CH4), propane (C3H8), and acetylene (C2H2) can be used.

[0034] In addition to the above, gases containing both silicon and carbon, such as trichloromethylsilane (CH3Cl3Si), trichlorophenylsilane (C6H5Cl3Si), dichloromethylsilane (CH4Cl2Si), dichlorodimethylsilane ((CH3)2SiCl2), chlorotrimethylsilane ((CH3)3SiCl), and tetramethylsilane ((CH3)3SiH), can also be used as raw material gases.

[0035] As a specific example of the first film deposition process S103, first, the film deposition chamber 1001, in which multiple first support substrates 100 are arranged, is reduced in pressure. Next, an inert gas such as argon with an adjusted flow rate is introduced into the film deposition chamber 1001 while the temperature inside the film deposition chamber 1001 is raised to the reaction temperature of the raw material gas. The reason for introducing the inert gas is to create an inert atmosphere for the substrate so that no reaction that would inhibit film deposition occurs on the first support substrates 100 before film deposition. Once the temperature inside the film deposition chamber 1001 reaches the reaction temperature, the introduction of the inert gas is stopped, and raw material gases such as silicon-based gas and carbon-based gas, dopant gas, and carrier gas are introduced into the film deposition chamber 1001. Chemical reactions are carried out on the film deposition target surface of the first support substrates 100 and in the gas phase for a predetermined time under atmospheric pressure, so that silicon carbide nuclei are formed on the film deposition target surface, becoming amorphous or microcrystalline, and growing into a columnar crystalline structure. As a result, the first silicon carbide polycrystalline film 400 is formed on the film deposition target surface of the first support substrate 100.

[0036] The dopant gas is an impurity doping gas supplied simultaneously with the raw material gas in an amount corresponding to the target conductivity. For example, nitrogen (N2) gas can be used when the conductivity type is n-type, and trimethylaluminum (TMA) gas can be used when the conductivity type is p-type.

[0037] A carrier gas is a gas that can be used simultaneously with the raw material gas and dopant gas. A gas that can spread the raw material gas onto the film-forming surface without hindering the formation of the first silicon carbide polycrystalline film 400 can be used as the carrier gas. Examples of carrier gases include hydrogen (H2), which has excellent thermal conductivity and an etching effect on silicon carbide.

[0038] It is preferable to deposit the first silicon carbide polycrystalline film 400 to a thickness (deposited film thickness) of 600 μm to 1500 μm. With such a film thickness, the thickness of the silicon carbide single crystal substrate obtained after post-processing such as surface grinding and surface polishing can be adjusted to 350 μm to 500 μm. For example, if the thickness of the silicon carbide polycrystalline substrate to be mass-produced is to be 350 μm, the film thickness of the first silicon carbide polycrystalline film 400 can be set to 600 μm, taking into account that the thickness of the first silicon carbide polycrystalline film 400 will decrease due to surface grinding and surface polishing.

[0039] If the film thickness is too thick, the amount of silicon carbide to be ground and polished in subsequent processes will increase, and the amount of raw material gas and carrier gas used, as well as the film deposition time, may worsen manufacturing costs and productivity. Therefore, it is preferable to limit the upper limit of the film thickness to approximately 1500 μm.

[0040] When forming the first silicon carbide polycrystalline film 400, the film formation temperature is preferably, for example, 1200 to 1500°C, considering productivity, but is not limited to this.

[0041] In the first film formation step S103, the average film formation rate for forming the first silicon carbide polycrystalline film 400 is preferably 200 μm / hour or less, considering the stability of film formation. For example, the average film formation rate can be adjusted by controlling the growth rate of the growing first silicon carbide polycrystalline film 400 by changing the flow rate of the raw material gas, such as a silicon-based raw material gas or a carbon-based raw material gas.

[0042] The gas flow rate ratio is not particularly limited, but for example, in the case of a mixed gas using SiCl4 as the silicon-containing gas, CH4 as the carbon-containing gas, H2 as the carrier gas, and N2 as the impurity doping gas, the volume ratio of the mixed gas composition can be set to SiCl4:CH4:H2:N2 = 1:1:10:1~100.

[0043] Furthermore, processes related to the first film deposition process S103 include a filling process in which an inert gas such as argon is circulated into the film deposition chamber 1001 before film deposition, and a cooling process in which the raw material gas, doping gas, and carrier gas are stopped immediately after film deposition, and the inside of the film deposition chamber 1001 is cooled to room temperature.

[0044] (First grinding process S104) Figure 4(C) shows a cross-sectional view of the first silicon carbide polycrystalline film 400, 400a with its sides 401, 401a removed to expose the first support substrates 100, 100a. The first grinding step S104 is a step of grinding or polishing the sides 401, 401a of the first silicon carbide polycrystalline film 400, 400a until the sides of multiple first support substrates 100, 100a are exposed. Grinding and polishing can be performed using, for example, a machining center, cylindrical grinder, or surface grinder, but is not limited to these.

[0045] Furthermore, the first silicon carbide polycrystalline film is deposited not only on the first support substrate but also on the substrate holder that holds the first support substrate, and in some cases the first silicon carbide polycrystalline film is continuously deposited on both the first support substrate and the substrate holder. In this case, by separating the first support substrate and the substrate holder, a portion of the first support substrate that was covered by the first silicon carbide polycrystalline film is exposed. If this exposure allows the first removal step S105 described later to be performed, the first grinding step S104 can be omitted.

[0046] (First removal step S105) Figure 4(D) shows a cross-sectional view of the state after the first support substrates 100 and 100a have been removed from the first silicon carbide polycrystalline films 400 and 400a. The first removal step S105 is a step in which the first support substrates 100 and 100a are removed from the laminate consisting of the first support substrates 100 and 100a and the first silicon carbide polycrystalline films 400 and 400a, thereby separating the first silicon carbide polycrystalline films 400 and 400a.

[0047] If the first support substrates 100 and 100a are carbon substrates, they can be removed by burning them by heating them to, for example, about 1000°C in an atmospheric environment at normal pressure. For example, the laminate described above can be placed in the film deposition chamber 1001 and the temperature inside the film deposition chamber 1001 can be raised to burn the first support substrates 100 and 100a. Alternatively, the first support substrates 100 and 100a may be burned using a firing apparatus or the like prepared separately from the film deposition apparatus 1000.

[0048] If the first support substrates 100 and 100a are silicon substrates, instead of combustion removal by heating, the first support substrates 100 and 100a may be removed by dissolving them in a chemical solution. Alternatively, if the first support substrates 100 and 100a can be removed from the first silicon carbide polycrystalline films 400 and 400a by mechanical impact, that method may also be used.

[0049] Since the first silicon carbide polycrystalline film is deposited on both the front and back surfaces of the first support substrate, two first silicon carbide polycrystalline films can be obtained from one first support substrate after the first removal step S105. Specifically, first silicon carbide polycrystalline films 410 and 420 can be obtained from the first support substrate 100, and first silicon carbide polycrystalline films 410a and 420a can be obtained from the first support substrate 100a.

[0050] Furthermore, it is preferable to record information that allows for the identification of which first silicon carbide polycrystalline film was obtained from which surface of the first support substrate. This record can be used to determine the curvature of the front surface 701 and back surface 702 of the second support substrate 700, which will be described later.

[0051] <Adjustment Stage S200> The adjustment step S200 is a step in which the curvature of the film deposition surface of the second support substrate is adjusted based on the measurement results of the surface curvature of the first silicon carbide polycrystalline film 400 obtained in the prototyping step S100. The adjustment step S200 includes, for example, the following steps.

[0052] (First warpage measurement process S201) The first warpage measurement step S201 is a step in which the amount of warpage of the surface of the first silicon carbide polycrystalline films 410, 420, 410a, 420a, etc. is evaluated by directly measuring the amount of warpage of the surface of the first silicon carbide polycrystalline films 410, 420, 410a, 420a, etc. after the first removal step S105. The explanation of the first warpage measurement step S201 will be explained below using explanatory diagrams that supplement the explanation shown in Figure 5.

[0053] Figure 5(A) is a cross-sectional view of the first silicon carbide polycrystalline films 410 and 420, which are films deposited on the film deposition target surfaces (front surface 101, back surface 102) of the first support substrate 100 located at the first position 1100, and Figure 5(B) is a cross-sectional view of the first silicon carbide polycrystalline films 410a and 420a, which are films deposited on the film deposition target surfaces (front surface 101a, back surface 102a) of the first support substrate 100a located at the second position 1100a.

[0054] If, in the preceding step of this process, it is recorded that the films deposited on the film-deposition target surfaces (front surface 101, back surface 102) of the first support substrate 100 disposed at the first position 1100 are the first silicon carbide polycrystalline films 410 and 420, and similarly, it is recorded that the films deposited on the film-deposition target surfaces (front surface 101a, back surface 102a) of the first support substrate 100a disposed at the second position 1100a are the first silicon carbide polycrystalline films 410a and 420a, then in this step, it is preferable to record the measured values ​​of the warpage amounts 412, 422, 412a, and 422a (Figure 5(A), (B)) of the surfaces 411, 421, 411a, and 421a (Figure 5(A), (B)) of the first silicon carbide polycrystalline films 410, 420, 410a, and 420a, linked to these records.

[0055] Figure 5(C) shows an example of recording the measured values. For example, one recording method is to have a column on the far left for the first position 1100, the second position 1100a..., a column in the middle for the curvature amount of the film-forming surface of the first support substrate corresponding to the first position 1100, the second position 1100a..., and a column on the far right for the warpage amount of the first silicon carbide polycrystalline film corresponding to the curvature amount of the film-forming surface of the first support substrate ○○○○, △△△△....

[0056] Furthermore, if the curvature amounts of the front surface 101 and the back surface 102 of the first support substrate are different, or if the warpage amounts 412 and 422 of the front surfaces 411 and 421 of the first silicon carbide polycrystalline films 410 and 420 are different due to this difference in curvature, then these may be recorded separately.

[0057] Warpage refers to the difference in height of the curved surfaces that constitute a typical profile of the first silicon carbide polycrystalline film separated from the first support substrate, such as the front, back, or centerline. In this embodiment, the warpage of the surface of the first silicon carbide polycrystalline film can be determined by measuring the shape of the surface of the first silicon carbide polycrystalline film (for example, the opposite side of the first support substrate that does not face the surface to be deposited). For measuring the warpage, an optical measuring instrument such as a laser displacement meter can be used, and in addition, the warpage can be obtained using a contact-type measuring instrument.

[0058] (First curvature adjustment process S202) In the first curvature adjustment step S202, after the first warpage measurement step S201, the curvature of the film-forming surface of the second support substrate is adjusted based on the evaluated warpage. Specifically, for example, the following procedure can be used.

[0059] • Setting the curvature amount of the film deposition target surface of the second support substrate. Figure 6 is a scatter plot obtained by representing the amount of warpage of the surface of the first silicon carbide polycrystalline film as a point against the amount of curvature of the surface to be deposited on the first support substrate, and a graph showing the straight line of a linear function obtained by linear regression based on the scatter plot as a dotted line. In the graph, the X axis is the amount of curvature of the surface to be deposited on the first support substrate, X1, and the Y axis is the amount of warpage of the surface of the first silicon carbide polycrystalline film, Y1. In Figure 6, the amount of warpage of the surface of the first silicon carbide polycrystalline film was actually deposited using the first support substrate under predetermined conditions and plotted. Details of the deposition test of the first silicon carbide polycrystalline film will be described in <Specific Examples> below.

[0060] In Figure 6, a first silicon carbide polycrystalline film with a thickness of 1300 μm was deposited under condition A by varying the curvature of the surface to be deposited on the first support substrate, and the amount of curvature was plotted at four points marked with ●. Based on this plot, a linear function (Y1=aX1, where "a" is the slope of the line, i.e., a constant) is shown as a dotted line. The same applies to the plots marked with ◆, ▲, ○, ◇, and △.

[0061] Figure 6 shows the results of six different film deposition tests conducted by varying the film thickness of the first silicon carbide polycrystalline film based on conditions A to C. In all of the deposition tests, the slope a of the linear function, which is a constant, satisfies 0.75 ≤ a ≤ 0.90.

[0062] Based on the results of the prototype stage S100, in the manufacturing stage S300, a second support substrate is prepared and a second silicon carbide polycrystalline film is deposited. Therefore, using the linear function Y1=aX1, a target value for the surface curvature of the second silicon carbide polycrystalline film is set, and the curvature of the deposition surface of the second support substrate is calculated. Specifically, X2 is the curvature of the deposition surface of the second support substrate, and Y is the target value for the surface curvature of the second silicon carbide polycrystalline film. G2 Therefore, the equation of the linear function can be set as shown in equation 0 below.

[0063] [Formula 0] a=(Y1-Y G2 ) / (X1-X2)···(0)

[0064] In equation (0), the slope a is on the left side. If we move the term in equation (0) to the left side and set the left side to X2, we get equation (1).

[0065] [Formula 1] X2 = X1 - (Y1 - Y G2 ) / a···(1)

[0066] In other words, the linear function Y1 = aX1 is obtained from the scatter plot shown in Figure 6, and the target value Y of the surface curvature of the second silicon carbide polycrystalline film is obtained. G2 By setting this, the curvature amount X2 of the film deposition target surface of the second support substrate can be calculated.

[0067] The second silicon carbide polycrystalline film may be used for a silicon carbide bonding substrate after being processed into a silicon carbide polycrystalline substrate. In this case, the silicon carbide polycrystalline substrate is bonded to a silicon carbide single crystal substrate using a peeling technique by ablation of hydrogen atoms or the like. At this time, the silicon carbide polycrystalline substrate may be vacuum-sucked by a suction pad or the like and conveyed. However, if the warp of the silicon carbide polycrystalline substrate is large, air leaks and it cannot be vacuum-sucked by the suction pad, resulting in a conveyance error of the silicon carbide polycrystalline substrate and affecting the productivity of the silicon carbide bonding substrate. Further, this conveyance mode can be adopted not only in the scene of bonding with a silicon carbide single crystal but also in other processes of manufacturing the silicon carbide bonding substrate.

[0068] Therefore, at the stage of the second silicon carbide polycrystalline film, it is important that the film has a small amount of warp. The target value Y of the amount of warp on the surface of the second silicon carbide polycrystalline film G2 can be arbitrarily set. For example, considering the problem of conveyance error as described above, the target value Y of the amount of warp on the surface of the second silicon carbide polycrystalline film G2 may be set such that -100 μm ≤ Y G2 ≤ +100 μm. Here, when Y G2 is 0, the surface of the second silicon carbide polycrystalline film is flat without warping. Similarly, when Y G2 is +100 μm, the surface of the second silicon carbide polycrystalline film is warped convexly by 100 μm, and when Y G2 is -100 μm, the surface of the second silicon carbide polycrystalline film is warped concavely by 100 μm.

[0069] In FIG. 6, straight lines are drawn for the cases where Y1 is +100 μm and -100 μm, and Y G2X2 can be determined by setting the following. For example, in the case of the film deposition conditions plotted as ●, according to the linear function line (Y1=aX1) shown by the dotted line, when Y1 is +100μm, X2 is approximately +100μm as shown by the downward arrow, when Y1 is 0μm, X2 is approximately 0μm, and when Y1 is -100μm, X2 is approximately -135μm as shown by the upward arrow. In other words, for the film deposition conditions plotted as ●, X2 should be within the range of -135μm to +100μm, but if set to 0μm, even considering some manufacturing errors, Y G2 -100μm≦Y G2 It is considered that the condition ≤ +100 μm is sufficiently satisfied.

[0070] In the case of other film deposition conditions shown in Figure 6, the same procedure as described above can be followed for Y G2 -100μm ≤ Y G2 X2 can be calculated and set so as to sufficiently satisfy the condition ≤ +100 μm.

[0071] Furthermore, the optimal value for the warpage of the silicon carbide polycrystalline film cannot be determined definitively, as it varies depending on the film thickness during the deposition process, the amount of grinding during the polishing process, and the final substrate thickness and warpage specifications. Therefore, Y G2 -100μm ≤ Y G2 It is not limited to being ≤ +100 μm.

[0072] Furthermore, the scatter plots, linear functions based on them, and the values ​​of their slopes described above were derived based on the following specific examples, and the present invention is not limited to these. If the conditions necessary for the deposition of silicon carbide polycrystalline films, such as the configuration of the film deposition apparatus, raw material gas, and film deposition temperature, are changed, scatter plots and the like can be created based on the results obtained from the film deposition based on these changes to set the curvature amount of the second support substrate.

[0073] <Specific example> Ten graphite support substrates, each with a diameter of 170 mm and a flat surface (both front 101 and back 102) with a curvature of 0 μm, were used as the first support substrate 100. A silicon carbide polycrystalline film 400 was deposited using a film deposition apparatus 1000. The gas flow rate volume ratio conditions during film deposition were three conditions A, B, and C, pre-selected from the ratio SiCl4:CH4:H2:N2 = 1:1:10:1~100. The first silicon carbide polycrystalline film 400 was deposited so that its thickness was 600 μm to 1300 μm under conditions A, B, and C.

[0074] The film deposition was not performed on all 10 first support substrates 100 at once, but rather each of the 10 first support substrates 100 was placed at the first position 1100, and the film deposition was performed 10 times. In other words, the film deposition conditions were the same for all 10 first support substrates 100. It should be noted that during this film deposition process, the first support substrates may be placed at other positions to deposit the first silicon carbide polycrystalline film, and the linear function in that case may also be derived in a similar manner. It is expected that the same or different results will be obtained at positions other than the first position 1100.

[0075] Subsequently, the outer periphery of the first silicon carbide polycrystalline film 400 was ground down to a diameter of 6 inches to expose the side surface of the first support substrate 100. The first support substrate 100 was then burned off, and a total of 20 first silicon carbide polycrystalline films 410 and 420 with a diameter of 6 inches were obtained. The warpage of their surfaces was measured and the average value was calculated.

[0076] As a result of the experiments conducted so far, the curvature X1 of the film deposition target surface of the first support substrate 100 was 0 μm, and the surface warpage Y1 of the first silicon carbide polycrystalline film 400 was 30 μm (see the ● plot in Figure 6).

[0077] Next, the curvature of the surface to be deposited on the first support substrate 100 was changed, and the first silicon carbide polycrystalline film 400 was deposited in the same manner as above under the deposition conditions of condition A, with a thickness of 1300 μm. The surface warpage was measured and its average value was calculated. In Figure 6, four points marked with ● are plotted as test results. Based on this plot, a linear function line (Y1=aX1) is shown as a dotted line in Figure 6.

[0078] In the same manner as the above test "Condition A, film thickness 1300 μm", tests were conducted for "Condition A, film thickness 1000 μm", "Condition A, film thickness 800 μm", "Condition A, film thickness 600 μm", "Condition B, film thickness 800 μm", and "Condition C, film thickness 800 μm". Similarly, the average value of the surface warpage of the first silicon carbide polycrystalline film 400 was calculated and plotted in Figure 6 (see ◆, ▲, ○, ◇, △ in Figure 6), and the linear function line (Y1=aX1) is shown as a dotted line in Figure 6.

[0079] These tests allowed us to conduct experiments to confirm the warpage of the first silicon carbide polycrystalline film 400 by varying the film thickness in the range of 600 μm to 1300 μm under the same condition A, and experiments to confirm the warpage of the first silicon carbide polycrystalline film 400 by changing the condition from A to B and then to C, in which the film thickness was 800 μm in each case.

[0080] As shown in Figure 6, for all linear functions (Y1=aX1), the slope a satisfies the condition 0.75 ≤ a ≤ 0.90.

[0081] • Curving of the film deposition target surface of the second support substrate After performing the "setting the curvature amount of the film-deposition target surface of the second support substrate" described above, the film-deposition target surface of the second support substrate to be used in the manufacturing stage S300 described later is curved so that it matches the curvature amount X2 set based on this setting. It is important that the second support substrate is exactly the same as the first support substrate 100 except for the curved shape of the film-deposition target surface. Therefore, the second support substrate is prepared by curving it so that it is made of the same material as the first support substrate 100 and has the same shape except for the film-deposition target surface. Specifically, the material for the second support substrate is selected as follows, and the curvature amount is checked and managed by performing grinding, polishing, etc., on the film-deposition target surface while controlling the curvature amount.

[0082] As the material to be processed, the support substrate for the silicon carbide polycrystalline film is confirmed to be free of defects such as scratches, and the same number of disc-shaped thin films as the first support substrate 100 are selected. For example, similar to the first support substrate 100, disc-shaped silicon substrates or graphite substrates with a thickness of 0.05 mm to 5.0 mm and a diameter of 4 inches to 10 inches (preferably 6 to 10 inches in diameter, more preferably 8 to 10 inches in diameter) can be used.

[0083] As the second support substrate, one may purchase and use a substrate whose film deposition surface has a curvature amount X2, but for example, a graphite disc with a thickness of 300 μm to 10 mm cut in parallel may also be used as the material for creating the second support substrate.

[0084] The surface to be coated and the thickness of the second support substrate can be adjusted by grinding or polishing. For example, to adjust the second support substrate to a predetermined thickness, surface grinding can be performed using a surface grinder or the like. As for polishing, for example, the surface to be coated can be lapped with a diamond slurry, hard polished with a mixed slurry of diamond and alumina, and then polished with a silica slurry (colloidal silica, pH 11) to curve the surface to be coated and finish it as the second support substrate.

[0085] For measuring the curvature of the surface to be coated, for example, an electron microscope or a precision shape measuring instrument using laser measurement can be used.

[0086] Furthermore, it is preferable to record the curvature of the surface to be film-deposited on the second support substrate before depositing the second silicon carbide polycrystalline film.

[0087] Figure 7 shows a schematic perspective view of the second support substrate. The second support substrate 700 has a surface 701, a back surface 702, and a side surface 703. A second silicon carbide polycrystalline film is deposited on the surface 701 and back surface 702, which are the surfaces to be coated, by CVD. Although the side surface 703 is not intended for coating, the coating is also deposited on the side surface 703 by performing the coating treatment on the surface 701 and back surface 702.

[0088] The second support substrate 700 is a substrate that is to be placed in the deposition chamber 1001 at the first position 1100, which is the same position as the first support substrate 100. Similarly, the second support substrate 700a is a substrate that is to be placed at the a position 1100a. The second support substrate 700a also has a front surface 701a, a back surface 702a, and a side surface 703a. Figure 7 shows, as an example, the second support substrates 700 and 700a, which have different curvatures of the deposition target surface due to the difference in the amount of warping of the first silicon carbide polycrystalline film at the first position 1100 and the a position 1100a.

[0089] Furthermore, at positions other than the first position 1100 and the a-position 1100a, a second support substrate can be prepared in which the curvature of the surface to be deposited is set according to the amount of warpage of the first silicon carbide polycrystalline film deposited at that position.

[0090] <Manufacturing stage S300> In manufacturing step S300, silicon carbide is deposited on a second support substrate having a film deposition surface with adjusted curvature to obtain a second silicon carbide polycrystalline film with reduced surface warping. Manufacturing step S300 includes, for example, the following steps.

[0091] (Second support board preparation step S301) The second support substrate preparation step S301 is a step in which the second support substrate 700 is prepared. Specifically, it is confirmed that there are no defects such as scratches on the support substrate for the silicon carbide polycrystalline film, and one or more second support substrates are selected. If this step overlaps with the above-mentioned "curving of the film deposition surface of the second support substrate", the overlapping part may be omitted. Also, if the second support substrate 700 is obtained by purchase or other means, this step may be used to confirm whether the curvature of the film deposition surface is appropriate.

[0092] (Second support substrate placement process in furnace S302) The second support substrate in-furnace placement process S302 is a process of placing the second support substrates 700, 700a, etc. (sometimes referred to collectively as "second support substrate 700") in the deposition chamber 1001 of the deposition apparatus 1000. This process is the same as the first support substrate in-furnace placement process S102, except that the second support substrate 700 is used instead of the first support substrate 100.

[0093] Only one second support substrate 700 may be placed in the deposition chamber 1001, or multiple second support substrates 700 may be placed. Figure 8 is a schematic diagram of the deposition apparatus with the second support substrates placed in the deposition chamber. Multiple second support substrates 700 can be placed inside the deposition chamber 1001 by holding them in substrate holders (not shown). In Figure 8, the arrangement of multiple second support substrates in the lateral direction is represented by the second support substrate 700 at the far left, the second support substrate 700a placed a position from the left, the space between the second support substrate 700 and the second support substrate 700a, and the space between the second support substrate 700a and the temperature control device 1006, indicated by "...". Furthermore, the position in the substrate holder where the second support substrate 700 is placed is the first position 1100, and the position a from the left where the second support substrate 700a is placed is the a position 1100a.

[0094] An example of the second support substrate placement process S302 is to first place one or more second support substrates, within the number that can be accommodated in the substrate holder, and then place the substrate holder together with the placed second support substrates into the deposition chamber 1001. When multiple second support substrates are placed, it is preferable to place the second support substrates in a row at equal intervals such that the surfaces to be deposited are parallel and the centers of the substrates are on the same straight line, in order to improve the unevenness of the silicon carbide polycrystalline film deposition and make the film thickness as uniform as possible.

[0095] Furthermore, it is preferable to pre-record necessary information such as predetermined positions (for example, the first position 1100 and the a-position 1100a) for arranging the second support substrate within the film deposition chamber 1001, and the amount of curvature of the film deposition target surface of each second support substrate.

[0096] (Second film formation step S303) The second film deposition step S303 is a step in which a silicon carbide polycrystalline film is deposited, similar to the first film deposition step S103, and is the same as the first film deposition step S103 except that the second support substrate 700 is used instead of the first support substrate 100.

[0097] Figure 9 is a schematic cross-sectional view of the second silicon carbide polycrystalline film 800 during the second film formation process S303, the second grinding process S304, and the second removal process S305.

[0098] Figure 9(A) shows the state after the second silicon carbide polycrystalline films 800, 800a, etc. have been deposited on the second support substrates 700, 700a, etc., held in the substrate holder inside the deposition chamber 1001 of the deposition apparatus 1000, and Figure 9(B) shows the second support substrates 700, 700a and the second silicon carbide polycrystalline films 800, 800a after they have been removed from the deposition chamber 1001 and separated from the substrate holder.

[0099] The second film formation step S303 is a step performed after the second support substrate in-furnace placement step S202 in which a second silicon carbide polycrystalline film 800, 800a, etc. is formed on the target surface of the second support substrate 700, 700a, etc. by CVD. The second silicon carbide polycrystalline film 800 can be obtained in the same manner as in the first film formation step S103 by reacting a raw material gas such as a silicon-based raw material gas or a carbon-based raw material gas in the gas phase and depositing it on the target surface of the second support substrate 700. The film thickness of the second silicon carbide polycrystalline film 800 can be adjusted so that it is the same as the film thickness of the first silicon carbide polycrystalline film 400 by adjusting the film formation time.

[0100] In the method for producing a silicon carbide polycrystalline film of the present invention, it is important to carry out the second film deposition step S303, but other steps are not essential. For example, the "prototype stage S100" and the "adjustment stage S200" may be carried out by the present invention, or they may be outsourced, and the second film deposition step may be carried out based on the results of the outsourcing. Similarly, steps other than the second film deposition step S303 in the "manufacturing stage S300" may also be carried out by the present invention, or they may be outsourced.

[0101] (Second grinding process S304) The second grinding step S304, similar to the first grinding step S104, is a step in which the sides 801 and 801a of the second silicon carbide polycrystalline film 800 and 800a are removed to expose the second support substrate 700 and 700a, as shown in Figure 9(C). Grinding and polishing can be carried out using, for example, a machining center, cylindrical grinding machine, or surface grinding machine, but is not limited to these.

[0102] Furthermore, the second silicon carbide polycrystalline film is deposited not only on the second support substrate but also on the substrate holder that holds the second support substrate, and in some cases the second silicon carbide polycrystalline film is continuously deposited on both the second support substrate and the substrate holder. In this case, by separating the second support substrate and the substrate holder, a portion of the second support substrate that was covered by the second silicon carbide polycrystalline film is exposed. If this exposure allows the second removal step S305 described later to be performed, the second grinding step S304 can be omitted.

[0103] (Second removal step S305) Figure 9(D) shows a cross-sectional view of the state after the second support substrates 700, 700a have been removed from the second silicon carbide polycrystalline films 800, 800a. Similar to the first removal step S105, the second removal step S305 is a step in which the second support substrates 700, 700a are removed from the laminate consisting of the second support substrates 700, 700a and the second silicon carbide polycrystalline films 800, 800a, thereby separating the second silicon carbide polycrystalline films 800, 800a.

[0104] If the second support substrates 700 and 700a are carbon substrates, they can be removed by combustion by heating them to, for example, about 1000°C in an atmospheric atmosphere at normal pressure. If the second support substrates 700 and 700a are silicon substrates, instead of combustion removal by heating, they may be removed by dissolving them in a chemical solution. Alternatively, if the second support substrates 700 and 700a can be removed from the second silicon carbide polycrystalline film 800 and 800a by mechanical impact, that method may also be used.

[0105] Since the second silicon carbide polycrystalline film is deposited on the front and back surfaces of the second support substrate, which are the target surfaces for film deposition, two second silicon carbide polycrystalline films can be obtained from one second support substrate after the second removal step S305. Specifically, second silicon carbide polycrystalline films 410 and 420 can be obtained from the second support substrate 700, and second silicon carbide polycrystalline films 810a and 820a can be obtained from the second support substrate 700a.

[0106] Furthermore, it is preferable to record information that allows for the identification of which second silicon carbide polycrystalline film was obtained from which target surface of the second support substrate. Alternatively, the amount of surface warpage of the second silicon carbide polycrystalline film may be measured and confirmed to be within an acceptable range, and this may also be recorded.

[0107] Once it is confirmed that the amount of warping on the surface of the second silicon carbide polycrystalline film has been sufficiently reduced, the second silicon carbide polycrystalline film can be mass-produced by repeating the procedure of "bending the film deposition target surface of the second support substrate" and the manufacturing step S300.

[0108] The obtained second silicon carbide polycrystalline film may be used to manufacture a silicon carbide polycrystalline substrate by polishing or other processes as needed. In this case, a polishing step may be included to smooth the surface of the silicon carbide polycrystalline film in order to ensure the surface accuracy required for use in semiconductor manufacturing processes. For example, the silicon carbide polycrystalline film may be lapped with a diamond slurry, hard polished with a mixed slurry of diamond and alumina, and then polished with a silica slurry (colloidal silica, pH 11) to smooth the surface of the silicon carbide polycrystalline substrate.

[0109] [Method for evaluating the amount of warpage of polycrystalline silicon carbide films] Next, an example of a method for evaluating the amount of warpage of the silicon carbide polycrystalline film of the present invention will be described. For example, as described above, the second silicon carbide polycrystalline film can be mass-produced by repeating the procedure of "bending the surface to be deposited on the second support substrate" and the procedure of <manufacturing step S300>. However, even if the same deposition conditions are set, over time, silicon carbide may precipitate on the deposition chamber 1001 and the substrate holder, etc., causing changes in the environment inside the deposition chamber 1001, which may result in large variations in the amount of warpage of the surface of the obtained second silicon carbide polycrystalline film. In such cases, the same procedure as <adjustment step S200> is performed to adjust the amount of warpage of the surface to be deposited on the support substrate used thereafter based on the measurement of the amount of warpage of the surface of the second silicon carbide polycrystalline film, and then the same procedure as <manufacturing step S300> is performed to deposit the silicon carbide polycrystalline film, thereby reducing the variation in the amount of warpage of the surface of the obtained silicon carbide polycrystalline film.

[0110] Furthermore, even when a new support substrate with a changed coefficient of thermal expansion is used as the second support substrate, or when conditions are changed in each process that may affect the amount of warping of the silicon carbide polycrystalline film, such as changing the components in the film deposition chamber 1001 of the film deposition apparatus 1000 or the shape of the substrate holder, the variation in the amount of warping of the surface of the obtained silicon carbide polycrystalline film can be reduced by performing the same procedure as in <adjustment stage S200> and <manufacturing stage S300>.

[0111] Furthermore, even if the amount of warpage of the second silicon carbide polycrystalline film is within the acceptable range, the same procedures as in <Adjustment Stage S200> and <Manufacturing Stage S300> may be performed to further reduce the variation in the amount of warpage. An example of a method for evaluating the amount of warpage of the silicon carbide polycrystalline film is the following process.

[0112] (Second warpage measurement process) In the second warpage measurement step, the amount of warpage of the surface of the second silicon carbide polycrystalline films 810, 820, 810a, 820a, etc. is measured. The explanation of the second warpage measurement step, as shown in Figure 10, will be further explained using supplementary diagrams.

[0113] Figure 10(A) is a cross-sectional view of the second silicon carbide polycrystalline films 810 and 820, which are films deposited on the film deposition target surface of the second support substrate 700 located at the first position 1100, and Figure 10(B) is a cross-sectional view of the second silicon carbide polycrystalline films 810a and 820a, which are films deposited on the film deposition target surface of the second support substrate 700a located at the second position 1100a.

[0114] The fact that the film deposited on the film-deposition target surface of the second support substrate 700 disposed at the first position 1100 is the second silicon carbide polycrystalline film 810, 820 can be recorded in the step prior to this process, and similarly, the fact that the film deposited on the film-deposition target surface of the second support substrate 700a disposed at the second position 1100a is the second silicon carbide polycrystalline film 810a, 820a can be recorded.

[0115] Figure 10(C) shows an example of recording the measured values. For example, one recording method is to have a column on the far left for the first position 1100, the second position 1100a..., a column in the middle for the curvature of the film-forming surface of the second support substrate corresponding to the first position 1100, the second position 1100a... ●●●●, ▲▲▲▲..., and a column on the far right for the surface warpage of the second silicon carbide polycrystalline film corresponding to the curvature of the film-forming surface of the second support substrate ●●●●, ▲▲▲▲... ■■■■, ◆◆◆◆.....

[0116] Furthermore, if the curvature amounts of the front surface 701 and the back surface 702 of the second support substrate are different, or if the warpage amounts 812 and 822 of the front surfaces 811 and 821 of the second silicon carbide polycrystalline films 810 and 820 are different due to this difference in curvature, then these may be recorded separately.

[0117] Warpage refers to the difference in height of the curved surfaces that constitute a typical profile of the second silicon carbide polycrystalline film separated from the second support substrate, such as the front, back, or centerline. In this embodiment, the warpage of the surface of the second silicon carbide polycrystalline film can be determined by measuring the shape of the surface of the second silicon carbide polycrystalline film (for example, the opposite side of the second support substrate that does not face the film deposition surface). For measuring the warpage, an optical measuring instrument such as a laser displacement meter can be used, and in addition, the warpage can be obtained using a contact-type measuring instrument.

[0118] (Second curvature adjustment process) In the second curvature adjustment step, the curvature of the film-deposition surface of the third support substrate, which will be used as a new support substrate after the second warp measurement step, is adjusted. Specifically, the procedure is the same as in the "first curvature adjustment step S202," by setting the curvature of the film-deposition surface of the third support substrate and performing the curvature processing of the film-deposition surface of the third support substrate.

[0119] For example, the amount of curvature of the film-deposition target surface of the third support substrate can be determined by preparing a scatter plot obtained by representing the amount of warpage of the surface of the second silicon carbide polycrystalline film as a point, in the same way as in Figure 6, and finding a linear function line.

[0120] Specifically, X2 is the curvature of the film deposition surface of the second support substrate, X3 is the curvature of the film deposition surface of the third support substrate, Y2 is the surface warp of the second silicon carbide polycrystalline film, and Y is the target value for the surface warp of the third silicon carbide polycrystalline film. G3 In this case, the curvature amount X3 of the film deposition target surface of the third support substrate can be adjusted to the curvature amount calculated by the following equation 2.

[0121] [Formula 2] X3 = X2 - (Y2 - Y G3 ) / b···(2)

[0122] In Equation 2, b is the slope of a linear function (Y2=bX2) obtained by linear regression based on a scatter plot obtained by representing the amount of warpage of the surface of the second silicon carbide polycrystalline film as a point with respect to the amount of curvature of the surface to be deposited on the second support substrate, with the X axis being X2 and the Y axis being Y2.

[0123] In Equation 2, for example, b satisfies 0.75 ≤ b ≤ 0.90.

[0124] Also, Y G3 For example, -100 μm ≤ Y G3 It can be set to satisfy the condition ≤ +100 μm.

[0125] (Third film formation process) In the third film deposition step, after the second curvature adjustment step, a third silicon carbide polycrystalline film with adjusted surface curvature is deposited on the target surface of the third support substrate. The silicon carbide polycrystalline film can be deposited in the same manner as in the second film deposition step S303, and the same process as in the second film deposition step S303 can be adopted, except that the third support substrate is used instead of the second support substrate 700.

[0126] (Third warpage measurement process) In the third warpage measurement step, the amount of warpage on the surface of the third silicon carbide polycrystalline film is measured after the third film formation step and the removal of the third support substrate. The specific procedure can be carried out by referring to and imitating the "first warpage measurement step" and "second warpage measurement step" described above, as well as Figures 5 and 6.

[0127] (Other processes) The method for producing a silicon carbide polycrystalline film of the present invention may include steps other than those described above. For example, these steps include: placing a third support substrate in the film deposition chamber (support substrate furnace placement step); grinding the side surface of the third silicon carbide polycrystalline film deposited on the third support substrate to expose the third support substrate (grinding step); and removing the third support substrate after the grinding step (removal step).

[0128] In the method for producing a silicon carbide polycrystalline film of the present invention, it is important to perform the second warpage measurement step, the second curvature adjustment step, and the third film formation step, but other steps are not essential. These other steps may be performed by the present invention, or they may be outsourced, and the second warpage measurement step, the second curvature adjustment step, and the third film formation step may be performed based on the results of the outsourcing.

[0129] <Variation> Hereinafter, the embodiment will be described in more detail, including modifications that differ from the example of the embodiment described above.

[0130] One example of the above embodiment involves recording the curvature of the film-forming surface of the first support substrate and the warp of the surface of the first silicon carbide polycrystalline film for each predetermined position (first position, position a, etc.) where the support substrate is arranged. Based on this recording, the curvature of the film-forming surface of the second support substrate is adjusted for each position, thereby improving the warp of the surface of the second silicon carbide polycrystalline film formed on the second support substrate. In other words, this embodiment reduces the warp of the silicon carbide polycrystalline film formed on each film-forming surface of the support substrate.

[0131] As a variation, an embodiment is described below in which a plurality of first support substrates, arranged in the deposition chamber by a substrate holder, are divided into multiple groups by dividing them into predetermined areas within the deposition chamber, and for each group, the average value of the curvature of the deposition target surface of the first support substrate and the average value of the surface warp of the first silicon carbide polycrystalline film are recorded, and based on these records, the curvature of the second support substrate is adjusted collectively for each group, thereby reducing the surface warp of the second silicon carbide polycrystalline film deposited on the second support substrate collectively.

[0132] Figure 11 shows the arrangement of the first support substrate in the film deposition chamber in a modified embodiment (Figure 11(A)) and a schematic diagram showing the amount of surface warpage of the first silicon carbide polycrystalline film deposited on the film deposition target surface of the first support substrate in that arrangement (Figure 11(B)).

[0133] The arrangement shown in Figure 11(A) is the same as the arrangement of the first support substrate 100 shown in Figure 3. The arrangement of multiple first support substrates arranged laterally is represented by the side views of the multiple first support substrates 100 and the "..." written between them. The first support substrates 100 are arranged in rows at equal intervals so that their respective film deposition surfaces are parallel and the centers of each substrate are on the same straight line, for a total of 36 substrates. The curvature of the film deposition surface of each first support substrate 100 was set to 100 μm.

[0134] After arranging the 36 support substrates 100 as shown in Figure 11(A), a film deposition process was carried out to deposit a silicon carbide polycrystalline film onto the support substrates 100. As a result, the amount of curvature of the first silicon carbide polycrystalline film deposited on the nine first support substrates from the left end and the nine first support substrates from the right end of the deposition chamber was symmetrical and took on a gentle mountain shape, as shown in Figure 11(B). Therefore, the region in which these 18 first support substrates were arranged was designated as the first group.

[0135] Similarly, the curvature of the first silicon carbide polycrystalline films deposited on the first support substrates—three from the leftmost group toward the center and three from the rightmost group toward the center—was symmetrical, as shown in Figure 11(B), and took on a sloping shape where the film thickness decreased toward the center. Therefore, the region where these six first support substrates were arranged was designated as the second group.

[0136] Similarly, the curvature of the first silicon carbide polycrystalline film deposited on the 12 first support substrates in the central region sandwiched between the second group on both sides was symmetrical on both sides, as shown in Figure 11(B), and took the shape of a valley where the film thickness gradually decreased toward the center. Therefore, the region in which these 12 first support substrates were arranged was designated as the third group.

[0137] Compared to the average surface curvature of the first silicon carbide polycrystalline film in the first group, the average surface curvature of the first silicon carbide polycrystalline film in the second group was 100 μm smaller, indicating that the film was concave. Furthermore, compared to the average surface curvature of the first silicon carbide polycrystalline film in the first group, the average surface curvature of the first silicon carbide polycrystalline film in the third group was 200 μm smaller, indicating that the film was concave.

[0138] In this way, regions showing similar behavior in the curvature of the silicon carbide polycrystalline film surface were set as one group, and the average curvature for each group was calculated. Next, the curvature of the film-depositing surface of the second support substrate was set for each group collectively. The curvature of the film-depositing surface of the second support substrate can be set in the same manner as in the above embodiment. The results of the curvature obtained by film deposition carried out by changing the film deposition conditions are made into a scatter plot, and a linear function equation and its slope are derived from the scatter plot to set the target value of the curvature of the surface of the second silicon carbide polycrystalline film. Then, the curvature of the film-depositing surface of the second support substrate can be set using equations similar to those in equations 1 and 2.

[0139] When the target value for the surface curvature of the second silicon carbide polycrystalline film was set to 0 μm, the curvature of the film-forming surface of the second support substrate was calculated. The curvature of the film-forming surface of the second support substrate was 0 μm in the first group, +300 μm in the second group, and +400 μm in the third group. Therefore, the curvature of all 18 second support substrates in the first group was set to 0 μm, the curvature of all 6 substrates in the second group was similarly set to +300 μm, and the curvature of all 12 substrates in the third group was set to +400 μm, and the film-forming test was carried out in the same manner as above. As a result, the curvature of the 72 second silicon carbide polycrystalline films obtained from a total of 36 second support substrates was within the range of ±100 μm.

[0140] In the above modified example, we showed an example where the data was divided into three groups, but this is not the only way to do so, and the groups can be further subdivided. Also, if the curvature of all the silicon carbide polycrystalline films deposited simultaneously tends to be similar, there is no need to divide them into groups, and the curvature of the surface to be deposited on the second support substrate, which is deposited simultaneously, can be set uniformly.

[0141] As shown in this modified example, when similar tendencies are observed in the amount of warpage of silicon carbide polycrystalline films, they can be grouped together and the amount of curvature of the film-forming surface of the support substrate can be set collectively to reduce the amount of warpage of the silicon carbide polycrystalline films. In this case, the effort of adjusting the amount of curvature for each support substrate is eliminated, and the management of records such as curvature and warpage is simplified, thereby further improving the productivity of silicon carbide polycrystalline films. Based on this modified example, the method for manufacturing silicon carbide polycrystalline films of the present invention can be implemented.

[0142] Another modification involves focusing on the gas introduced into the deposition chamber 1001 to evaluate the amount of warping on the surface of the silicon carbide polycrystalline film, and adjusting the amount of curvature of the deposition target surface of the second support substrate based on the evaluated amount of warping. For example, the flow of raw material gas, carrier gas, dopant gas, etc., in the deposition chamber 1001 can be analyzed, and the results can be used. In this case, the tendency of how the amount of warping on the surface of the second silicon carbide polycrystalline film changes with changes in gas conditions, the thickness of the deposited second silicon carbide polycrystalline film, and conditions such as temperature before, during, and after deposition can be investigated and evaluated in advance, and the amount of curvature of the deposition target surface of the second support substrate can be adjusted based on the results of this evaluation to reduce the amount of warping on the surface of the second silicon carbide polycrystalline film. Based on this modification, the method for manufacturing a silicon carbide polycrystalline film of the present invention can be carried out.

[0143] Another modification is to evaluate the amount of curvature of the surface of the first silicon carbide polycrystalline film deposited inside the deposition chamber 1001, based on the arrangement of structures inside the deposition chamber 1001, according to the location within the chamber. For example, if there are locations where the flow of raw material gas, carrier gas, or dopant gas may be obstructed by structures inside the deposition chamber 1001, these locations should be evaluated as positions where the curvature of the deposition target surface of the second support substrate is set to be large. Even with such modifications, the above-described effects of this embodiment can be achieved in the same way, and the method for manufacturing a silicon carbide polycrystalline film of the present invention can be carried out.

[0144] Although several embodiments have been described above, each embodiment described is presented as an example and is not intended to limit the scope of the present invention. Each embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in at least one of the scope, spirit, and claims of the present invention and its equivalents.

[0145] According to each embodiment and its modified form, the productivity of silicon carbide polycrystalline films can be improved by including an evaluation step of evaluating a first curvature of the surface of a first silicon carbide polycrystalline film obtained by depositing it on a first film-deposition target surface of a first support substrate having a first film-deposition target surface whose curvature has been confirmed in advance, and a second film-deposition step of depositing a second silicon carbide polycrystalline film on a second film-deposition target surface of a second support substrate having a second film-deposition target surface whose curvature has been adjusted based on the evaluated first curvature. [Explanation of symbols]

[0146] 100: First support substrate, 100a: First support substrate, 101: Front surface, 102: Back surface, 103: Side surface, 400: First silicon carbide polycrystalline film, 400a: First silicon carbide polycrystalline film, 401: Side surface, 401a: Side surface, 410: First silicon carbide polycrystalline film, 410a: First silicon carbide polycrystalline film, 411: Front surface, 411a: Front surface, 412: Amount of warpage, 412a: Amount of warpage, 420: First silicon carbide polycrystalline film, 420a: First silicon carbide polycrystalline film, 421: Front surface, 421a: Front surface, 422: Amount of warpage, 422a: Amount of warpage, 700: Second support substrate, 700a: Second support substrate, 701: Front surface, 701a: Front surface, 702: Back surface, 702a: Back surface, 703: Side surface, 703a: Side surface, 800: Second silicon carbide polycrystalline film, 800a: Second silicon carbide polycrystalline film, 801: Side surface, 801a: Side surface, 810a: Second silicon carbide polycrystalline film, 811: Front surface, 812: Curvature, 820a: Second silicon carbide polycrystalline film, 821: Front surface, 822: Curvature, 1000: Film deposition apparatus, 1001: Film deposition chamber, 1002: Gas supply pipe, 1003: Gas supply volume control valve, 1004: Gas exhaust pipe, 1005: Gas exhaust volume control valve, 1006: Temperature control device, 1100: First position, 1100a: Position a

Claims

1. Based on the amount of curvature of the surface of the first silicon carbide polycrystalline film obtained by depositing a film on the film-depositing surface of a first support substrate having a film-depositing surface whose curvature has been confirmed in advance, at a predetermined position in the film-depositing apparatus, A second support substrate having a film deposition surface with an adjusted curvature, The process includes a second film formation step in which a second silicon carbide polycrystalline film is formed at the aforementioned location. A method for producing a silicon carbide polycrystalline film.

2. The amount of curvature of the film-forming surface of the second support substrate is adjusted based on the position of the internal structure of the film-forming apparatus. A method for producing a silicon carbide polycrystalline film according to claim 1.

3. The curvature of the film-forming surface of the first support substrate is X １ The curvature of the film-forming surface of the second support substrate is X ２ Y is the amount of curvature of the surface of the first silicon carbide polycrystalline film. １ The target value of the surface curvature of the second silicon carbide polycrystalline film is Y Ｇ２ When a is a constant, Curvature X of the film deposition surface of the second support substrate ２ The curvature is adjusted to the amount calculated by the following formula 1. A method for producing a silicon carbide polycrystalline film according to claim 1. [Formula 1] X ２ =X １ —(Y １ -Y Ｇ２ ) / a・・・(1)

4. A method for producing a silicon carbide polycrystalline film according to claim 3, wherein a satisfies 0.75 ≤ a ≤ 0.

90.

5. A first film formation step of forming a first silicon carbide polycrystalline film on the film formation target surface of the first support substrate, After the first film formation step, a first removal step is performed to remove the first support substrate from the first silicon carbide polycrystalline film, After the first removal step, a first warpage measurement step is performed to measure the amount of warpage on the surface of the first silicon carbide polycrystalline film, After the first warpage measurement step, a first curvature adjustment step is performed to adjust the curvature of the film-forming surface of the second support substrate, A method for producing a silicon carbide polycrystalline film according to claim 1, comprising a second removal step of removing the second support substrate from the second silicon carbide polycrystalline film after the second film formation step.

6. The second film formation step is, The first support substrate is arranged at a plurality of different positions, and the curvature of the film-forming surface of the second support substrate is adjusted accordingly. A plurality of the second support substrates, each having a different curvature of the film-forming surface of the second support substrate, are arranged at the aforementioned positions. A method for producing a silicon carbide polycrystalline film according to claim 1.

7. The curvature of at least one of the film-forming surfaces of the multiple second support substrates is different from the curvature of the film-forming surfaces of the other second support substrates. A method for producing a silicon carbide polycrystalline film according to claim 5.

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