JP7338193B2 - Method for manufacturing polycrystalline silicon carbide substrate - Google Patents

Method for manufacturing polycrystalline silicon carbide substrate Download PDF

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JP7338193B2
JP7338193B2 JP2019062605A JP2019062605A JP7338193B2 JP 7338193 B2 JP7338193 B2 JP 7338193B2 JP 2019062605 A JP2019062605 A JP 2019062605A JP 2019062605 A JP2019062605 A JP 2019062605A JP 7338193 B2 JP7338193 B2 JP 7338193B2
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崇志 佐藤
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Sumitomo Metal Mining Co Ltd
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Description

本発明は、炭化ケイ素多結晶基板の製造方法に関する。 The present invention relates to a method for manufacturing a polycrystalline silicon carbide substrate.

炭化ケイ素は、ケイ素と炭素で構成される、化合物半導体材料である。炭化ケイ素は、絶縁破壊電界強度がケイ素の１０倍で、バンドギャップがケイ素の３倍であり、半導体材料として優れている。さらに、デバイスの作製に必要なｐ型、ｎ型の制御が広い範囲で可能であることなどから、ケイ素の限界を超えるパワーデバイス用材料として期待されている。また、炭化ケイ素は、従来の半導体材料より薄い厚さでも高い耐電圧が得られるため、炭化ケイ素を半導体材料とするときに、薄く構成することにより、ＯＮ抵抗が小さく、低損失の半導体が得られることが特徴である。 Silicon carbide is a compound semiconductor material composed of silicon and carbon. Silicon carbide has a dielectric breakdown field strength ten times that of silicon and a bandgap three times that of silicon, and is excellent as a semiconductor material. Furthermore, since it is possible to control the p-type and n-type necessary for device fabrication in a wide range, it is expected as a material for power devices that exceeds the limit of silicon. In addition, since silicon carbide can provide a high withstand voltage even when the thickness is thinner than that of conventional semiconductor materials, when silicon carbide is used as a semiconductor material, a semiconductor with low ON resistance and low loss can be obtained by making it thin. It is characterized by being able to

しかしながら、炭化ケイ素半導体は、従来広く普及しているケイ素半導体と比較して、大面積の炭化ケイ素単結晶基板を得ることが難しく、製造工程も複雑である。これらの理由から、炭化ケイ素半導体は、ケイ素半導体と比較して大量生産が難しく、高価であった。 However, it is difficult to obtain a silicon carbide single crystal substrate having a large area, and the manufacturing process is complicated, as compared with silicon semiconductors that have been widely used in the past. For these reasons, silicon carbide semiconductors are more difficult to mass-produce and more expensive than silicon semiconductors.

これまでにも、炭化ケイ素半導体のコストを下げるために、様々な工夫が行われてきた。例えば、特許文献１には、炭化ケイ素基板の製造方法であって、少なくとも、マイクロパイプの密度が３０個／ｃｍ２以下の炭化ケイ素単結晶基板（以下、「単結晶基板」と称することがある）と炭化ケイ素多結晶基板（以下、「多結晶基板」と称することがある）を準備し、単結晶基板と多結晶基板とを貼り合わせる工程を行い、その後、単結晶基板を薄膜化する工程を行い、多結晶基板上に単結晶層を形成した基板を製造することが記載されている。 Various attempts have been made so far to reduce the cost of silicon carbide semiconductors. For example, Patent Document 1 discloses a method for manufacturing a silicon carbide substrate, which includes at least a silicon carbide single crystal substrate having a micropipe density of 30/cm 2 or less (hereinafter sometimes referred to as a “single crystal substrate”). ) and a silicon carbide polycrystalline substrate (hereinafter sometimes referred to as “polycrystalline substrate”), performing a step of bonding the single crystal substrate and the polycrystalline substrate together, and then thinning the single crystal substrate. to manufacture a substrate in which a single crystal layer is formed on a polycrystalline substrate.

更に、特許文献１には、単結晶基板と多結晶基板とを貼り合わせる工程の前に、単結晶基板に水素イオン注入を行って水素イオン注入層を形成する工程を行い、単結晶基板と多結晶基板とを貼り合わせる工程の後、単結晶基板を薄膜化する工程の前に、３５０℃以下の温度で熱処理を行い、水素イオン注入層にて機械的に剥離することにより単結晶基板を薄膜化することが記載されている。 Furthermore, in Patent Document 1, a step of implanting hydrogen ions into the single crystal substrate to form a hydrogen ion-implanted layer is performed before the step of bonding the single crystal substrate and the polycrystalline substrate together. After the step of bonding the crystal substrate and before the step of thinning the single crystal substrate, a heat treatment is performed at a temperature of 350° C. or less, and the single crystal substrate is mechanically separated at the hydrogen ion implanted layer to thin the single crystal substrate. It is described that

このような方法により、１つの炭化ケイ素単結晶インゴットからより多くの炭化ケイ素貼り合わせ基板が得られるようになった。 Such a method has made it possible to obtain a larger number of silicon carbide bonded substrates from one silicon carbide single crystal ingot.

特開２００９－１１７５３３号公報JP 2009-117533 A

特許文献１に記載された炭化ケイ素基板の製造方法は、水素イオン注入を行って薄いイオン注入層が形成された炭化ケイ素単結晶基板と、炭化ケイ素多結晶基板と、を貼り合わせたのちに加熱して、水素イオン注入層において単結晶基板の一部を剥離して単結晶基板を薄膜化することによって製造されている。このことから、特許文献１に記載された炭化ケイ素基板は、製造された炭化ケイ素基板の厚さの大部分が多結晶基板に由来する。このため、特許文献１の炭化ケイ素基板には、研磨などのハンドリングの際に炭化ケイ素基板が損傷しないようにするため、機械的な強度を有する十分な厚さの多結晶基板を使用する。そのため、半導体として機能するために必要な厚さよりも、大きな厚さを有する多結晶基板を用いる必要があった。 In the method for manufacturing a silicon carbide substrate described in Patent Document 1, a silicon carbide single crystal substrate on which a thin ion-implanted layer is formed by hydrogen ion implantation and a silicon carbide polycrystalline substrate are bonded together and then heated. Then, a part of the single-crystal substrate is peeled off in the hydrogen ion-implanted layer to thin the single-crystal substrate. For this reason, most of the thickness of the manufactured silicon carbide substrate of the silicon carbide substrate described in Patent Document 1 is derived from the polycrystalline substrate. Therefore, for the silicon carbide substrate of Patent Document 1, a polycrystalline substrate having a sufficient thickness and having mechanical strength is used so as not to damage the silicon carbide substrate during handling such as polishing. Therefore, it was necessary to use a polycrystalline substrate having a thickness greater than the thickness required to function as a semiconductor.

また、炭化ケイ素多結晶基板の抵抗値が高いと、ＯＮ抵抗が大きくなり、本来の炭化ケイ素半導体の特徴を充分に発揮されなくなる可能性があった。 Moreover, when the resistance value of the polycrystalline silicon carbide substrate is high, the ON resistance increases, and there is a possibility that the original characteristics of the silicon carbide semiconductor cannot be fully exhibited.

すなわち、炭化ケイ素基板の製造工程において炭化ケイ素基板の損傷を防ぐためには、機械的強度を有する程度の多結晶基板の厚さが必要である。また、得られる炭化ケイ素半導体のＯＮ抵抗を小さくするためには、多結晶基板の抵抗値が低い必要があった。 That is, in order to prevent damage to the silicon carbide substrate in the manufacturing process of the silicon carbide substrate, the polycrystalline substrate must be thick enough to have mechanical strength. Moreover, in order to reduce the ON resistance of the obtained silicon carbide semiconductor, the resistance value of the polycrystalline substrate must be low.

従来、炭化ケイ素基板は、化学蒸着法等の気相成長法において窒素等のドーパントを加えながら、所定の厚さまで成膜することにより得られていた。図４は、従来の炭化ケイ素多結晶基板の製造工程を説明する、支持基板および炭化ケイ素多結晶膜等の側面図である。ここで、図４（Ａ）は支持基板５１０の両面に厚い炭化ケイ素多結晶膜５２０ａ、５２０ｂを成膜した状態である、蒸着基板５００の断面を示す模式図であり、図４（Ｂ）は、蒸着基板５００から、支持基板５１０を除去して得られた炭化ケイ素多結晶膜５２０ａ’、５２０ｂ’に反りが発生した状態の断面を示す模式図であり、図４（Ｃ）は、反りが発生した炭化ケイ素多結晶膜５２０ａ’、５２０ｂ’の反り部分を研磨等により除去して得られた、炭化ケイ素多結晶基板５２１の断面を示す模式図である。 Conventionally, a silicon carbide substrate has been obtained by forming a film to a predetermined thickness while adding a dopant such as nitrogen in a chemical vapor deposition method or other chemical vapor deposition method. FIG. 4 is a side view of a supporting substrate, a polycrystalline silicon carbide film, etc., for explaining a manufacturing process of a conventional polycrystalline silicon carbide substrate. Here, FIG. 4A is a schematic diagram showing a cross section of the vapor deposition substrate 500 in a state where thick polycrystalline silicon carbide films 520a and 520b are formed on both sides of the supporting substrate 510, and FIG. 4A and 4B are schematic cross-sectional views showing warping of polycrystalline silicon carbide films 520a′ and 520b′ obtained by removing a support substrate 510 from a vapor deposition substrate 500, and FIG. 5 is a schematic diagram showing a cross section of a polycrystalline silicon carbide substrate 521 obtained by removing warped portions of polycrystalline silicon carbide films 520a′ and 520b′ by polishing or the like. FIG.

炭化ケイ素多結晶基板５２１ａ、５２１ｂは、母材となるケイ素支持基板もしくは黒鉛支持基板等の支持基板５１０に、熱化学蒸着法等の化学蒸着によって、炭化ケイ素多結晶膜５２０ａ、５２０ｂを成膜して蒸着基板５００を得た後、支持基板５１０を除去することで得られる。しかしながら、炭化ケイ素多結晶膜を成膜する場合、支持基板５１０の表面から炭化ケイ素の多結晶の成長が始まるため、炭化ケイ素多結晶膜５２０ａ、５２０ｂの厚さが大きくなるほど炭化ケイ素の結晶粒が大きくなり、炭化ケイ素多結晶膜５２０ａ、５２０ｂにひずみが入りやすい。このため、支持基板５１０から炭化ケイ素多結晶膜５２０ａ、５２０ｂを剥離した際に、図４（Ｂ）に示すように、炭化ケイ素多結晶膜５２０ａ’、５２０ｂ’に大きな反りが発生してしまうことがあった。 Polycrystalline silicon carbide substrates 521a and 521b are formed by forming silicon carbide polycrystalline films 520a and 520b by chemical vapor deposition such as thermal chemical vapor deposition on a supporting substrate 510 such as a silicon supporting substrate or a graphite supporting substrate as a base material. After obtaining the vapor deposition substrate 500, the support substrate 510 is removed. However, when the polycrystalline silicon carbide film is formed, polycrystalline silicon carbide starts to grow from the surface of the support substrate 510. Therefore, as the thickness of the polycrystalline silicon carbide films 520a and 520b increases, the crystal grains of silicon carbide increase. As a result, the silicon carbide polycrystalline films 520a and 520b are likely to be strained. Therefore, when the polycrystalline silicon carbide films 520a and 520b are separated from the supporting substrate 510, the polycrystalline silicon carbide films 520a' and 520b' are greatly warped as shown in FIG. 4B. was there.

大きな反りが発生した場合には、図４（Ｂ）に示すように、必要な厚さＴの炭化ケイ素多結晶基板５２１ａ、５２１ｂを得るために、反りが発生した部分を、例えば線Ａ、線Ａ’の部分まで、研磨等により削り落とす必要がある。そのため、研磨する前の炭化ケイ素多結晶膜５２０ａ、５２０ｂの膜厚は、発生し得る反りを含めた厚さを考慮して、支持基板５１０上に炭化ケイ素多結晶膜５２０ａ、５２０ｂを厚く成膜する必要がある。つまり、削り落とす分を考慮してより厚い膜を成膜し、さらに研磨の難しい硬い炭化ケイ素を研磨しなければならず、炭化ケイ素多結晶膜５２０ａ、５２０ｂの成膜時に発生する反りが、炭化ケイ素多結晶基板５２１ａ、５２１ｂの生産性、さらには炭化ケイ素基板の生産性の低下に大きな影響を与えている。 When a large warp occurs, as shown in FIG. 4(B), in order to obtain silicon carbide polycrystalline substrates 521a and 521b with a required thickness T, the warped portion is removed, for example, by line A, line It is necessary to scrape off by polishing or the like up to the portion of A'. Therefore, the film thickness of the polycrystalline silicon carbide films 520a and 520b before polishing is such that the polycrystalline silicon carbide films 520a and 520b are formed thickly on the support substrate 510 in consideration of the thickness including the warpage that may occur. There is a need to. In other words, it is necessary to form a thicker film in consideration of the amount to be scraped off, and to polish hard silicon carbide, which is difficult to polish. This greatly affects the productivity of the polycrystalline silicon substrates 521a and 521b and the productivity of the silicon carbide substrate.

従って、本発明は、上記のような問題点に着目し、炭化ケイ素多結晶基板に発生し得る反り量の低減が可能な炭化ケイ素多結晶基板の製造方法を提供することを目的とする。 Accordingly, it is an object of the present invention to provide a method for manufacturing a polycrystalline silicon carbide substrate that can reduce the amount of warpage that may occur in the polycrystalline silicon carbide substrate, focusing on the above problems.

本発明の炭化ケイ素多結晶基板の製造方法は、化学蒸着により支持基板の成膜対象面に第１炭化ケイ素多結晶膜を成膜させた後、前記支持基板を除去して得られる、膜厚が５０μｍ～２５０μｍの炭化ケイ素多結晶支持基板の成膜対象面に、化学蒸着により第２炭化ケイ素多結晶膜を成膜する成膜工程を含む。 In the method for producing a polycrystalline silicon carbide substrate of the present invention, after forming a first polycrystalline silicon carbide film on a film-forming target surface of a support substrate by chemical vapor deposition, the film thickness obtained by removing the support substrate is a film forming step of forming a second polycrystalline silicon carbide film by chemical vapor deposition on the film formation target surface of the polycrystalline silicon carbide support substrate having a thickness of 50 μm to 250 μm.

また、本発明の炭化ケイ素多結晶基板の製造方法において、前記成膜工程で成膜する前記第２炭化ケイ素多結晶膜の厚さが、７０μｍ以上であってもよい。 Further, in the method for manufacturing a polycrystalline silicon carbide substrate of the present invention, the second polycrystalline silicon carbide film formed in the film forming step may have a thickness of 70 μm or more.

また、本発明の炭化ケイ素多結晶基板の製造方法において、前記第１炭化ケイ素多結晶膜の成膜時において、前記第１炭化ケイ素多結晶膜の原料ガスの噴出位置からの噴出方向と、前記支持基板の成膜対象面と、が垂直であり、前記成膜工程において、前記第２炭化ケイ素多結晶膜の原料ガスの噴出位置からの噴出方向と、前記炭化ケイ素多結晶支持基板の成膜対象面と、が垂直であり、前記炭化ケイ素多結晶支持基板の前記成膜対象面が、前記第１炭化ケイ素多結晶膜の成膜時に、前記第１炭化ケイ素多結晶膜の前記原料ガスの噴出位置と対向する第１面と、前記第１面の裏側の面となる第２面と、からなり、前記第２面を、前記第２炭化ケイ素多結晶膜の原料ガスの噴出位置に向けて、前記第２炭化ケイ素多結晶膜を成膜させてもよい。 Further, in the method for manufacturing a silicon carbide polycrystalline substrate of the present invention, when forming the first polycrystalline silicon carbide film, the direction of ejection from the position where the source gas of the first polycrystalline silicon carbide film is ejected; is perpendicular to the film formation target surface of the support substrate, and in the film formation step, the ejection direction from the ejection position of the raw material gas for the second polycrystalline silicon carbide film and the film formation of the polycrystalline silicon carbide support substrate. is perpendicular to the target surface, and the film formation target surface of the polycrystalline silicon carbide support substrate is exposed to the source gas of the first polycrystalline silicon carbide film during the formation of the first polycrystalline silicon carbide film. It is composed of a first surface facing an ejection position and a second surface that is a surface on the back side of the first surface, and the second surface faces the ejection position of the raw material gas of the second polycrystalline silicon carbide film. Alternatively, the second silicon carbide polycrystalline film may be deposited.

また、本発明の炭化ケイ素多結晶基板の製造方法において、前記成膜工程において、前記炭化ケイ素多結晶支持基板の両面に、前記第２炭化ケイ素多結晶膜を成膜してもよい。 Moreover, in the method for manufacturing a polycrystalline silicon carbide substrate of the present invention, in the film forming step, the second polycrystalline silicon carbide films may be formed on both surfaces of the polycrystalline silicon carbide support substrate.

本発明の炭化ケイ素多結晶基板の製造方法であれば、炭化ケイ素多結晶基板に発生し得る反り量の低減が可能となる。 With the method for manufacturing a polycrystalline silicon carbide substrate of the present invention, it is possible to reduce the amount of warpage that may occur in the polycrystalline silicon carbide substrate.

本発明の一実施形態にかかる炭化ケイ素多結晶基板の製造方法において用いられる成膜装置の一例を模式的に示す側面断面図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side cross-sectional view schematically showing an example of a film forming apparatus used in a method for manufacturing a polycrystalline silicon carbide substrate according to one embodiment of the present invention; 本発明の一実施形態における製造工程を説明する、支持基板および炭化ケイ素多結晶膜等の側面図である。FIG. 2A is a side view of a support substrate, a silicon carbide polycrystalline film, etc., for explaining a manufacturing process in one embodiment of the present invention; 炭化ケイ素多結晶基板の製造方法の変形例において、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を成膜室１０１０内に載置した状態を示す図である。FIG. 10 is a diagram showing a state in which polycrystalline silicon carbide support substrates 220a' and 220b' are placed in a film formation chamber 1010 in a modification of the method for manufacturing a polycrystalline silicon carbide substrate. 従来の炭化ケイ素多結晶基板の製造工程を説明する、支持基板および炭化ケイ素多結晶膜等の側面図である。It is a side view of a support substrate, a silicon carbide polycrystalline film, etc. explaining the manufacturing process of the conventional silicon carbide polycrystalline substrate.

本発明の第一実施形態にかかる炭化ケイ素多結晶基板２０００の製造方法について、図面を参照して説明する。 A method for manufacturing a silicon carbide polycrystalline substrate 2000 according to the first embodiment of the present invention will be described with reference to the drawings.

本実施形態の炭化ケイ素多結晶基板２０００の製造方法は、図１、図２に示すように、化学蒸着により支持基板２１０の表面２１０ａと裏面２１０ｂの両面を成膜対象面として第１炭化ケイ素多結晶膜２２０ａ、２２０ｂを成膜させ（図２（Ａ））、その後、支持基板２１０を除去して得られる膜厚が５０μｍ～２５０μｍの炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の表面２２０ａ１、２２０ｂ１と裏面２２０ａ２、２２０ｂ２の両面に（図２（Ｂ））、化学蒸着により第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜する成膜工程を含むものである（図２（Ｃ））。第１炭化ケイ素多結晶膜２２０ａ、２２０ｂ、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの成膜は、例えば、図１に示す成膜装置１０００を用いることができる。なお、本実施形態において、図２（Ａ）に示すように、支持基板２１０に第１炭化ケイ素多結晶膜２２０ａ、２２０ｂが成膜された状態のものを蒸着基板２００と称する。なお、片面のみ成膜されたものも蒸着基板とする。また、本実施形態の炭化ケイ素多結晶基板２０００の製造方法は、例えば、基板の厚さが３００μｍ～７００μｍ程度の炭化ケイ素多結晶基板の製造に好適な製法である。 As shown in FIGS. 1 and 2, the method for manufacturing the polycrystalline silicon carbide substrate 2000 of the present embodiment is performed by chemical vapor deposition using both the front surface 210a and the rear surface 210b of the support substrate 210 as film formation target surfaces. Crystal films 220a and 220b are deposited (FIG. 2(A)), and then surfaces 220a1 of silicon carbide polycrystalline support substrates 220a' and 220b' having a film thickness of 50 μm to 250 μm obtained by removing the support substrate 210, 220b1 and back surfaces 220a2 and 220b2 (FIG. 2(B)), a film forming step of forming second silicon carbide polycrystalline films 230a and 230b by chemical vapor deposition (FIG. 2(C)). For the deposition of the first polycrystalline silicon carbide films 220a, 220b and the second polycrystalline silicon carbide films 230a, 230b, for example, the film deposition apparatus 1000 shown in FIG. 1 can be used. In this embodiment, as shown in FIG. 2A, a support substrate 210 on which the first polycrystalline silicon carbide films 220a and 220b are formed is referred to as a vapor deposition substrate 200. As shown in FIG. Note that a substrate on which a film is formed only on one side is also regarded as a vapor deposition substrate. Moreover, the method for manufacturing the silicon carbide polycrystalline substrate 2000 of the present embodiment is suitable for manufacturing a silicon carbide polycrystalline substrate having a substrate thickness of about 300 μm to 700 μm, for example.

成膜装置１０００は、化学蒸着により、支持基板２１０または炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’に炭化ケイ素多結晶膜を成膜させることができる。図１では、支持基板２１０を成膜装置１０００に供した状態を例示する。成膜装置１０００は、成膜装置１０００の外装となる筐体１１００と、支持基板２１０または炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’に炭化ケイ素多結晶膜を成膜させる成膜室１０１０と、成膜室１０１０より排出された原料ガスやキャリアガスを後述のガス排出口１０３０へ導入する排出ガス導入室１０４０と、排出ガス導入室１０４０を覆うボックス１０５０と、ボックス１０５０の外部より成膜室１０１０内を加温する、カーボン製のヒーター１０６０と、成膜室１０１０の下部に設けられ、成膜室１０１０に原料ガスやキャリアガスを導入するガス導入口１０２０と、ガス排出口１０３０と、支持基板２１０または炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を保持する基板ホルダー１０７０を有する。また、基板ホルダー１０７０は、２つの柱１０７１と、支持基板２１０または炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を水平に載置する、柱１０７１に設けられた載置部１０７２を有する。 The film forming apparatus 1000 can form a silicon carbide polycrystalline film on the support substrate 210 or the silicon carbide polycrystalline support substrates 220a' and 220b' by chemical vapor deposition. FIG. 1 illustrates a state in which the supporting substrate 210 is provided to the film forming apparatus 1000 . The film forming apparatus 1000 includes a housing 1100 serving as an exterior of the film forming apparatus 1000, a film forming chamber 1010 for forming a silicon carbide polycrystalline film on a supporting substrate 210 or silicon carbide polycrystalline supporting substrates 220a′ and 220b′, Exhaust gas introduction chamber 1040 for introducing raw material gas and carrier gas discharged from film formation chamber 1010 into gas discharge port 1030 described later, box 1050 covering exhaust gas introduction chamber 1040, and film formation chamber 1010 from outside box 1050. A heater 1060 made of carbon that heats the interior, a gas introduction port 1020 that is provided in the lower part of the film formation chamber 1010 and introduces a source gas and a carrier gas into the film formation chamber 1010, a gas discharge port 1030, and a support substrate. 210 or a substrate holder 1070 that holds a silicon carbide polycrystalline support substrate 220a', 220b'. The substrate holder 1070 also has two pillars 1071 and mounting portions 1072 provided on the pillars 1071 for horizontally mounting the support substrate 210 or the silicon carbide polycrystalline support substrates 220a' and 220b'.

第１炭化ケイ素多結晶膜２２０ａ、２２０ｂ、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの成膜時において、原料ガスやキャリアガス等は、成膜室１０１０に設けられたガス導入口１０２０から導入され、成膜室１０１０の下部から排出ガス導入室１０４０に排出され、さらに、ガス排出口１０３０から成膜装置１０００の外部に排出される。 During the deposition of the first polycrystalline silicon carbide films 220a and 220b and the second polycrystalline silicon carbide films 230a and 230b, source gas, carrier gas and the like are introduced from the gas introduction port 1020 provided in the deposition chamber 1010. , is discharged from the bottom of the film formation chamber 1010 into the exhaust gas introduction chamber 1040 , and further discharged from the film formation apparatus 1000 through the gas discharge port 1030 .

次に、本発明の一実施形態にかかる炭化ケイ素多結晶基板２０００の製造方法の一例として、前述の成膜装置１０００を用いる方法を説明する。以下の説明は本実施形態の炭化ケイ素多結晶基板２０００の製造方法の一例であり、問題のない範囲で温度、圧力、ガス雰囲気等の各条件や、手順等を変更してもよい。 Next, as an example of a method for manufacturing the silicon carbide polycrystalline substrate 2000 according to one embodiment of the present invention, a method using the aforementioned film forming apparatus 1000 will be described. The following description is an example of the method for manufacturing the silicon carbide polycrystalline substrate 2000 of the present embodiment, and the conditions such as temperature, pressure, gas atmosphere, etc., and the procedure may be changed within a range that causes no problem.

まず、成膜装置１０００において、化学蒸着により、支持基板２１０上に第１炭化ケイ素多結晶膜２２０ａ、２２０ｂを成膜させる。なお、支持基板２１０としては、後の工程で支持基板２１０を除去するときの容易性を考慮して、黒鉛製の支持基板やケイ素製の支持基板を好適に用いることができる。 First, in the film forming apparatus 1000, the first silicon carbide polycrystalline films 220a and 220b are formed on the support substrate 210 by chemical vapor deposition. As the support substrate 210, a support substrate made of graphite or a support substrate made of silicon can be preferably used in consideration of ease of removing the support substrate 210 in a later step.

支持基板２１０を載置部１０７２に載置し、減圧状態で、Ａｒ等の不活性ガス雰囲気下で、成膜の反応温度まで、ヒーター１０６０により支持基板を加熱する。成膜の反応温度（例えば、１２００℃程度）まで達したら、不活性ガスの供給を止めて、成膜室１０１０内に第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成分を含む原料ガスやキャリアガスを供給する。支持基板２１０の成膜対象面や気相での化学反応により、加熱した支持基板２１０の両面に第１炭化ケイ素多結晶膜２２０ａ、２２０ｂを成膜させることができる。これにより、図２（Ａ）に示すように、支持基板２１０に第１炭化ケイ素多結晶膜２２０ａ、２２０ｂが成膜された、蒸着基板２００が得られる。 The supporting substrate 210 is placed on the mounting portion 1072, and the supporting substrate is heated by the heater 1060 to the film formation reaction temperature in an inert gas atmosphere such as Ar under reduced pressure. When the film formation reaction temperature (for example, about 1200° C.) is reached, the supply of the inert gas is stopped, and the material gas and carrier gas containing the components of the first silicon carbide polycrystalline films 220 a and 220 b are introduced into the film formation chamber 1010 . supply. The first silicon carbide polycrystalline films 220a and 220b can be formed on both surfaces of the heated support substrate 210 by the chemical reaction on the film formation target surface of the support substrate 210 and in the gas phase. As a result, as shown in FIG. 2A, a vapor deposition substrate 200 is obtained in which the first silicon carbide polycrystalline films 220a and 220b are formed on the support substrate 210. Next, as shown in FIG.

原料ガスとしては、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂを成膜させることができれば、特に限定されず、一般的に炭化ケイ素多結晶膜の成膜に使用されるＳｉ系原料ガス、Ｃ系原料ガスを用いることができる。例えば、Ｓｉ系原料ガスとしては、シラン（ＳｉＨ４）を用いることができるほか、モノクロロシラン（ＳｉＨ３Ｃｌ）、ジクロロシラン（ＳｉＨ２Ｃｌ２）、トリクロロシラン（ＳｉＨＣｌ３）、テトラクロロシラン（ＳｉＣｌ４）などのエッチング作用があるＣｌを含む塩素系Ｓｉ原料含有ガス（クロライド系原料）を用いることができる。Ｃ系原料ガスとしては、例えば、メタン（ＣＨ４）、プロパン（Ｃ３Ｈ８）、アセチレン（Ｃ２Ｈ２）等の炭化水素を用いることができる。上記のほか、トリクロロメチルシラン（ＣＨ３Ｃｌ３Ｓｉ）、トリクロロフェニルシラン（Ｃ６Ｈ５Ｃｌ３Ｓｉ）、ジクロロメチルシラン（ＣＨ４Ｃｌ２Ｓｉ）、ジクロロジメチルシラン（（ＣＨ３）２ＳｉＣｌ２）、クロロトリメチルシラン（（ＣＨ３）３ＳｉＣｌ）等のＳｉとＣとを両方含むガスも、原料ガスとして用いることができる。 The raw material gas is not particularly limited as long as it can form the first polycrystalline silicon carbide films 220a and 220b. A raw material gas can be used. For example, as the Si-based source gas, silane (SiH 4 ) can be used, as well as monochlorosilane (SiH 3 Cl), dichlorosilane (SiH 2 Cl 2 ), trichlorosilane (SiHCl 3 ), tetrachlorosilane (SiCl 4 ) can be used. Hydrocarbons such as methane (CH 4 ), propane (C 3 H 8 ), and acetylene (C 2 H 2 ) can be used as the C source gas. 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 ((CH 3 ) 2 SiCl 2 ), chlorotrimethylsilane ((CH 3 ) 3 SiCl), and other gases containing both Si and C can also be used as source gases.

また、キャリアガスとしては、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜を阻害することなく、原料ガスを支持基板２１０へ展開することができれば、一般的に使用されるキャリアガスを用いることができる。例えば、熱伝導率に優れ、炭化ケイ素に対してエッチング作用があるＨ２ガスをキャリアガスとして用いることができる。また、これら原料ガスおよびキャリアガスと同時に、第３のガスとして、不純物ドーピングガスを同時に供給することもできる。例えば、炭化ケイ素多結晶基板２０００の導電型をｎ型とする場合には窒素（Ｎ２）、ｐ型とする場合にはトリメチルアルミニウム（ＴＭＡ）を用いることができる。 As the carrier gas, a generally used carrier gas may be used as long as the source gas can be spread to the supporting substrate 210 without interfering with the formation of the first polycrystalline silicon carbide films 220a and 220b. can be done. For example, H 2 gas, which has excellent thermal conductivity and an etching effect on silicon carbide, can be used as a carrier gas. Also, an impurity doping gas can be supplied as a third gas at the same time as these raw material gas and carrier gas. For example, nitrogen (N 2 ) can be used when the conductivity type of the silicon carbide polycrystalline substrate 2000 is n-type, and trimethylaluminum (TMA) can be used when it is p-type.

第１炭化ケイ素多結晶膜２２０ａ、２２０ｂを成膜させる際には、上記のガスを適宜混合して供給する。また、所望の炭化ケイ素多結晶膜の性状に応じて、成膜工程の途中でガスの混合割合を変更してもよい。 When forming the first silicon carbide polycrystalline films 220a and 220b, the above gases are appropriately mixed and supplied. Further, the mixing ratio of the gases may be changed during the film forming process depending on the properties of the desired polycrystalline silicon carbide film.

また、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂは、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’として、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜する成膜工程の際の成膜対象となる。よって、炭化ケイ素多結晶基板２０００の安定した形状を得るために、成膜対象としてある程度の強度を有することが必要である。このことから、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の膜厚は、５０μｍ以上とする。 In addition, the first polycrystalline silicon carbide films 220a and 220b serve as the polycrystalline silicon carbide supporting substrates 220a' and 220b', and are the targets of film formation during the film forming process of forming the second polycrystalline silicon carbide films 230a and 230b. becomes. Therefore, in order to obtain a stable shape of the silicon carbide polycrystalline substrate 2000, it is necessary that the object to be film-formed has a certain degree of strength. For this reason, the film thickness of the silicon carbide polycrystalline support substrates 220a' and 220b' is set to 50 μm or more.

また、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂを厚くし過ぎると、結晶成長に伴うひずみが大きくなりやすく、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの成膜工程を経て、炭化ケイ素多結晶基板２０００を得たときに、デバイス等の製造に用いるときに問題となる反りが残存する可能性がある。このことから、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の厚さは、２５０μｍ以下とする。 In addition, if the first polycrystalline silicon carbide films 220a and 220b are made too thick, strain due to crystal growth tends to increase. When 2000 is obtained, there is a possibility that warpage that becomes a problem when used for manufacturing devices or the like remains. Accordingly, the thickness of the silicon carbide polycrystalline support substrates 220a' and 220b' is set to 250 μm or less.

次に、蒸着基板２００から、支持基板２１０の除去を行う。支持基板２１０として、黒鉛製の支持基板２１０を用いた場合には、蒸着基板２００を燃焼して、支持基板２１０を除去することができる。燃焼による支持基板２１０の除去工程は、例えば、二珪化モリブデン製のヒーターを備える燃焼炉等を用いることができる。蒸着基板２００を燃焼炉内に保持して、燃焼炉内にＯ２や空気等の酸化性ガスを供給しながら、常圧または減圧状態で、ヒーターにより燃焼炉内を数百度（例えば、８００℃程度）に加熱する。加熱により、支持基板２１０のみが燃焼して、図２（Ｂ）に示すように、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’が得られる。なお、図２（Ａ）、図２（Ｂ）は、第１炭化ケイ素多結晶膜２２０ａから炭化ケイ素多結晶支持基板２２０ａ’が得られ、第１炭化ケイ素多結晶膜２２０ｂから炭化ケイ素多結晶支持基板２２０ｂ’が得られることを示している。 Next, the support substrate 210 is removed from the vapor deposition substrate 200 . When the supporting substrate 210 made of graphite is used as the supporting substrate 210 , the supporting substrate 210 can be removed by burning the deposition substrate 200 . For the step of removing the support substrate 210 by combustion, for example, a combustion furnace equipped with a heater made of molybdenum disilicide can be used. While holding the vapor deposition substrate 200 in a combustion furnace and supplying oxidizing gas such as O 2 and air into the combustion furnace, the inside of the combustion furnace is heated to several hundred degrees (for example, 800 ° C.) by a heater under normal pressure or reduced pressure. degree). By heating, only the supporting substrate 210 is burned to obtain polycrystalline silicon carbide supporting substrates 220a' and 220b' as shown in FIG. 2(B). 2A and 2B, a silicon carbide polycrystalline support substrate 220a′ is obtained from the first silicon carbide polycrystalline film 220a, and a silicon carbide polycrystalline support substrate is obtained from the first silicon carbide polycrystalline film 220b. It shows that a substrate 220b' is obtained.

また、支持基板２１０として、ケイ素製の支持基板を用いた場合には、蒸着基板２００を硝フッ酸（硝酸とフッ化水素酸の混合酸）に浸漬して、ケイ素製の支持基板２１０のみを溶解することで、図２（Ｂ）に示すように、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’が得られる。 When a support substrate made of silicon is used as the support substrate 210, the vapor deposition substrate 200 is immersed in nitric hydrofluoric acid (mixed acid of nitric acid and hydrofluoric acid) to remove only the support substrate 210 made of silicon. By dissolving, silicon carbide polycrystalline support substrates 220a' and 220b' are obtained as shown in FIG. 2(B).

なお、支持基板２１０の全面が第１炭化ケイ素多結晶膜２２０ａ、２２０ｂで覆われた場合には、支持基板２１０を露出させるため、蒸着基板２００の外周端部を切断して支持基板２１０を露出させる切断工程を含んでもよい。 When the entire surface of the support substrate 210 is covered with the first silicon carbide polycrystalline films 220a and 220b, the support substrate 210 is exposed by cutting the outer peripheral edge of the vapor deposition substrate 200 to expose the support substrate 210. It may also include a cutting step to allow.

次に、成膜装置１０００の載置部１０７２に炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を載置して、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の成膜対象面に、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜する、成膜工程を行う。成膜工程における、成膜の手順、原料等は、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜と同様にして行うことができる。なお、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’はそれぞれを支持基板の代わりとなる成膜対象として用いることができる。 Next, the polycrystalline silicon carbide supporting substrates 220a′ and 220b′ are placed on the mounting portion 1072 of the film forming apparatus 1000, and the second film formation target surfaces of the polycrystalline silicon carbide supporting substrates 220a′ and 220b′ are coated with the second film-forming target surfaces. A film forming process is performed to form silicon carbide polycrystalline films 230a and 230b. The film forming procedure, raw materials, etc. in the film forming process can be performed in the same manner as in the film forming of the first silicon carbide polycrystalline films 220a and 220b. The silicon carbide polycrystalline support substrates 220a' and 220b' can each be used as a film formation target instead of the support substrate.

図２（Ｃ）は、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を成膜対象として成膜工程を行って得られた炭化ケイ素多結晶基板２０００を示す図である。図２（Ｃ）に示すように、成膜工程により、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の表面２２０ａ１、２２０ｂ１と、裏面２２０ａ２、２２０ｂ２の両面を成膜対象面として第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜させる。なお、得られた炭化ケイ素多結晶基板２０００において問題となる反りが発生することを抑制するために、成膜工程において成膜する第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの厚さは、７０μｍ以上とすることが好ましい。以上により、炭化ケイ素多結晶基板２０００が得られる。 FIG. 2(C) is a diagram showing a polycrystalline silicon carbide substrate 2000 obtained by performing a film forming process on polycrystalline silicon carbide supporting substrates 220a' and 220b'. As shown in FIG. 2(C), the second silicon carbide polycrystalline silicon carbide polycrystalline supporting substrates 220a′ and 220b′ are formed on both front surfaces 220a1 and 220b1 and back surfaces 220a2 and 220b2 of the silicon carbide polycrystalline support substrates 220a′ and 220b′, respectively. Crystal films 230a and 230b are formed. In addition, in order to suppress the occurrence of problematic warping in the obtained polycrystalline silicon carbide substrate 2000, the thickness of the second polycrystalline silicon carbide films 230a and 230b formed in the film forming process is set to 70 μm or more. It is preferable to As described above, silicon carbide polycrystalline substrate 2000 is obtained.

本実施形態の炭化ケイ素多結晶基板２０００の製造方法は、化学蒸着により支持基板２１０の成膜対象面に第１炭化ケイ素多結晶膜２２０ａ、２２０ｂを成膜させた後、支持基板２１０を除去して得られる膜厚が５０μｍ～２５０μｍの炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の成膜対象面に、化学蒸着により第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜する成膜工程を含む。第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの膜厚が大きくなるにしたがって、支持基板２１０から遠い位置ほど、蒸着する炭化ケイ素の結晶粒の大きさが大きくなる。このことから、一度の成膜工程において成膜する膜厚を大きくすると、大きな反りが発生することがある。しかしながら、本実施形態の方法であれば、まず５０μｍ～２５０μｍの炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を形成し、それにさらに第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜することで、大きな反りの発生を抑制することができる。以上のことから、本実施形態の方法により、炭化ケイ素多結晶基板２０００に発生し得る、デバイス等の製造工程で問題となる反り量を低減することができる。 In the method for manufacturing a polycrystalline silicon carbide substrate 2000 of the present embodiment, the first polycrystalline silicon carbide films 220a and 220b are formed on the film formation target surface of the support substrate 210 by chemical vapor deposition, and then the support substrate 210 is removed. a film formation step of forming second silicon carbide polycrystalline films 230a and 230b by chemical vapor deposition on the film formation target surfaces of the silicon carbide polycrystalline support substrates 220a′ and 220b′ having a film thickness of 50 μm to 250 μm obtained by . As the film thickness of the first polycrystalline silicon carbide films 220a and 220b increases, the size of crystal grains of the deposited silicon carbide increases with increasing distance from the support substrate 210. FIG. For this reason, when the film thickness to be formed in one film forming process is increased, a large warp may occur. However, according to the method of the present embodiment, silicon carbide polycrystalline support substrates 220a' and 220b' having a thickness of 50 μm to 250 μm are first formed, and then second silicon carbide polycrystalline films 230a and 230b are formed thereon. It is possible to suppress the occurrence of large warpage. As described above, according to the method of the present embodiment, it is possible to reduce the amount of warpage that may occur in the polycrystalline silicon carbide substrate 2000 and which poses a problem in the manufacturing process of devices and the like.

また、成膜工程において、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の表面２２０ａ１、２２０ｂ１と、裏面２２０ａ２、２２０ｂ２の両面に、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜することから、片面のみに成膜する場合に比べて、成膜工程で形成する第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの厚さを半分にすることができる。よって、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の両面に成膜することで、炭化ケイ素多結晶基板２０００に発生し得る反り量をより少なくすることができる。 In addition, since the second polycrystalline silicon carbide films 230a and 230b are formed on both the front surfaces 220a1 and 220b1 and the back surfaces 220a2 and 220b2 of the silicon carbide polycrystalline support substrates 220a' and 220b' in the film forming process, The thickness of the second silicon carbide polycrystalline films 230a and 230b formed in the film formation process can be halved compared to the case of forming the film only on one side. Therefore, by forming films on both surfaces of the silicon carbide polycrystalline support substrates 220a' and 220b', the amount of warpage that may occur in the silicon carbide polycrystalline substrate 2000 can be further reduced.

なお、本発明は、前述した実施形態に限定されるものではなく、本発明の目的が達成できる他の工程等を含み、以下に示すような変形等も本発明に含まれる。 It should be noted that the present invention is not limited to the above-described embodiments, but includes other processes and the like that can achieve the object of the present invention, and the following modifications and the like are also included in the present invention.

第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜時において、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの原料ガスの噴出位置（ガス導入口１０２０）からの噴出方向と、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂが成膜される支持基板２１０の成膜対象面（表面２１０ａ、裏面２１０ｂ）（図１）と、が垂直であり、成膜工程において、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの原料ガスの噴出位置（ガス導入口１０２０）からの噴出方向と、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂが成膜される炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の成膜対象面と、が垂直であり、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の成膜対象面が、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜時に、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの原料ガスの噴出位置（ガス導入口１０２０）と対向する第１面（炭化ケイ素多結晶支持基板２２０ａ’の裏面２２０ａ２、炭化ケイ素多結晶支持基板２２０ｂ’の表面２２０ｂ１）と、前記第１面の裏側の面となる第２面（炭化ケイ素多結晶支持基板２２０ａ’の表面２２０ａ１、炭化ケイ素多結晶支持基板２２０ｂ’の裏面２２０ｂ２）と、からなり、第２面を、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの原料ガスの噴出位置（ガス導入口１０２０）に向けて、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜させてもよい（図３）。 When forming the first polycrystalline silicon carbide films 220a and 220b, the direction of ejection from the ejection position (gas inlet 1020) of the raw material gas for the first polycrystalline silicon carbide films 220a and 220b and the direction of ejection of the first polycrystalline silicon carbide films 220a and 220b The film formation target surfaces (front surface 210a, back surface 210b) (FIG. 1) of the support substrate 210 on which the films 220a and 220b are formed are perpendicular to each other, and the second silicon carbide polycrystalline films 230a and 230b are formed in the film formation process. and the film formation target surfaces of the silicon carbide polycrystalline support substrates 220a′ and 220b′ on which the second polycrystalline silicon carbide films 230a and 230b are formed. are perpendicular to each other, and the film-forming target surfaces of the polycrystalline silicon carbide supporting substrates 220a' and 220b' are aligned with the surfaces of the first polycrystalline silicon carbide films 220a and 220b when the first polycrystalline silicon carbide films 220a and 220b are formed. A first surface (back surface 220a2 of polycrystalline silicon carbide support substrate 220a′, front surface 220b1 of polycrystalline silicon carbide support substrate 220b′) facing the source gas ejection position (gas inlet 1020), and the back surface of the first surface (front surface 220a1 of polycrystalline silicon carbide support substrate 220a′, back surface 220b2 of polycrystalline silicon carbide support substrate 220b′), which is the second surface of polycrystalline silicon carbide film 230a. , 230b (gas introduction port 1020), the second silicon carbide polycrystalline films 230a and 230b may be deposited (FIG. 3).

前述した実施形態においては、図１の矢印で示すように、原料ガス等のガスは、ガス導入口１０２０から鉛直方向に噴出され、水平方向にも拡散しながら、成膜室１０１０の下方から上方に向かって流動する。また、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂが成膜される支持基板２１０は、成膜対象面（表面２１０ａ、裏面２１０ｂ）が水平になるように、基板ホルダー１０７０に載置されている。すなわち、前述した実施形態においては、原料ガスの噴出位置（ガス導入口１０２０）からの原料ガスの噴出方向と、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂが成膜される支持基板２１０の成膜対象面（表面２１０ａ、裏面２１０ｂ）と、が垂直である。このとき、ガス導入口１０２０からの下方から上方へのガスの流れにより、成膜された第１炭化ケイ素多結晶膜２２０ａ、２２０ｂにひずみが生じる場合がある。そこで、成膜条件や所望の炭化ケイ素多結晶基板２０００の性能に応じて、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜させる成膜工程おいて、生じたひずみを相殺するように炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を配置してもよい。 In the above-described embodiment, as indicated by the arrow in FIG. 1, the gas such as the raw material gas is ejected vertically from the gas inlet 1020 and spreads horizontally from the bottom to the top of the film forming chamber 1010. flow towards The support substrate 210 on which the first silicon carbide polycrystalline films 220a and 220b are to be formed is placed on the substrate holder 1070 so that the film formation target surfaces (front surface 210a and rear surface 210b) are horizontal. That is, in the above-described embodiment, the ejection direction of the source gas from the source gas ejection position (gas introduction port 1020) and the film formation of the support substrate 210 on which the first polycrystalline silicon carbide films 220a and 220b are formed. are perpendicular to the target surface (front surface 210a, back surface 210b). At this time, the upward gas flow from the gas inlet 1020 may cause strain in the formed first silicon carbide polycrystalline films 220a and 220b. Therefore, in the film forming step of forming the second polycrystalline silicon carbide films 230a and 230b, silicon carbide is added so as to offset the generated strain according to the film forming conditions and the desired performance of the polycrystalline silicon carbide substrate 2000. Polycrystalline support substrates 220a', 220b' may be arranged.

前述した実施形態においては、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂは、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の両面（表面２２０ａ１、２２０ｂ１と、裏面２２０ａ２、２２０ｂ２）に成膜され、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’は、成膜対象面（表面２２０ａ１、２２０ｂ１と、裏面２２０ａ２、２２０ｂ２）が水平になるように、基板ホルダー１０７０に載置されている。よって、成膜工程において、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの原料ガスの噴出位置（ガス導入口１０２０）からの原料ガスの噴出方向と、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂが成膜される炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の成膜対象面（表面２２０ａ１、２２０ｂ１と、裏面２２０ａ２、２２０ｂ２）と、が垂直である。また、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’の成膜対象面は、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜時に、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの原料ガスの噴出位置（ガス導入口１０２０）と対向する第１面（炭化ケイ素多結晶支持基板２２０ａ’の裏面２２０ａ２、炭化ケイ素多結晶支持基板２２０ｂ’の表面２２０ｂ１）と、第１面の裏側の面となる第２面（炭化ケイ素多結晶支持基板２２０ａ’の表面２２０ａ１、炭化ケイ素多結晶支持基板２２０ｂ’の裏面２２０ｂ２）と、からなる。第１炭化ケイ素多結晶膜２２０ａ、２２０ｂに生じたときに、このひずみを相殺するには、例えば、図３に示すように、成膜工程において、第２面（炭化ケイ素多結晶支持基板２２０ａ’の表面２２０ａ１、炭化ケイ素多結晶支持基板２２０ｂ’の裏面２２０ｂ２）を、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの原料ガスの噴出位置（ガス導入口１０２０）に向けて、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜させればよい。これにより、例えば炭化ケイ素多結晶支持基板２２０ａ’においては、第１炭化ケイ素多結晶膜２２０ａの成膜時には、ガスの流動方向が裏面２２０ａ２から表面２２０ａ１の方向であったのに対して、第２炭化ケイ素多結晶膜２３０ａの成膜時には、ガスの流動方向が表面２２０ａ１から裏面２２０ａ２の方向となる。すなわち、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’に対して、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’となる第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜時と、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’への第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの成膜時とで、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’への原料ガス等のガスの流動方向が異なる。このように、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜時と、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの成膜時とで、炭化ケイ素多結晶支持基板２２０ａ’（第１炭化ケイ素多結晶膜２２０ａ）に対する原料ガスの流動方向に偏りが生じないようにすることで、ガスの流れにより生じうる炭化ケイ素多結晶膜のひずみを相殺して、炭化ケイ素多結晶基板２０００に発生し得る反りの反り量を少なくすることができる。 In the above-described embodiment, the second silicon carbide polycrystalline films 230a, 230b are formed on both surfaces (front surfaces 220a1, 220b1 and back surfaces 220a2, 220b2) of the silicon carbide polycrystalline support substrates 220a′, 220b′, and carbonized. The silicon polycrystalline support substrates 220a' and 220b' are mounted on the substrate holder 1070 so that the film formation target surfaces (surfaces 220a1 and 220b1 and back surfaces 220a2 and 220b2) are horizontal. Therefore, in the film forming process, the ejection direction of the raw material gas from the ejection position (gas inlet 1020) of the raw material gas of the second silicon carbide polycrystalline films 230a and 230b and the second silicon carbide polycrystalline films 230a and 230b are formed. The film formation target surfaces (surfaces 220a1 and 220b1 and back surfaces 220a2 and 220b2) of the silicon carbide polycrystalline support substrates 220a' and 220b' to be filmed are perpendicular to each other. In addition, the film-forming target surfaces of the polycrystalline silicon carbide supporting substrates 220a′ and 220b′ are subjected to ejection of raw material gas for the first polycrystalline silicon carbide films 220a and 220b when the first polycrystalline silicon carbide films 220a and 220b are formed. A first surface (back surface 220a2 of polycrystalline silicon carbide support substrate 220a′, front surface 220b1 of polycrystalline silicon carbide support substrate 220b′) facing the position (gas inlet 1020) It consists of two surfaces (front surface 220a1 of polycrystalline silicon carbide support substrate 220a′ and back surface 220b2 of polycrystalline silicon carbide support substrate 220b′). In order to cancel the strain when it occurs in the first polycrystalline silicon carbide films 220a and 220b, for example, as shown in FIG. surface 220a1 of the polycrystalline silicon carbide support substrate 220b' and the back surface 220b2 of the polycrystalline silicon carbide substrate 220b') are directed toward the ejection position (gas inlet 1020) of the raw material gas for the second polycrystalline silicon carbide films 230a and 230b, and the second polycrystalline silicon carbide Films 230a and 230b may be deposited. As a result, for example, in the silicon carbide polycrystalline support substrate 220a′, the gas flow direction was from the back surface 220a2 to the front surface 220a1 when the first polycrystalline silicon carbide film 220a was formed. When the silicon carbide polycrystalline film 230a is formed, the direction of gas flow is from the front surface 220a1 to the rear surface 220a2. That is, when forming the first polycrystalline silicon carbide films 220a and 220b to be the polycrystalline silicon carbide supporting substrates 220a′ and 220b′ on the polycrystalline silicon carbide supporting substrates 220a′ and 220b′, The flow directions of gases such as raw material gases to the polycrystalline silicon carbide supporting substrates 220a' and 220b' are different from when the second polycrystalline silicon carbide films 230a and 230b are formed on the supporting substrates 220a' and 220b'. In this way, the silicon carbide polycrystalline supporting substrate 220a′ (the first silicon carbide polycrystalline film) is formed during the deposition of the first polycrystalline silicon carbide films 220a and 220b and during the deposition of the second polycrystalline silicon carbide films 230a and 230b. By preventing bias in the flow direction of the raw material gas with respect to the polycrystalline film 220a), the distortion of the polycrystalline silicon carbide film that may be caused by the flow of the gas is offset, and the distortion that may occur in the polycrystalline silicon carbide substrate 2000 is offset. The amount of warpage can be reduced.

また、前述した実施形態においては、炭化ケイ素多結晶支持基板２２０ａ’の両面に第２炭化ケイ素多結晶膜２３０ａ、２３０ｂを成膜する例を示したが、片面に成膜してもよい。すなわち、例えば、炭化ケイ素多結晶支持基板２２０ａ’の片面全体が接地する台座等に炭化ケイ素多結晶支持基板２２０ａ’を載置して、炭化ケイ素多結晶支持基板２２０ａ’の前記片面と反対側の面のみに炭化ケイ素多結晶膜を成膜してもよい。 Further, in the above-described embodiment, an example of forming the second polycrystalline silicon carbide films 230a and 230b on both sides of the polycrystalline silicon carbide support substrate 220a' was shown, but they may be formed on one side. That is, for example, the polycrystalline silicon carbide supporting substrate 220a′ is placed on a pedestal or the like on which the entire one side of the polycrystalline silicon carbide supporting substrate 220a′ is grounded, and the one side and the opposite side of the polycrystalline silicon carbide supporting substrate 220a′ are grounded. A silicon carbide polycrystalline film may be deposited only on the surface.

また、前述した実施形態においては、第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜と、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの成膜を一連の工程で行ったが、蒸着基板２００または炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を中間体として製造しておき、別の製造工程として第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの成膜工程を行ってもよい。また、蒸着基板２００、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を購入等して入手し、これに成膜工程を行ってもよい。 Further, in the above-described embodiment, the formation of the first polycrystalline silicon carbide films 220a and 220b and the formation of the second polycrystalline silicon carbide films 230a and 230b are performed in a series of steps. The polycrystalline silicon carbide supporting substrates 220a' and 220b' may be manufactured as intermediates, and the second polycrystalline silicon carbide films 230a and 230b may be formed as a separate manufacturing process. Alternatively, the vapor deposition substrate 200 and the silicon carbide polycrystalline support substrates 220a' and 220b' may be purchased and obtained, and the film formation process may be performed on them.

以下、本発明の実施例および比較例によって、本発明をさらに詳細に説明するが、本発明は、これらの実施例によって何ら限定されることはない。 EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited by these Examples.

本実施例においては、前述した実施形態の成膜装置１０００を用いて、炭化ケイ素多結晶基板を製造した。 In this example, a polycrystalline silicon carbide substrate was manufactured using the film forming apparatus 1000 of the above-described embodiment.

（実施例１）
まず、支持基板２１０に第１炭化ケイ素多結晶膜２２０ａ、２２０ｂを成膜させた。なお、本実施例においては、この工程を「第一工程」と称する。支持基板として、直径１５０ｍｍ、厚さ５０μｍの黒鉛基板を使用した。支持基板２１０を成膜装置１０００の載置部１０７２に載置して成膜室１０１０内を不図示の排気ポンプにより真空引きをした後、１３５０℃まで加熱した。原料ガスとして、ＳｉＣｌ４、ＣＨ４を用い、キャリアガスとしてＨ２を用い、不純物ドーピングガスとしてＮ２を用いた。第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜は、ＳｉＣｌ４：ＣＨ４：Ｈ２：Ｎ２＝１：１：１０：１０の比率で上記ガスを混合して成膜室１０１０内に供給し、１００分間の成膜を実施した。以上により、支持基板２１０上に厚さ５０μｍの第１炭化ケイ素多結晶膜２２０ａ、２２０ｂが成膜した蒸着基板２００を得た。 (Example 1)
First, first silicon carbide polycrystalline films 220 a and 220 b were formed on the support substrate 210 . In addition, in this embodiment, this step is referred to as a "first step". A graphite substrate having a diameter of 150 mm and a thickness of 50 μm was used as a support substrate. After the supporting substrate 210 was placed on the mounting portion 1072 of the film forming apparatus 1000 and the inside of the film forming chamber 1010 was evacuated by an exhaust pump (not shown), the chamber was heated to 1350.degree. SiCl 4 and CH 4 were used as raw material gases, H 2 was used as carrier gas, and N 2 was used as impurity doping gas. The first silicon carbide polycrystalline films 220a and 220b are formed by mixing the above gases at a ratio of SiCl 4 :CH 4 :H 2 :N 2 =1:1:10:10 and supplying them into the film forming chamber 1010 . Then, film formation was performed for 100 minutes. As described above, a vapor deposition substrate 200 was obtained in which the first silicon carbide polycrystalline films 220a and 220b having a thickness of 50 μm were formed on the support substrate 210 .

次に、二珪化モリブデン製のヒーターを備える燃焼炉を用いて、蒸着基板２００を大気環境下、８００℃で１００時間燃焼して、支持基板２１０を除去して、炭化ケイ素多結晶支持基板２２０ａ’、２２０ｂ’を得た。 Next, using a combustion furnace equipped with a heater made of molybdenum disilicide, the vapor deposition substrate 200 is burned at 800° C. for 100 hours in an atmospheric environment to remove the support substrate 210 and obtain a polycrystalline silicon carbide support substrate 220a′. , 220b′.

次に、炭化ケイ素多結晶支持基板２２０ａ’を用いて、第２炭化ケイ素多結晶膜２３０ａ、２３０ｂの成膜工程を行った。なお、本実施例においては、成膜工程を「第二工程」と称する。第１炭化ケイ素多結晶膜２２０ａ、２２０ｂの成膜と同様に、成膜装置１０００を用いて、ＳｉＣｌ４：ＣＨ４：Ｈ２：Ｎ２＝１：１：１０：１０の比率で上記ガスを混合して成膜室１０１０内に供給し、１３５０℃で３００分間の成膜を実施した。このとき、第１炭化ケイ素多結晶膜２２０ａの成膜時にガス導入口１０２０に対向する面である、炭化ケイ素多結晶支持基板２２０ａ’の裏面２２０ａ２をガス導入口１０２０に向けて、載置部１０７２に載置した。以上により、炭化ケイ素多結晶支持基板２２０ａ’の両面にそれぞれ厚さ１５０μｍの第２炭化ケイ素多結晶膜２３０ａ、２３０ｂが成膜した、厚さ３５０μｍの炭化ケイ素多結晶基板２０００を得た。 Next, using the polycrystalline silicon carbide support substrate 220a′, a step of forming second polycrystalline silicon carbide films 230a and 230b was performed. In addition, in the present embodiment, the film forming process is referred to as a "second process". Similar to the deposition of the first silicon carbide polycrystalline films 220a and 220b, the deposition apparatus 1000 was used to deposit the above gases at a ratio of SiCl4 : CH4 : H2 : N2 =1:1:10:10. The mixture was supplied into the film forming chamber 1010, and film formation was performed at 1350° C. for 300 minutes. At this time, the rear surface 220a2 of the polycrystalline silicon carbide support substrate 220a′, which is the surface facing the gas inlet 1020 during the deposition of the first polycrystalline silicon carbide film 220a, is directed toward the gas inlet 1020, and the mounting portion 1072 is placed. placed on. As a result, a polycrystalline silicon carbide substrate 2000 having a thickness of 350 μm was obtained, in which the second polycrystalline silicon carbide films 230a and 230b having a thickness of 150 μm were formed on both surfaces of the polycrystalline silicon carbide supporting substrate 220a′.

炭化ケイ素多結晶支持基板２２０ａ’、炭化ケイ素多結晶基板２０００の反りについて、炭化ケイ素多結晶基板の成膜対象面の中心線上を斜入射型光学測定器により測定し、得られた測定値の最大値と最小値との差を反り量とした。測定は５点とし、中心、円周端部、および中心と円周端部との間にあり、中心からの距離と円周端部からの距離が同じ地点について、測定した。反り量が、５０μｍより大きいとき、製造した炭化ケイ素多結晶基板２０００について、デバイス等の製造工程で問題の生じ得る反りが有ると判定した。結果を表１に示した。なお、表１には、炭化ケイ素多結晶支持基板２２０ａ’の反り量は第一工程後の反り量として、炭化ケイ素多結晶基板２０００の反り量は第二工程後の反り量として、示している。 Regarding the warpage of the silicon carbide polycrystalline support substrate 220a′ and the silicon carbide polycrystalline substrate 2000, the center line of the film formation target surface of the silicon carbide polycrystalline substrate was measured with an oblique incidence type optical measuring instrument, and the maximum of the obtained measurement values was The difference between the value and the minimum value was defined as the amount of warpage. Five points were measured: the center, the edge of the circumference, and the point between the center and the edge of the circumference, the distance from the center being the same as the distance from the edge of the circumference. When the amount of warpage was greater than 50 μm, it was determined that the manufactured polycrystalline silicon carbide substrate 2000 had warpage that could cause problems in the manufacturing process of devices and the like. Table 1 shows the results. In Table 1, the amount of warpage of the polycrystalline silicon carbide supporting substrate 220a' is shown as the amount of warpage after the first step, and the amount of warpage of the polycrystalline silicon carbide substrate 2000 is shown as the amount of warpage after the second step. .

（実施例２、実施例３、比較例１、比較例２）
実施例２、実施例３、比較例１、比較例２として、第一工程、第二工程の成膜時間を実施例１とは変えて、異なる膜厚の炭化ケイ素多結晶膜を得たこと以外は、実施例１と同じ条件で炭化ケイ素多結晶基板の製造を行った。比較例１は、第二工程の時間を０として、第一工程のみにより厚さ３５０μｍの炭化ケイ素多結晶基板の膜厚を得た。実施例２、実施例３、比較例１、比較例２においては、実施例１と同じ厚さ３５０μｍの炭化ケイ素多結晶基板を製造した。成膜時間の条件、得られた膜厚は、表１に示した。第一工程、第二工程で得られた炭化ケイ素多結晶基板について、実施例１と同様に、反り量の確認を行った。 (Example 2, Example 3, Comparative Example 1, Comparative Example 2)
As Example 2, Example 3, Comparative Example 1, and Comparative Example 2, the film formation times of the first step and the second step were changed from Example 1 to obtain silicon carbide polycrystalline films with different thicknesses. A silicon carbide polycrystalline substrate was manufactured under the same conditions as in Example 1, except for the above. In Comparative Example 1, the time of the second step was set to 0, and a silicon carbide polycrystalline substrate having a thickness of 350 μm was obtained only by the first step. In Example 2, Example 3, Comparative Example 1, and Comparative Example 2, polycrystalline silicon carbide substrates having a thickness of 350 μm, which is the same as in Example 1, were manufactured. Table 1 shows the film formation time conditions and the obtained film thickness. For the silicon carbide polycrystalline substrates obtained in the first step and the second step, the amount of warpage was confirmed in the same manner as in Example 1.

（実施例４）
実施例４として、炭化ケイ素多結晶支持基板２２０ａ’を用いた成膜工程において、第１炭化ケイ素多結晶膜２２０ａの成膜時に、ガス導入口１０２０と対向しない面（表面２２０ａ１）をガス導入口１０２０に向けて、載置部１０７２に載置したこと以外は、実施例３と同じ条件で炭化ケイ素多結晶基板の製造を行った。第一工程、第二工程で得られた炭化ケイ素多結晶基板について、実施例１と同様に、反り量の確認を行った。 (Example 4)
As Example 4, in the film forming process using the polycrystalline silicon carbide supporting substrate 220a′, the surface (surface 220a1) not facing the gas inlet 1020 was formed with the gas inlet when forming the first polycrystalline silicon carbide film 220a. A silicon carbide polycrystalline substrate was manufactured under the same conditions as in Example 3, except that it was placed on the placing portion 1072 toward 1020 . For the silicon carbide polycrystalline substrates obtained in the first step and the second step, the amount of warpage was confirmed in the same manner as in Example 1.

（評価結果）

Figure 0007338193000001
(Evaluation results)
Figure 0007338193000001

反り量を測定した結果、実施例１～実施例４の炭化ケイ素多結晶基板２０００において、第二工程の炭化ケイ素多結晶基板の反り量が５０μｍ以内となり、デバイス等の製造工程において問題の生じ得る反りは確認されなかった。第一工程の膜厚を大きくした比較例１、２においては、炭化ケイ素多結晶基板の反り量が大きくなり、問題の生じ得る反りが確認された。また、比較例２においては、第一工程での反り量よりも第二工程での反り量の方が小さくなったが、５０μｍ以下とはならず、問題の生じ得る反りが残存した。 As a result of measuring the amount of warpage, in the polycrystalline silicon carbide substrates 2000 of Examples 1 to 4, the amount of warpage of the polycrystalline silicon carbide substrate in the second step was within 50 μm, which may cause problems in the manufacturing process of devices and the like. No warpage was confirmed. In Comparative Examples 1 and 2 in which the film thickness in the first step was increased, the amount of warpage of the polycrystalline silicon carbide substrate was increased, and warpage that could cause problems was confirmed. In Comparative Example 2, the amount of warpage in the second step was smaller than the amount of warpage in the first step, but it did not become 50 μm or less, and warpage that could cause problems remained.

また、炭化ケイ素多結晶支持基板２２０ａ’の凹状に形成された裏面２２０ａ２をガス導入口１０２０に向けて載置した実施例４においては、実施例３に比べて第二工程で得られた炭化ケイ素多結晶基板２０００の反り量が小さくなった。このことから、第一工程で反りが発生した場合、炭化ケイ素多結晶基板の凹状に形成された面をガス導入口１０２０に向けて、原料ガスに触れやすくすることが、製造された炭化ケイ素多結晶基板に発生し得る反り量の抑制により効果的であることが示された。 In addition, in Example 4, in which the concave back surface 220a2 of the silicon carbide polycrystalline support substrate 220a′ was placed facing the gas inlet 1020, the silicon carbide obtained in the second step compared to Example 3. The amount of warpage of the polycrystalline substrate 2000 is reduced. For this reason, when warping occurs in the first step, the concave surface of the polycrystalline silicon carbide substrate should face the gas inlet 1020 to make it easier to come into contact with the raw material gas. It was shown to be more effective in suppressing the amount of warpage that can occur in the crystal substrate.

本発明の例示的態様である実施例１～実施例４により、炭化ケイ素多結晶基板の製造において、製造された炭化ケイ素多結晶基板に発生し得る反り量を低減できることが示された。 Examples 1 to 4, which are exemplary embodiments of the present invention, show that the amount of warpage that can occur in the manufactured polycrystalline silicon carbide substrate can be reduced in manufacturing the polycrystalline silicon carbide substrate.

２０００ 炭化ケイ素多結晶基板
２２０ａ、２２０ｂ 第１炭化ケイ素多結晶膜
２３０ａ、２３０ｂ 第２炭化ケイ素多結晶膜
２２０ａ’、２２０ｂ’ 炭化ケイ素多結晶支持基板
２１０ 支持基板
２２０ａ２、２２０ｂ１ 第１面
２２０ａ１、２２０ｂ２ 第２面
１０２０ ガス導入口（原料ガスの噴出位置） 2000 Silicon carbide polycrystalline substrates 220a, 220b First silicon carbide polycrystalline films 230a, 230b Second silicon carbide polycrystalline films 220a', 220b' Silicon carbide polycrystalline support substrate 210 Support substrates 220a2, 220b1 First surfaces 220a1, 220b2 2nd side 1020 Gas introduction port (source gas ejection position)

Claims (3)

化学蒸着により支持基板の成膜対象面に第１炭化ケイ素多結晶膜を成膜させた後、前記支持基板を除去して得られる、膜厚が５０μｍ～２５０μｍの炭化ケイ素多結晶支持基板の成膜対象面に、化学蒸着により第２炭化ケイ素多結晶膜を成膜する成膜工程を含み、
前記第１炭化ケイ素多結晶膜の成膜時において、
前記第１炭化ケイ素多結晶膜の原料ガスの噴出位置からの噴出方向と、前記支持基板の成膜対象面と、が垂直であり、
前記成膜工程において、
前記第２炭化ケイ素多結晶膜の原料ガスの噴出位置からの噴出方向と、前記炭化ケイ素多結晶支持基板の成膜対象面と、が垂直であり、
前記炭化ケイ素多結晶支持基板の前記成膜対象面が、前記第１炭化ケイ素多結晶膜の成膜時に、前記第１炭化ケイ素多結晶膜の前記原料ガスの噴出位置と対向する第１面と、前記第１面の裏側の面となる第２面と、からなり、
前記第２面を、前記第２炭化ケイ素多結晶膜の原料ガスの噴出位置に向けて、前記第１面と前記第２面に同じ厚さの前記第２炭化ケイ素多結晶膜を成膜させる、前記成膜工程後の反り量が４０μｍ以内である、厚さが３００μｍ～７００μｍの炭化ケイ素多結晶基板の製造方法。 A polycrystalline silicon carbide supporting substrate having a film thickness of 50 μm to 250 μm is obtained by forming a first polycrystalline silicon carbide film on a film-forming target surface of a supporting substrate by chemical vapor deposition and then removing the supporting substrate. including a film forming step of forming a second silicon carbide polycrystalline film on the film target surface by chemical vapor deposition;
At the time of forming the first silicon carbide polycrystalline film,
the ejection direction from the ejection position of the raw material gas for the first silicon carbide polycrystalline film is perpendicular to the film formation target surface of the support substrate;
In the film forming step,
the ejection direction from the ejection position of the raw material gas for the second polycrystalline silicon carbide film is perpendicular to the film formation target surface of the polycrystalline silicon carbide support substrate;
The film formation target surface of the polycrystalline silicon carbide support substrate is a first surface that faces the injection position of the raw material gas of the first polycrystalline silicon carbide film during the film formation of the first polycrystalline silicon carbide film. , and a second surface that is the surface on the back side of the first surface,
The second silicon carbide polycrystalline film having the same thickness is formed on the first surface and the second surface with the second surface facing the injection position of the raw material gas of the second silicon carbide polycrystalline film. and a method for producing a polycrystalline silicon carbide substrate having a thickness of 300 μm to 700 μm, wherein the amount of warp after the film formation step is within 40 μm . 前記成膜工程で成膜する前記第２炭化ケイ素多結晶膜の厚さが、７０μｍ以上である、請求項１に記載の炭化ケイ素多結晶基板の製造方法。 2. The method for manufacturing a polycrystalline silicon carbide substrate according to claim 1, wherein the thickness of said second polycrystalline silicon carbide film formed in said film forming step is 70 [mu]m or more. 前記成膜工程において、前記炭化ケイ素多結晶支持基板の両面に、前記第２炭化ケイ素多結晶膜を成膜する、請求項１または２に記載の炭化ケイ素多結晶基板の製造方法。 3. The method for producing a polycrystalline silicon carbide substrate according to claim 1, wherein in said film forming step, said second polycrystalline silicon carbide films are formed on both surfaces of said polycrystalline silicon carbide supporting substrate.
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