JP2009041060A - Method for producing CVD-SiC - Google Patents

Abstract

An object of the present invention is to provide a CVD-SiC manufacturing method in which SiC is formed on the entire surface of a substrate without causing defects such as cracks, and a support can be integrated with the formed SiC film.
[Structure] In a method of placing a base material on a base material holding jig via a support tool that contacts the base material, and forming a SiC film on the base material surface by a CVD reaction, the support tool is obtained by the CVD reaction. It is formed from the formed SiC film.
[Selection figure] None

Description

  The present invention relates to a CVD-SiC manufacturing method in which a SiC film is formed by CVD (chemical vapor deposition) on a base material such as graphite material, carbon fiber reinforced carbon composite material, sintered SiC, and Si impregnated sintered SiC. .

  For example, a SiC-coated graphite material in which a SiC film is formed on the surface of a graphite substrate by CVD is excellent in non-contamination because a high-purity SiC film is applied to the surface, and also has a thermal shock resistance against rapid heating and rapid cooling. With good chemical stability such as oxidation resistance and chemical resistance, various heat treatment members in semiconductor manufacturing, such as susceptor, liner tube, process tube, wafer boat, single crystal pulling device member In addition, it can be used at higher temperatures than Si, sintered SiC, etc., so it is expected to be used as an etching electrode as an etching member, a focus ring, a holder for holding a Si wafer, etc. Each semiconductor manufacturing equipment maker is proceeding with evaluations toward practical use.

  Conventionally, the film formation by the CVD method is a method of forming a base material made of graphite or the like on which a film is to be formed on a base material holder at the upper part of a rotating shaft in a CVD reaction vessel, a graphite pin, a graphite pin on which an SiC film is formed, It is carried out by a method in which it is placed through a support such as a bar, and a raw material gas is supplied while rotating the substrate, and vapor deposition is performed by a CVD reaction.

  Unlike susceptors with SiC coatings formed on graphite materials, members directly used for Si wafer processing, such as etching electrodes, focus rings, and holders that hold Si wafers, must be high-purity SiC films. In addition, since the required film thickness is 10 times (mm order) or more, after the reaction for a long time, the substrate is removed to obtain the target SiC single film.

  In the film formation by the CVD method, it is necessary to form SiC on the entire surface of the base material. However, in the conventional method described above, the portion of the base material surface where the support is in contact is a raw material. Since the gas cannot enter, there is a disadvantage that the SiC film is not formed.

  In order to solve this drawback, an SiC plate is embedded in the base material, or the SiC plate is attached to the base material with an adhesive made of a mixture of a thermosetting resin and graphite, and is supported on the portion of the SiC plate. A method of contacting and supporting the tool has been proposed (see Patent Document 1), but this method requires precise processing of the SiC plate and the SiC plate embedded portion, and adhesion and hardening even when using an adhesive. In order to obtain a SiC film that is thicker than anything else, it is necessary to perform treatment for several times for a long time. In the process of thickening a SiC film once formed, such a method is used. It is practically impossible to adopt it.

  It has also been proposed to use a graphite material having a three-dimensional network structure in which an SiC film is formed as a support (see Patent Document 2), and it is also proposed to use a columnar graphite material in which an SiC film is formed. (See Patent Document 3). In these methods, when a relatively thin SiC film is formed on the substrate, the SiC film is formed on the entire surface of the substrate in a pseudo manner by leaving the previously formed SiC film on the support.

However, in these methods, when forming a thick SiC film, the SiC film is not formed on the base material supported by the support, so the balance of internal stress of the SiC film itself is lost, A strong warping force is applied to the SiC film, causing cracking or destruction. In addition, the support is only embedded with graphite or the like, and an SiC film having a desired thickness is not formed. Therefore, it must be removed for use as a product, and the yield is poor.
JP 2000-129444 A JP 2004-176140 A JP-A-2005-213571

  In order to obtain a thick SiC film without causing cracks or the like, it is possible to use the base film surface in an area where the SiC film is not formed as much as possible and to integrate with the SiC film in consideration of the product yield. It is required to use a support.

  In the present invention, based on the conventional CVD-SiC manufacturing method, in order to satisfy the above-described requirements, tests and examinations were performed on the material and shape of a support that abuts against the substrate and directly supports the description. As a result, the purpose of the CVD is such that SiC is formed on the entire surface of the substrate without causing defects such as cracks, and the support can be integrated with the formed SiC film. The object is to provide a method for producing SiC.

  In order to achieve the above object, a CVD-SiC manufacturing method according to claim 1 is configured such that a base material is placed on a base material holding jig via a support tool that comes into contact with the base material, and the base material surface is subjected to a CVD reaction. In the method of forming a SiC film, the support is formed of a SiC film obtained by a CVD reaction.

  The method for producing CVD-SiC according to claim 2 is characterized in that, in claim 1, the SiC film formed on the support is an SiC film obtained from the same raw material as the SiC film formed on the substrate. Features.

  The method for producing CVD-SiC according to claim 3 is the method according to claim 1 or 2, wherein the support is a cylindrical shape having a diameter of 0.5 to 3 mm, a conical shape, a triangular pyramid shape, and a quadrangular pyramid. The shape is a polygonal pyramid shape such as a shape or a triangular plate shape.

  The method for producing CVD-SiC according to claim 4 is the method according to claim 1 or 2, wherein the support has a conical shape at a portion in contact with the substrate, and a diameter of a circular surface in contact with the substrate is 0.5 to 3 mm. The cone-shaped height is 1 to 50 mm, and the diameter of the cone-shaped bottom is 0.5 to 20 mm.

  In the present invention, when a SiC film is formed by a CVD method on a graphite substrate supported by a support formed from a SiC film obtained in advance by a CVD reaction, the SiC film is formed on the entire surface of the substrate, cracks, etc. The defects did not occur. Moreover, the said support tool was taken in into the formed SiC film, and was fully integrated (a yield was 100%).

  This was confirmed from the fact that when the notch was cut into the vicinity of the support and a fracture test was performed, a crack occurred inside the support. Furthermore, since this support does not affect the strength, electrical conductivity, etc., the entire surface of the coating can be used as a product, thereby improving the yield from a single film and reducing processing costs. Became possible.

  In the present invention, in a method of placing a base material on a base material holding jig via a support tool that contacts the base material and forming a SiC film on the base material surface by a CVD reaction, the support tool is formed by a CVD reaction. It is formed from the obtained SiC film, and preferably is formed from an SiC film obtained from the same raw material as the SiC film formed on the substrate.

  The SiC material used as the support is a single SiC film obtained by forming a SiC film having a thickness of about 3 mm on a graphite substrate and then removing the graphite substrate by oxidation or cutting. This material is processed into the desired shape using a diamond tool with a tool such as a hand leuter. The SiC support of the present invention supports the substrate, reduces the area of the support, and further integrates with the SiC coating. Because it is aimed, it does not require particularly precise machining.

  The support is preferably long enough to form a uniform CVD film thickness without interfering with the flow of the CVD raw material, and the contact (contact) area with the substrate is reduced as much as possible from the viewpoint of workability. It is desirable that the base material on which the thick SiC film is formed be sufficiently supported. It is desirable that the shape of the thin cylindrical shape is such that the tip of the thin circular cylinder is shaped into a conical shape and the conical portion is brought into contact with the substrate. In the case of a thin cylindrical shape, the diameter is 0.5 to 3 mm. It is preferable to do this. In addition, a conical shape, a polygonal pyramid shape such as a triangular pyramid shape, a quadrangular pyramid shape, or a triangular plate shape (a SiC single film is cut into a triangle shape and the apex portion with which the substrate abuts is formed on the contact surface) Even if it is a thing, a sufficient effect can be exhibited, and the thing of a triangular board shape becomes easy to manufacture compared with a cone shape. For example, a large-diameter thick SiC coating with a diameter of 400 mm and a thickness of 15 mm is formed by supporting three points using a triangular plate-shaped support tool having a base of 2 mm × 2 mm and a height of 15 mm at the part that contacts the substrate. It was confirmed that the CVD film was formed without dropping the substrate.

  When the portion of the support that comes into contact with the base material has a conical shape, the diameter of the circular surface that comes into contact with the base material is 0.5 to 3 mm, the height of the conical shape is 1 to 50 mm, and the diameter of the bottom of the conical shape is 0. By setting it as 5-20 mm, the balance with the supporting force with respect to a base material and the small area of a support part can be obtained. When the diameter of the circular surface in contact with the substrate is 3 mm or more, the SiC film is not formed on the support part, and the flow of the CVD raw material is hindered. Stress balance is lost and cracks tend to occur.

  When the portion of the support that comes into contact with the base material is a triangular pyramid shape, a quadrangular pyramid shape such as a quadrangular pyramid shape, or a triangular plate shape, the diameter of the surface that comes into contact with the base material (equivalent circle diameter: the same surface as the base material comes into contact The diameter of the circle when the circle has an area of 0.5 to 3 mm, the cone-shaped height or the triangular plate-shaped height is 1 to 50 mm, the diameter of the cone-shaped bottom or the diameter of the triangular plate-shaped bottom (equivalent circle diameter) : The diameter of the circle when the surface in contact with the substrate is a circle having the same area) is set to 0.5 to 20 mm, so that the balance between the supporting force with respect to the substrate and the reduction in the area of the supporting portion is achieved. Obtainable.

  The support according to the present invention can be used by providing a hole or incision perpendicularly to the end of the base material holding jig made of a graphite material or the like that holds the base material via the support, and inserting the hole or incision into the hole or incision. . Since there is a possibility that the end of the base material holding jig made of graphite material is cracked, it is the same shape as the SiC support tool, a hole with the same depth as the protrusion of the SiC support tool is provided, and it is heavy when the SiC support tool is installed. Even if it puts on, it is preferable without worrying about breaking.

  Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects of the present invention. In addition, these Examples show one embodiment of this invention, and this invention is not limited to these.

First, as a support material, a SiC simple substance film was prepared by the following method.
A disk-shaped graphite substrate having a diameter of 200 mm and a thickness of 7 mm is manufactured from high-purity graphite (G330 manufactured by Tokai Carbon Co., Ltd.). Thereafter, the disc-shaped graphite base material is put in a CVD apparatus, and the inside of the apparatus (furnace) is heated and held at a temperature of 1400 ° C., while using trichloromethylsilane as a raw material and hydrogen as a carrier gas, the graphite base material is formed by CVD. A SiC film is formed to a thickness of about 3 mm on the surface. Next, the graphite base material on which the SiC film is formed is taken out of the furnace, and the peripheral surface portion of the SiC film is removed by grinding to expose the peripheral surface of the graphite base material. And it put into the furnace of 900-1400 degreeC with the graphite base material pinched | interposed with the SiC film | membrane, supplied oxygen, and removed the graphite base material by oxidizing combustion, and obtained the SiC single-piece | unit film. The removal of the graphite base material is not limited to oxidation combustion, and may be performed by machining such as surface grinding after cutting and dividing.

Example 1
A cylindrical shape with a diameter of 2 mm is produced from the obtained SiC single film, a circular surface with a tip diameter of 0.5 mm, a cone-shaped height of 5 mm, and a cone-shaped bottom diameter of 2 mm is ground and processed. A support made of a product was produced. The columnar end of the support was caulked into a graphite substrate holding jig, and the height at which the conical shape was exposed from the graphite substrate holding jig was 10 mm.

  With the above support, three-point support was performed at a circumferential position of 390 mm in diameter on a graphite substrate having a diameter of 400 mm and a thickness of 8 mm, and a 4 mm-thick SiC film was formed on the substrate surface by CVD. As a result, a SiC film was formed on the entire surface of the substrate, there was no difference in film thickness between the central portion and the peripheral portion where the SiC support was taken in, and no defects such as cracks were observed. The support was incorporated into the formed SiC film and fully integrated (yield was 100%). In the CVD method, the temperature in the furnace was kept at 1400 ° C., and an SiC film was formed on the surface of the graphite substrate using trichloromethylsilane as a raw material and hydrogen as a carrier gas.

Example 2
A cylindrical shape with a diameter of 3 mm was produced from the SiC single film produced above, and a SiC support having a circular surface with a tip diameter of 3 mm was produced. Using this support and holder, a graphite substrate having an outer diameter of 400 mm, an inner diameter of 200 mm, and a thickness of 6 mm is supported at a circumferential position with a diameter of 210 mm, and the substrate surface is the same as in Example 1. Under the conditions, a SiC film having a thickness of 4 mm was formed by a CVD method. As a result, a SiC film was formed on the entire surface of the substrate, and there was no difference between the central portion and the peripheral portion where the SiC support was taken in, and no defects such as cracks were observed. The support was incorporated into the formed SiC film and fully integrated (yield was 100%).

Example 3
From the SiC single film (thickness: 2 mm) produced as described above, a triangular plate-shaped SiC support tool having a circle-equivalent diameter of 1.6 mm (width 1 mm × thickness 2 mm) at the front end in contact with the substrate A support having a height of 20 mm and an equivalent circle diameter of 7.1 mm (width 20 mm × thickness 2 mm) at the bottom is molded, and the support is caulked to the end of a graphite base material holding jig. The height exposed from the material holding jig was 10 mm.

  With the above support, three-point support is performed at a circumferential position with a diameter of 390 mm on the same graphite substrate as in Example 1, and 4 mm thick SiC is formed on the substrate surface by the CVD method under the same conditions as in Example 1. A film was formed. As a result, a SiC film was formed on the entire surface of the substrate, there was no difference in film thickness between the central portion and the peripheral portion where the SiC support was taken in, and no defects such as cracks were observed. The support was incorporated into the formed SiC film and fully integrated (yield was 100%).

Comparative Example 1
In the process of forming a 4 mm thick SiC film on a graphite substrate having a diameter of 400 mm and a thickness of 8 mm by a CVD method, a round bar-shaped support was formed from sintered SiC. The equivalent circle diameter of the contact surface with the substrate was 5 mm, and the height of the round bar was 10 mm.

  When the above support is caulked to the end of the graphite base material holding jig, three points are supported at a position of the outer periphery of the graphite base material of 390 mm, and a 4 mm thick SiC film is formed on the base material surface by the CVD method. The SiC film was not formed on the periphery where the SiC support was present, and the yield was only 20%. Moreover, since the film thickness of the SiC film formed around the round bar-shaped support was small, it was not incorporated into the SiC film on which the support was formed and integrated.

Comparative Example 2
In the step of forming a 4 mm thick SiC film on a graphite substrate having a diameter of 400 mm and a thickness of 8 mm by a CVD method, a cylindrical pin shape tip having a diameter of 2 mm is formed into a conical shape from a SiC-coated graphite material, and then 100 μm A support was prepared in which a thick SiC coating was applied and the conical portion was brought into contact with the substrate. A support having a diameter of 1 mm at the front end in contact with the base material, a conical height of 5 mm, and a conical bottom of 2 mm in diameter is caulked into the end of the graphite base material holding jig, and made of graphite. The height at which the conical portion was exposed from the substrate holding jig was 10 mm.

  With the above support tool, three-point support was performed at a position of the outer periphery of the graphite base material of 390 mm, and a SiC film having a thickness of 4 mm was formed on the base material surface by the CVD method. The film could not withstand the weight and was damaged.

Comparative Example 3
In the process of forming a 4 mm thick SiC film on a graphite substrate having a diameter of 400 mm and a thickness of 8 mm by CVD, cone-shaped SiC-coated graphite was formed as a support. The equivalent circle diameter of the contact surface with the substrate was 5 mm, the height of the conical shape was 5 mm, and the diameter of the bottom of the conical shape was 10 mm.

  When the above support is caulked to the end of the graphite base material holding jig, three points are supported at a position of the outer periphery of the graphite base material of 390 mm, and a 4 mm thick SiC film is formed on the base material surface by the CVD method. The SiC film was not formed on the periphery where the SiC-coated graphite support was present, and the yield was only 20%. Moreover, since the film thickness of the SiC film formed around the round bar-shaped support was small, it was not incorporated into the SiC film on which the support was formed and integrated.

Comparative Example 4
In the step of forming a 4 mm thick SiC film by a CVD method on a graphite substrate having a diameter of 400 mm and a thickness of 8 mm, a three-dimensional network structure in which porous glassy carbon was coated with a SiC film was produced as a support. The equivalent circle diameter of the contact surface with the substrate was 10 mm, and the height of the mesh structure was 10 mm.

  When the above support is caulked to the end of the graphite base material holding jig, three points are supported at a position of the outer periphery of the graphite base material of 390 mm, and a 4 mm thick SiC film is formed on the base material surface by the CVD method. In addition, the formation of the SiC film in the peripheral portion where the support was present was small, and the yield was only 10%. Moreover, since the film thickness of the SiC film formed around the support was small, it was not incorporated into the SiC film on which the support was formed and integrated.

Claims (4)

In the method of placing a base material on a base material holding jig through a support tool that comes into contact with the base material and forming a SiC film on the base material surface by a CVD reaction, the support tool is a SiC obtained by the CVD reaction. A method for producing CVD-SiC, wherein the method is formed from a film. The method for producing CVD-SiC according to claim 1, wherein the SiC film formed on the support is an SiC film obtained from the same raw material as the SiC film formed on the substrate. The portion of the support that contacts the base material has a cylindrical shape having a diameter of 0.5 to 3 mm, a conical shape, a triangular pyramid shape, a quadrangular pyramid shape such as a quadrangular pyramid shape, or a triangular plate shape. Or the manufacturing method of CVD-SiC of 2. The support tool has a conical shape at the portion that contacts the base material, the diameter of the circular surface that contacts the base material is 0.5 to 3 mm, the height of the conical shape is 1 to 50 mm, and the diameter of the conical bottom portion is 0.5. The method for producing CVD-SiC according to claim 1 or 2, wherein the thickness is 20 mm.