Method for producing polycrystalline silicon carbide film

Abstract

A method for producing a polycrystalline silicon carbide film is provided with which the efficiency of producing a polycrystalline silicon carbide film can be improved.　The method for producing a polycrystalline silicon carbide film includes a second film deposition step, in which a second polycrystalline silicon carbide film is deposited, in a predetermined position in a film deposition device, on a second supporting substrate that has a film deposition surface having an amount of curvature regulated on the basis of the amount of surface warpage of a first polycrystalline silicon carbide film, the first polycrystalline silicon carbide film being obtained by film deposition, in the predetermined position, on a film deposition surface of a first supporting substrate, said film deposition surface having the amount of curvature thereof determined in advance.

Description

Method for manufacturing a silicon carbide polycrystalline film

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

[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.

[0003] Japanese Patent Publication No. 10-251062 Japanese Patent Publication No. 2021-116465

[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.

[0006] To solve the above problems, the present invention provides a method for manufacturing a silicon carbide polycrystalline film, which includes 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 on a first support substrate having a film formation surface whose curvature has been confirmed in advance, at a predetermined position in a film formation apparatus.

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

[0008] This is a flow diagram of a method for manufacturing a silicon carbide polycrystalline film according to an embodiment. This is a schematic perspective view of the first support substrate. This is a schematic diagram of a film deposition apparatus with the first support substrate arranged in the film deposition chamber. This is a schematic cross-sectional view showing the state after the first silicon carbide polycrystalline film has been deposited on the first support substrate held in a substrate holder in the film deposition chamber of the film deposition apparatus. This is a schematic cross-sectional view showing the first support substrate and the first silicon carbide polycrystalline film after they have been removed from the film deposition chamber and separated from the substrate holder. This is a schematic cross-sectional view showing the state in which the side surface of the first silicon carbide polycrystalline film has been removed to expose the first support substrate. This is a schematic cross-sectional view showing the state in which the first support substrate has been removed from the first silicon carbide polycrystalline film. This is a cross-sectional view of the first silicon carbide polycrystalline film, which is a film deposited on the film deposition target surface (front and back) of the first support substrate arranged in the first position. This is a cross-sectional view of the first silicon carbide polycrystalline film, which is a film deposited on the film deposition target surface (front and back) of the first support substrate arranged in the second position. This is an example of recording measured values. This is a scatter plot obtained by representing the amount of curvature 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 further, a graph showing the straight line of a linear function obtained by linear regression based on the scatter plot as a dotted line. This is a schematic perspective view of the second support substrate. This is a schematic perspective view of the second support substrate. This is a schematic diagram of the film deposition apparatus with the second support substrate placed in the film deposition chamber. This is a schematic cross-sectional view showing the state after the second silicon carbide polycrystalline film has been deposited on the second support substrate held in the substrate holder in the film deposition chamber of the film deposition apparatus. This is a schematic cross-sectional view of the second support substrate and the second silicon carbide polycrystalline film after they have been removed from the film deposition chamber and separated from the substrate holder. This is a schematic cross-sectional view showing the state in which the side surface of the second silicon carbide polycrystalline film has been removed to expose the second support substrate. This is a cross-sectional view showing the state in which the second support substrate has been removed from the second silicon carbide polycrystalline film. This is a cross-sectional view of the second silicon carbide polycrystalline film, which is the film deposited on the surface to be deposited on the second support substrate placed in the first position. This is a cross-sectional view of the second silicon carbide polycrystalline film, which is a film deposited on the film deposition target surface of the second support substrate disposed at the second position. This is an example of a record of measured values. This is a schematic diagram showing the arrangement of the first support substrate in the film deposition chamber in a modified embodiment. This is 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 the arrangement shown in Figure 11A.

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

[0010] [Method for Manufacturing a Silicon Carbide Polycrystalline Film] Figure 1 is a flowchart of the 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 film-forming surface of the support substrate is adjusted based on the measured curvature of the surface of the silicon carbide polycrystalline film obtained in the prototype stage S100; 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> 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 manufacturing stage S300, so as to prevent the production of silicon carbide polycrystalline films with surface warping outside the acceptable range in manufacturing stage S300. Prototype stage S100 can be performed before 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 raw material gas and carrier gas, the temperature and pressure atmosphere during film deposition, the replacement of the substrate holder, or the change in the rotation speed of the support substrate. 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 to be film-deposited, it is also film-deposited on the side surface 103 by performing the film-depositing treatment on the surface 101 and back surface 102.

[0015] The surface 101 and the back surface 102 are curved into a concave or convex shape, or other shape, on which a silicon carbide polycrystalline film can be formed, or they are flat, or they may be a combination of curved and flat surfaces.

[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 step: 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 may be set.

[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 is given of a case in which 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, but the present invention is not limited thereto. 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] (Step S102 for placing the first support substrate in the furnace) Step S102 is the step of placing the first support substrate 100 in 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 in the furnace, or multiple first support substrates 100 may be placed. 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 in 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 lateral 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 film 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 film-deposited are parallel and the centers of the substrates are on the same straight line, in order to improve unevenness in film deposition of the silicon carbide polycrystalline film 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 example, the first position 1100 and the a-position 1100a) for arranging the first support substrate within the film deposition chamber 1001, and the amount of curvature of the film deposition target surface of each first support substrate. This record can be used to determine the amount of curvature of the front surface 701 and back surface 702, which will be the film deposition target surfaces of the second support substrate 700, as described later.

[0029] (First film formation process S103) Figures 4A to 4D are schematic cross-sectional views of the first silicon carbide polycrystalline film 400 in the first film formation process S103, the first grinding process S104, and the first removal process S105.

[0030] FIG. 4A is a schematic cross-sectional view showing a state after a first silicon carbide polycrystalline film 400, 400a, etc. are formed on first support substrates 100, 100a, etc. held by a substrate holder in a film formation chamber 1001 of a film forming apparatus 1000, and FIG. 4B is a schematic cross-sectional view showing the first support substrates 100, 100a and the first silicon carbide polycrystalline films 400, 400a after being taken out from the film formation chamber 1001 and separated from the substrate holder.

[0031] The first film formation step S103 is a step of forming first silicon carbide polycrystalline films 400, 400a, etc. on the film formation target surfaces of the first support substrates 100, 100a, etc. by CVD method after the first support substrate furnace internal arrangement step S102. The first silicon carbide polycrystalline film 400 can be obtained by causing a gas phase reaction of a raw material gas such as a silicon-based raw material gas and a carbon-based raw material gas and depositing it on the film formation target surface of the first support substrate 100.

[0032] As the silicon-based raw material gas, for example, silane (SiH ４ ), in addition to which monochlorosilane (SiH ３ Cl), dichlorosilane (SiH ２ Cl ２ ), trichlorosilane (SiHCl ３ ), tetrachlorosilane (SiCl ４ ), etc., a chlorine-based silicon raw material-containing gas (chloride-based raw material) containing Cl having an etching action can also be used.

[0033] Also, as the carbon-based raw material gas, for example, methane (CH ４ ), propane (C ３ H ８ ), acetylene (C ２ H ２ ), etc., hydrocarbon gases can be used.

[0034] In addition to the above, trichloromethylsilane (CH ３ Cl ３ Si), trichlorophenylsilane (C ６ H ５ Cl ３ Si), dichloromethylsilane (CH ４ Cl ２ Si), dichlorodimethylsilane ((CH３ ) ２ SiCl ２ ), chlorotrimethylsilane ((CH ３ ) ３ SiCl), tetramethylsilane ((CH ３ ) ３ Gases containing both silicon and carbon, such as SiH, 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 a plurality of 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 hinder 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-forming surface of the first support substrate 100.

[0036] The dopant gas is an impurity doping gas supplied simultaneously with the source gas, in an amount corresponding to the target conductivity. For example, if the conductivity type is n-type, nitrogen (N) is used. ２ ) gas, or in the case of a p-type gas, trimethylaluminum (TMA) gas can be used.

[0037] The carrier gas is a gas that can be used simultaneously with the raw material gas and the 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. An example of a carrier gas is hydrogen (H), which has excellent thermal conductivity and an etching effect on silicon carbide. ２ Examples include:

[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 about 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, SiCl ４ CH as a carbon-containing gas ４ H as a carrier gas ２ N as a gas, impurity doping gas. ２ In the case of a gas mixture, the volume ratio of the gas mixture is SiCl ４ :CH ４ : H ２ : N ２ = It can be set to 1:1:10:1 to 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 in 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 step S104) Figure 4C is a schematic cross-sectional view of the state in which the side surfaces 401 and 401a of the first silicon carbide polycrystalline film 400 and 400a have been removed to expose the first support substrates 100 and 100a. The first grinding step S104 is a step of grinding or polishing the side surfaces 401 and 401a of the first silicon carbide polycrystalline film 400 and 400a until the side surfaces of the multiple first support substrates 100 and 100a are exposed. 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.

[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 with the first silicon carbide polycrystalline film is exposed. If the first removal step S105 described later can be performed by this exposure, the first grinding step S104 can be omitted.

[0046] (First Removal Step S105) Figure 4D is a schematic 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 removing them by burning through 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 the front and back surfaces of the first support substrate, which are the surfaces to be deposited on, two first silicon carbide polycrystalline films can be obtained from one first support substrate after the first removal step S105. That is, 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> Adjustment stage S200 is a stage in which the curvature of the film-forming 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 prototype stage S100. Adjustment stage S200 includes, for example, the following steps.

[0052] (First Warpage Measurement Step 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 Figures 5A to 5C.

[0053] Figure 5A 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 disposed at the first position 1100, and Figure 5B 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 disposed at the second position 1100a.

[0054] If, in the step prior to this step, 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 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 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 (Figures 5A and 5B) of the surfaces 411, 421, 411a, and 421a (Figures 5A and 5B) of the first silicon carbide polycrystalline films 410, 420, 410a, and 420a, linked to these records.

[0055] Figure 5C shows an example of recording measured values. For example, one recording method is to provide a column on the far left for the first position 1100, the second position 1100a, etc., 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, etc., ○○○○, △△△△, etc., 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 ○○○○, △△△△, etc.

[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 is 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 center line. 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 step 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 cited.

[0059] Figure 6, which shows the setting of the curvature amount of the film deposition target surface of the second support substrate, is a scatter plot obtained by representing the surface curvature of the first silicon carbide polycrystalline film as points against the curvature amount of the film deposition target surface of the first support substrate, and is further a graph showing the straight line of a linear function obtained by linear regression based on the scatter plot as a dotted line. The X axis of the graph is the curvature amount of the film deposition target surface of the first support substrate X １ The Y-axis represents the amount of curvature of the surface of the first silicon carbide polycrystalline film. １ This is the result. Figure 6 shows the amount of warpage on the surface of the first silicon carbide polycrystalline film, which was actually deposited using the first support substrate under predetermined conditions. Details of the deposition test for the first silicon carbide polycrystalline film will be described in the <Specific Examples> section below.

[0060] In Figure 6, the curvature of the surface to be deposited on the first support substrate was varied, and a first silicon carbide polycrystalline film with a thickness of 1300 μm was deposited under condition A. The curvature of the film was plotted at four points marked with ●. Based on this plot, a linear function (Y) was drawn. １ = aX １The dotted line shows the slope of the line (where "a" is a constant). The same applies to the plots of ◆, ▲, ○, ◇, 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 film 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, the linear function Y １ = aX １ Using this, a target value for the surface curvature of the second silicon carbide polycrystalline film is set, and the curvature of the film-forming surface of the second support substrate is calculated. Specifically, the curvature of the film-forming surface of the second support substrate is X ２ The target value for the surface curvature of the second silicon carbide polycrystalline film is Y. Ｇ２ Therefore, the equation of the linear function can be set as shown in equation 0 below.

[0063] [Equation 0] a = (Y １ -Y Ｇ２ ) / (X １ -X ２ ) ... (0)

[0064] In equation (0), the slope a is on the left side, and by moving the term in equation (0) to the left side, we get X ２ Then we get equation (1).

[0065] [Formula 1] ２ = X １ - (Y １ -Y Ｇ２ ) / a...(1)

[0066] In other words, the linear function Y is shown in the scatter plot in Figure 6. １ = aX １ Determine the target value Y for the surface curvature of the second silicon carbide polycrystalline film. Ｇ２ By setting this, the curvature X of the film deposition target surface of the second support substrate ２ It is possible to calculate this.

[0067] The second silicon carbide polycrystalline film may be used in silicon carbide bonded substrates 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 techniques such as exfoliation by ablation of hydrogen atoms. During this process, the silicon carbide polycrystalline substrate may be transported by vacuum adsorption using adsorption pads. However, if the silicon carbide polycrystalline substrate is significantly warped, air may leak, preventing vacuum adsorption by the adsorption pads, resulting in transport errors and affecting the productivity of the silicon carbide bonded substrate. Furthermore, this transport method may be used not only when bonding with silicon carbide single crystals but also in other processes in the manufacturing of silicon carbide bonded substrates.

[0068] Therefore, it is important that the second silicon carbide polycrystalline film has minimal warping. Target value Y for surface warping of the second silicon carbide polycrystalline film. Ｇ２ This can be set arbitrarily. For example, considering the transport error problem described above, the target value Y for the surface curvature of the second silicon carbide polycrystalline film can be set. Ｇ２ -100 μm ≤ Y Ｇ２ It may also be set so that ≤ +100 μm. Here, Y Ｇ２ If Y is 0, the surface of the second silicon carbide polycrystalline film is flat and not curved. Similarly, Ｇ２ When it is +100 μm, the surface of the second silicon carbide polycrystalline film is convex by 100 μm, Y Ｇ２ When the value is -100 μm, the surface of the second silicon carbide polycrystalline film is curved in a concave shape by 100 μm.

[0069] In Figure 6, Y １ A straight line is drawn for the cases of +100 μm and -100 μm, and Y is between these lines. Ｇ２ By setting X ２ This can be determined. For example, in the case of the film deposition conditions plotted as ●, the linear function shown by the dotted line (Y １ = aX １ According to Y １ X when +100 μm ２ As indicated by the downward arrow, it is approximately +100 μm, Y １ X when it is 0 μm ２It is approximately 0 μm, Y １ X when -100 μm ２ As indicated by the upward arrow, it is approximately -135 μm. In other words, for the film deposition conditions plotted as ●, X2 should be within the range of -135 μm to +100 μm, but if set to 0 μm, even considering some manufacturing errors, Y Ｇ２ is -100 μm ≤ 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 procedure is the same as described above, Y Ｇ２ -100 μm ≤ Y Ｇ２ X ２ It can be calculated and set.

[0071] Furthermore, the optimal value for the warpage of the second silicon carbide polycrystalline film cannot be determined in general, 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 -100 μm ≤ 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, the amount of curvature of the second support substrate can be set by creating scatter plots, etc., based on the results obtained from the film deposition based on those changes.

[0073] <Specific Example> Ten graphite support substrates, each with a diameter of 170 mm and a flat surface with a curvature of 0 μm on both the front surface 101 and the back surface 102, were used as the first support substrate 100. A first silicon carbide polycrystalline film 400 was deposited using a film deposition apparatus 1000. The gas flow rate volume ratio conditions during film deposition were SiCl ４ :CH ４ : H ２ : N ２The ratios were 1:1:10:1 to 100, with three conditions A, B, and C selected in advance. The first silicon carbide polycrystalline film 400 was deposited so that its thickness was between 600 μm and 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 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 to obtain a total of 20 first silicon carbide polycrystalline films 410 and 420, each with a diameter of 6 inches. The warpage of these films was measured, and the average value was calculated.

[0076] Based on the results so far, the curvature X of the film deposition target surface of the first support substrate 100 is １ The thickness is 0 μm, and the curvature Y of the surface of the first silicon carbide polycrystalline film 400. １ The particle size was 30 μm (see the ● plot in Figure 6).

[0077] Next, the curvature of the film deposition target surface of 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 (Y) was drawn. １ = aX １ ) is shown by a dotted line in Figure 6.

[0078] In the same manner as in the above test “Condition A, film thickness 1300 μm”, tests of “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” were conducted. Similarly, the average value of the warp of the surface of the first silicon carbide polycrystalline film 400 was calculated and plotted in Fig. 6 (see ◆, ▲, 〇, ◇, △ in Fig. 6), and a straight line of a linear function (Y １ = aX １ ) was shown by a dotted line in Fig. 6.

[0079] Through these tests, an experiment was conducted to confirm the warp of the first silicon carbide polycrystalline film 400 by changing the film thickness within the range of 600 μm to 1300 μm under the same Condition A, and an experiment was conducted to confirm the warp of the first silicon carbide polycrystalline film 400 by changing from Condition A to Condition B and Condition C and depositing films so that the film thickness was 800 μm in each case.

[0080] From the results shown in Fig. 6, for any straight line of the linear function (Y １ = aX １ ), the slope a satisfied 0.75 ≤ a ≤ 0.90.

[0081] - Curving the film-forming target surface of the second support substrate After performing the above “・Setting the amount of curvature of the film-forming target surface of the second support substrate”, the film-forming target surface of the second support substrate used in the manufacturing step S300 described below is curved so as to have the set amount of curvature X ２ . It is important to use a second support substrate that is exactly the same as the first support substrate 100 except for the curved shape of the film-forming target surface. Therefore, a second support substrate is prepared by using the same material as the first support substrate 100 and performing curving so that the shape is the same except for the film-forming target surface. Specifically, the material for the second support substrate is selected as follows, and grinding, polishing, etc. are performed while controlling the amount of curvature on the film-forming target surface to confirm and manage the amount of curvature.

[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, the surface to be coated has a curvature amount X. ２ You can purchase and use a substrate, but for example, you can also use a graphite disc with a thickness of 300 μm to 10 mm, cut in parallel, 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 amount of curvature of the film-forming surface of the second support substrate before forming the second silicon carbide polycrystalline film.

[0087] Figure 7A 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 the CVD method. Although the side surface 703 is not intended to be coated, 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 shown in Figure 7B also has a surface 701a, a back surface 702a, and a side surface 703a. Figures 7A and 7B show, as an example, second support substrates 700 and 700a with 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 stage S300, silicon carbide is deposited on a second support substrate having a film deposition surface with an adjusted curvature to obtain a second silicon carbide polycrystalline film with reduced surface warping. Manufacturing stage S300 includes, for example, the following steps.

[0091] (Second support substrate 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, it may be confirmed in this step whether the curvature of the film deposition surface is appropriate.

[0092] (Second support substrate in furnace placement process S302) The second support substrate in furnace placement process S302 is a process of placing the second support substrates 700, 700a, etc. (sometimes the "second support substrates 700, 700a, etc." are collectively referred to as the "second support substrate 700") in the film deposition chamber 1001 of the film 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 a 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 a substrate holder (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 left end, the second support substrate 700a placed in the 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 "...". The position in the substrate holder where the second support substrate 700 is placed is the first position 1100, and the position where the second support substrate 700a is placed in the a position from the left 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 rows 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 formation step S303 is a step in which a silicon carbide polycrystalline film is formed in the same manner as the first film formation step S103, except that the second support substrate 700 is used instead of the first support substrate 100.

[0097] Figures 9A to 9D are schematic cross-sectional views 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 9A is a schematic cross-sectional view showing 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. Figure 9B shows a schematic cross-sectional view of 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 in which, after the second support substrate in-furnace placement step S302, 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 step S304) The second grinding step S304 is a step, similar to the first grinding step S104, in which the sides 801, 801a of the second silicon carbide polycrystalline film 800, 800a are removed to expose the second support substrate 700, 700a, as shown in Figure 9C. 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 9D 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. That is, second silicon carbide polycrystalline films 810 and 820 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 Warpage of a Silicon Carbide Polycrystalline Film] Next, an example of the method for evaluating the warpage of a silicon carbide polycrystalline film according to the present invention will be explained. For example, as described above, the second silicon carbide polycrystalline film can be mass-produced by repeating the procedure of "bending the surface of the second support substrate to be deposited" and <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 surface warpage of the obtained second silicon carbide polycrystalline film. In that case, by performing the same procedure as in <Adjustment step S200> to adjust the curvature of the surface to be deposited on the support substrate to be used thereafter based on the measurement of the curvature of the surface of the second silicon carbide polycrystalline film, and then performing the same procedure as in <Manufacturing step S300> to deposit the silicon carbide polycrystalline film, the variation in the curvature of the surface of the resulting silicon carbide polycrystalline film can be reduced.

[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 step S200> and <manufacturing step 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 step S200> and <manufacturing step 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 process, 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 process will be further explained below using explanatory diagrams that supplement the explanation shown in Figures 10A to 10C.

[0113] Figure 10A 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 disposed at the first position 1100, and Figure 10B 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 disposed 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 step, 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 10C shows an example of recording measured values. For example, one recording method may involve providing a column on the far left for the first position 1100, the second position 1100a, etc., a column in the middle for the curvature amount of the film-forming surface of the second support substrate corresponding to the first position 1100, the second position 1100a, etc. (●●●●, ▲▲▲▲, etc.), and a column on the far right for the surface warpage amount of the second silicon carbide polycrystalline film corresponding to the curvature amount of the film-forming surface of the second support substrate (■■■■, ◆◆◆◆, etc.).

[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, these may be recorded separately. Similarly, for the second silicon carbide polycrystalline films 810a and 820a, if the warpage amounts 812a and 822a of the front surfaces 811a and 821a are different, 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 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.

[0118] (Second Curvature Amount Adjustment Process) In the second curvature amount adjustment process, the curvature amount of the film-forming surface of the third support substrate, which will be used as a support substrate after the second warp amount measurement process, is adjusted. Specifically, the procedure is the same as in the "First Curvature Amount Adjustment Process S202," by setting the curvature amount of the film-forming surface of the third support substrate and performing the curvature processing of the film-forming surface of the third support substrate.

[0119] For example, the setting of the amount of curvature of the film-forming target surface of the third support substrate can be obtained by preparing a scatter diagram representing the amount of warpage of the surface of the second silicon carbide polycrystalline film with respect to the amount of curvature of the film-forming target surface of the second support substrate in the same manner as in FIG. 6, and obtaining a straight line of a linear function.

[0120] Specifically, let the amount of curvature of the film-forming target surface of the second support substrate be X ２ , the amount of curvature of the film-forming target surface of the third support substrate be X ３ , the amount of warpage of the surface of the second silicon carbide polycrystalline film be Y ２ , and the target value of the amount of warpage of the surface of the third silicon carbide polycrystalline film be Y Ｇ３ . In this case, the amount of curvature X ３ [[ID=!]] of the film-forming target surface of the third support substrate can be adjusted to the amount of curvature calculated by the following formula (2).

[0121] [Formula 2] X ３ = X ２ - (Y ２ - Y <! Ｇ３ ) / b... (2)

[0122] In Formula 2, b is the slope of the linear function (Y ２ = bX ２ ) obtained by linear regression based on a scatter diagram representing the amount of warpage of the surface of the second silicon carbide polycrystalline film with respect to the amount of curvature of the film-forming target surface of the second support substrate, with the X-axis being X ２ and the Y-axis being Y ２ , that is, a constant.

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

[0124] Also, Y Ｇ３ can be set, for example, to satisfy -100 μm ≤ Y Ｇ３ ≤ +100 μm.

[0125] (Third film-forming step) In the third film-forming step, after the second curvature adjustment step, a third silicon carbide polycrystalline film with the amount of warpage of the surface adjusted is formed on the film-forming target surface of the third support substrate. The silicon carbide polycrystalline film may be formed in the same manner as in the second film-forming step S303. The same steps as in the second film-forming step S303 can be employed except that the third support substrate is used instead of the second support substrate 700.

[0126] It should be noted that there seems to be an error in the original text where "!0000103" is used. It should probably be "0000103" for correct mathematical expression. The above translation is based on the corrected understanding.(Third Warpage Measurement Process) In the third warpage measurement process, the amount of warpage on the surface of the third silicon carbide polycrystalline film is measured after the third film formation process and the removal of the third support substrate. The specific procedure can be carried out by referring to and imitating the "First Warpage Measurement Process," "Second Warpage Measurement Process," Figures 5A to 5C, Figure 6, and Figures 10A to 10C described above.

[0127] (Other steps) The method for producing a silicon carbide polycrystalline film of the present invention may include steps other than those described above. For example, these include a step of placing a third support substrate in the film deposition chamber (support substrate in furnace placement step), a step of 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 a step of 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] <Modifications> Below, we will further describe modifications of this embodiment 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 11A is a schematic diagram showing the arrangement of the first support substrate in the film deposition chamber in a modified embodiment, and Figure 11B is 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 the arrangement shown in Figure 11A.

[0133] The arrangement shown in Figure 11A 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 first support substrates 100 as shown in Figure 11A, a film deposition process was carried out to deposit a silicon carbide polycrystalline film onto the first 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 1001 in the deposition chamber was symmetrical and took on a gentle mountain shape, as shown in Figure 11B. 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 11B, 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 11B, 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-forming surface of the second support substrate was set for each group collectively. The curvature of the film-forming 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-forming 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 in the first group was 0 μm, in the second group it was +300 μm, and in the third group it was +400 μm. Therefore, the curvature of all 18 second support substrates in the first group was set to 0 μm, similarly, the curvature of all 6 substrates in the second group was 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 the 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 inside 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 the first curvature of the surface of a first silicon carbide polycrystalline film obtained by forming a film on the first film-forming surface of a first support substrate having a first film-forming surface for which the amount of curvature has been confirmed in advance, and a second film-forming step of forming a second silicon carbide polycrystalline film on the second film-forming surface of a second support substrate having a second film-forming surface for which the amount of curvature has been adjusted based on the evaluated first curvature.

[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 Elementary polycrystalline film, 401: Side surface, 401a: Side surface, 410: First silicon carbide polycrystalline film, 410a: First silicon carbide polycrystalline film, 411: Surface, 411a: Surface, 412 : amount of warping, 412a: amount of warping, 420: first silicon carbide polycrystalline film, 420a: first silicon carbide polycrystalline film, 421: surface, 421a: surface, 422: amount of warping, 422a: amount of warping, 700: second support substrate, 700a: second support substrate, 701: surface, 701a: surface, 702: back surface, 702a: back surface, 703: side surface, 70 3a: side surface, 800: second silicon carbide polycrystalline film, 800a: second silicon carbide polycrystalline film, 801: side surface, 801a: side surface, 810: second silicon carbide polycrystalline film, 810a: second silicon carbide polycrystalline film, 811: surface, 811a: surface, 812: amount of warpage, 812a: amount of warpage, 820: second silicon carbide polycrystalline film, 820a: second silicon Silicon polycrystalline film, 821: surface, 821a: surface, 822: warpage, 822a: warpage, 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: a position

Claims

1. A method for manufacturing a silicon carbide polycrystalline film, comprising a second film deposition step of depositing a second silicon carbide polycrystalline film 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 first silicon carbide polycrystalline film at a predetermined position on the film deposition surface of a first support substrate having a film deposition surface whose curvature has been confirmed in advance.

2. The method for producing a silicon carbide polycrystalline film according to claim 1, wherein 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.

3. Let the amount of curvature of the film-forming target surface of the first support substrate be X １ , and the amount of curvature of the film-forming target surface of the second support substrate be X ２ , let the amount of warp of the surface of the first silicon carbide polycrystalline film be Y １ , and the target value of the amount of warp of the surface of the second silicon carbide polycrystalline film be Y Ｇ２ . When a constant is a, the amount of curvature X ２ of the film-forming target surface of the second support substrate is adjusted to the amount of curvature calculated by the following formula (1). The method for manufacturing a silicon carbide polycrystalline film according to claim 1. [Formula (1)] X ２ = X １ - (Y １ - Y Ｇ２ ) / a... (1) 4. The method for producing a silicon carbide polycrystalline film according to claim 3, wherein a satisfies 0.75 ≤ a ≤ 0.

90.

5. A method for manufacturing a silicon carbide polycrystalline film according to claim 1, comprising: a first film formation step of forming a first silicon carbide polycrystalline film on the film-forming surface of the first support substrate; a first removal step of removing the first support substrate from the first silicon carbide polycrystalline film after the first film formation step; a first warpage measurement step of measuring the amount of warpage of the surface of the first silicon carbide polycrystalline film after the first removal step; a first curvature adjustment step of adjusting the amount of curvature of the film-forming surface of the second support substrate after the first warpage measurement step; and 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 method for manufacturing a silicon carbide polycrystalline film according to claim 1, wherein the second film formation step involves arranging the first support substrates at a plurality of different positions to adjust the curvature of the film formation target surface of the second support substrates, and arranging a plurality of second support substrates, each having a different curvature of the film formation target surface of the second support substrate, at the respective positions.

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

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