JP4455895B2 - Method for producing vapor-deposited ceramic coating material - Google Patents

Description

  The present invention relates to a carbon material such as a graphite material, a carbon fiber reinforced carbon composite material, or a vapor-phase-deposited ceramic coating material in which a ceramic film is coated on the surface of a base material such as ceramics or metal by a chemical vapor deposition method (CVD method). And its manufacturing method. In the following description, the case where the base material is made of graphite and the ceramic is made of SiC will be mainly described.

  For example, a SiC-coated graphite material in which a SiC film is formed as a ceramic film on the surface of a graphite substrate by a chemical vapor deposition method (hereinafter also referred to as a CVD method) is coated with a high-purity SiC film on the surface. Due to its excellent non-contaminating property, high thermal shock resistance against rapid heating and quenching, chemical stability and high corrosion resistance, it can be used as a heat treatment component in semiconductor manufacturing for susceptors, liner tubes, process tubes, wafer boats, It is useful as a member requiring high purity and heat resistance, such as a crystal pulling device member.

A method for producing a SiC coating material by depositing SiC on the surface of a substrate by CVD is, for example, CH ₃ SiCl ₃ , (CH ₃ ) containing Si atoms and C atoms in one molecule using hydrogen gas as a carrier gas. ₃ SiCl, methods for reducing thermal decomposition in the gas phase an organic silicon compound such as CH ₃ SiHCl _2, or, causes the carbon compounds such as silicon compounds and CH _4, such as SiCl ₄ by vapor phase reaction SiC is a vapor phase deposition Done in the way.

  However, in the film formation by the CVD method, the base material is placed on the base material holder in the CVD reaction vessel through a support jig such as a graphite pin or bar covered with a graphite or SiC film, and the above-mentioned Since the raw material gas is supplied and vapor deposition is performed by the CVD reaction, the raw material gas cannot enter the surface of the base material in contact with the support jig, so that there is a disadvantage that the SiC film is not formed. Therefore, in order to coat the entire surface of the substrate with the SiC film, the film is formed again by changing the position of the support jig. That is, at least two coating processes are required.

  In order to eliminate this drawback, Patent Document 1 discloses a method of forming a SiC film in which a step of forming a SiC film on the surface of the graphite plate and a step of changing the support position of the graphite plate in the furnace are alternately performed, A quartz cover having a graphite plate support rod on its upper surface is installed, and a rotary cylinder provided with a flange for supporting a part of the quartz plate is placed up and down in a furnace concentric with the quartz cover in a furnace having an open gas introduction tube. A SiC film forming apparatus characterized in that it is rotatably installed has been proposed. However, this method and apparatus can be applied only to a graphite plate having a limited shape, and the facilities are complicated, so that there is a problem that the capital investment cost increases. Furthermore, when changing the support position of the graphite plate, the CVD reaction must be interrupted once. When the interrupted CVD reaction is resumed, the crystal properties of the precipitated SiC grains change, so that the part is easily peeled off. There are also difficulties.

  Further, in Patent Document 2, a set of gantry comprising an upper gantry and a lower gantry is arranged, the upper gantry is fixed, the lower gantry is movable up and down, and a support bar is installed on each gantry. A silicon carbide coating apparatus has been proposed in which these support bars support a graphite substrate. This is because the supporting position is changed by the vertical movement of the lower pedestal during the coating process, but in this case as well, there is a limitation in the shape of the graphite base material, and there is a drawback that it is difficult to apply to small items. Furthermore, if the weight balance is bad or the level is not maintained, there is a possibility that it will fall off the support bar.

Further, Patent Document 3 discloses a CVD apparatus in which a support member for supporting a substrate to be processed is disposed in a CVD reactor, and the support member includes an impact mechanism that applies intermittent microshock. And a CVD film forming method characterized in that coating is performed by sequentially displacing the contact portion between the substrate to be processed and the support member by applying a microshock. However, it is difficult to change the support position accurately by applying intermittent microshock, when the shape of the substrate to be processed is complicated or large heavy objects, and when the substrate to be processed is vertically long Even has the risk of falling.
JP 58-125608 A Japanese Patent Laid-Open No. 1-205076 JP-A-8-1000026

  As described above, a technique for reliably and safely applying a ceramic coating to the entire surface of the substrate by chemical vapor deposition has not yet been established, and the development of a technique for coating the entire surface of the substrate with a single CVD process has been established. Is desired.

  Therefore, the present inventor deposited and coated ceramics on the surface of the base material by a CVD reaction to produce a ceramic coating material, without moving the base material on the support jig at the time of the CVD processing. In order to reliably and safely coat ceramics on the entire surface of the substrate, we have intensively studied, and without incorporating a complicated physical mechanism in the CVD apparatus, the ceramic can be applied to the entire surface of the substrate by a single CVD process. Technology for deposition and coating was developed.

  In other words, the object of the present invention is as a ceramic coating material in which a ceramic such as SiC is deposited on the surface of a substrate such as graphite by a CVD reaction, and the ceramic is coated on the entire surface of the substrate reliably and safely by a single coating process. An object of the present invention is to provide a vapor-phase deposited ceramic coating material and a method for producing the same.

In the method for producing a vapor-deposited ceramic coating material according to the present invention, a base material is placed on a support jig in a CVD reaction vessel, and after depositing ceramic on the base material surface by a CVD reaction, the support jig is This is a manufacturing process in which the ceramic coating material is removed by pulling and breaking, and the diameter of the support jig trace is not more than 7.5 times the ceramic coating film thickness near the support jig, or of the support jig before coating the ceramic. Set the diameter to 5.5 times the ceramic coating thickness near the support jig and use a support jig made of the same or equivalent material as the ceramic to be coated , or use the same ceramic as the ceramic to be coated. It is a structural feature that a covered support jig is used.

  According to the present invention, as a ceramic coating material in which ceramics such as SiC are deposited on the surface of a substrate such as graphite by a CVD reaction, the ceramic is coated on the entire surface of the substrate reliably and safely in a single coating process. In addition, a vapor-deposited ceramic coating material and a method for manufacturing the same can be provided.

  Since the surface of the supporting jig on which the substrate is placed in the CVD reactor is in contact with the substrate is much larger than the thickness of the ceramic coating to be coated, usually after depositing and coating the ceramic on the substrate surface, The support jig does not break when removing the substrate. Therefore, the ceramic coating is not formed on the base material surface in contact with the support jig, and remains uncoated.

  However, when the size of the support jig surface in contact with the substrate is reduced, for example, when the diameter of the cylindrical support jig is reduced, the support jig breaks at the coated surface when the support jig is removed after the ceramic is coated. It will be destroyed. In other words, the tip of the support jig remains on the substrate side. In this case, if the material of the support jig is the same as, or equivalent to, the ceramic coated, the support jig is supported. The tip of the jig is integrated with the ceramic coating. That is, the relationship between the diameter of the support jig and the film thickness of the ceramic coating in the vicinity thereof is important.

  As a result of intensive studies focusing on this phenomenon, the present inventor reduced the diameter of the cylindrical support jig, placed the base material, formed a ceramic film by CVD reaction, and then attached the support jig. When the substrate is removed due to destruction, a dimple-like depression is formed on the coating surface of the substrate, and the diameter of the dimple is the diameter of the supporting jig on which the ceramic coating is formed after the CVD reaction, that is, the supporting jig. We found that it was equal to the diameter of the trace.

  In this case, it was experimentally confirmed that there is a relationship shown in FIG. 1 between the dimple diameter and the dimple depth. From the regression line in FIG. 1, it was experimentally determined that the dimple diameter corresponds to 7.5 times the dimple depth.

  Therefore, in order to coat the base material surface in contact with the support jig with the ceramic film, it is only necessary to make the ceramic film thickness thicker than the dimple depth as shown in FIG. In FIG. 2, 1 is a base material, 2 is a ceramic coating, 3 is a support jig after coating the ceramic coating, 4 is a dimple, and 5 is a support jig left on the base material side when the support jig is removed. , X is the diameter of the support jig after coating the ceramic film (equal to the diameter of the trace of the support jig, that is, the dimple diameter), Y is the depth of the dimple, and Z is the thickness of the ceramic coating near the support jig. It is.

  From FIG. 1 and FIG. 2, if the diameter of the dimple, that is, the diameter X of the cylindrical support jig trace is not more than 7.5 times the ceramic coating film thickness Z in the vicinity of the support jig, When the substrate is removed, the tip of the support jig remains on the surface of the base material without fail, and the surface of the base material 1 is not exposed. It is possible to cover the entire surface.

  In this case, when the support jig is removed by pulling and the ceramic covering material is removed, the trace of the support jig becomes a dimple shape. When the support jig is broken by bending or compression, the dimple may become shallow, or a part of the jig may remain on the coated surface as a protrusion without becoming a dimple. These fracture modes are preferable because the substrate is difficult to be exposed, but it is always difficult to break with a bending stress or a compressive stress. Therefore, even when the support jig is removed by tensile fracture where the dimple is deepest, if the diameter of the trace of the support jig is not more than 7.5 times the ceramic coating thickness near the support jig, the tip of the support jig The part remains on the substrate surface, and the substrate surface is not exposed.

  On the other hand, as shown in FIG. 3, the diameter of the support jig after ceramic coating is larger than the diameter before ceramic coating by twice the film thickness of the ceramic coating. That is, in FIG. 3, 6 is a support jig before ceramic coating, and when the diameter is X0, the diameter X of the support jig 3 after ceramic coating is X = X0 + 2Z. 3 are the same as those in FIG. 2, 1 is a base material, 2 is a ceramic coating, 3 is a supporting jig after coating the ceramic coating, 4 is a dimple, and X is a supporting jig after coating the ceramic coating. The diameter (equal to the diameter of the support jig trace, that is, the dimple diameter), Y is the depth of the dimple, and Z is the ceramic coating thickness near the support jig.

  1, 2 and 3, when the diameter X0 of the support jig 6 is 5.5 times or less the film thickness Z of the ceramic coating near the support jig, the support jig is removed after the ceramic coating. The diameter X of the jig trace (dimple) is 7.5 times or less of Z, and a film can be formed on the substrate surface in contact with the support jig.

  In the above explanation, the case of a cylindrical shape was explained as an example of the shape of the supporting jig. However, in the case of a polygonal column, if the diameter of the circumscribed circle of the polygon is regarded as the diameter of the cylinder, it can also be applied to the polygon. Furthermore, a cone or a polygonal cone is applicable.

  As described above, according to the present invention, the support jig formed by removing the support jig by pulling fracture after performing the CVD reaction by reducing the diameter of the support jig for placing the base material in the CVD reaction vessel. The diameter of the jig trace is 7.5 times or less of the ceramic coating thickness near the support jig, or the diameter of the support jig before ceramic coating is 5.5 times the ceramic coating thickness near the support jig. Set and controlled as follows, and the support jig material is the same as, equivalent to, or covered with the same ceramic, so that the support jig tip remains on the substrate surface. A vapor-phase-deposited ceramic coating material that can be integrated with a material surface, and which is coated with ceramics on the entire surface of the substrate reliably and safely by a single coating process, and a method for producing the same are provided.

  Examples of the present invention will be specifically described below in comparison with comparative examples.

Example 1
As shown in FIG. 4, a disc-shaped graphite substrate 7 having a diameter of 250 mm and a thickness of 5 mm is placed on three columnar support jigs 8 having a diameter of 300 μm and a length of 5 mm, and placed in a CVD reaction vessel. I set it. The columnar support jig was produced by grinding and polishing a CVD-SiC molded body obtained by depositing SiC on a graphite substrate by CVD and then burning and removing the graphite substrate.

After exhausting the air in the CVD reaction system, the system was heated to a temperature of 1100 ° C., and hydrogen gas was introduced to replace the system with a hydrogen gas atmosphere. Next, using methyltrichlorosilane (CH ₃ SiCl ₃ ) as the source gas and hydrogen gas as the carrier gas, the concentration of methyltrichlorosilane in the mixed gas of methyltrichlorosilane / hydrogen is set to 10 Vol% and the CVD reaction is performed. Then, a SiC film having a thickness of 120 μm was formed on the surface of the graphite substrate.

  Thereafter, when the cylindrical support jig was removed by pulling and breaking, it was confirmed that the support jig was bent at the coating surface, and the tip of the support jig remained on the substrate side, and was integrated with the SiC coating. The film thickness of the SiC coating near the support jig was 100 μm because the gas around the source gas was slightly worse. Moreover, it was 500 micrometers when the diameter of the trace of a support jig was measured with the microscope. That is, the diameter X0 of the support jig was 300 μm, the diameter X of the support jig trace (dimple) was 500 μm, and the film thickness Z of the SiC coating near the support jig was 100 μm. Although the substrate surface of the support jig trace was examined closely, the exposed portion of the substrate was not confirmed, and it was confirmed that the entire surface of the substrate was covered with the SiC film.

Example 2
In Example 1, the diameter X0 of the cylindrical support jig was changed to 250 μm, and after the SiC film having a film thickness of 60 μm was coated, the support jig was pulled and broken to remove the support jig trace (dimple). The diameter X was 350 μm, the thickness Z of the SiC coating near the support jig was 50 μm, and no exposed portion was observed on the base material surface of the support jig trace.

Example 3
In order to increase the weight of the base material, a disk-shaped graphite base material having a diameter of 500 mm and a thickness of 50 mm was used. In support, a 60 μm thick SiC coating was coated. When the support jig is pulled and removed, the support jig is dense, so the gas around the support jig is particularly bad, and the SiC film thickness Z near the support jig is 30 μm. The diameter X of the trace (dimple) was 180 μm. However, no exposed portion was confirmed on the base material surface of the support jig trace.

Comparative Example 1
In Example 1, when the film thickness of the SiC film to be formed was 60 μm, the film thickness Z in the vicinity of the support jig was 50 μm, and the diameter X of the support jig trace (dimple) was 400 μm. Moreover, the exposed part by which the SiC film was not coat | covered was recognized by the base-material surface of a support jig trace.

Example 4 and Comparative Example 2
A columnar support jig was prepared using a material obtained by coating SiC on a graphite material by a CVD method, and an SiC film was formed and coated using the support jig.

Example 5
A SiC film was formed and coated using a columnar support jig made of sintered SiC.

Example 6 and Comparative Example 3
A SiC film was formed and coated using a conical support jig produced from a CVD-SiC molded body.

Example 7
A SiC film was formed and coated using a triangular prism-shaped support jig made from a CVD-SiC molded body.

Example 8
A SiC film was formed and coated using a triangular pyramid-shaped support jig made from a CVD-SiC molded body.

  Table 1 summarizes the coating conditions and the coating state of the substrate surface of the graphite material in which the SiC substrate was coated with the SiC film by the CVD method in this way.

  From the results shown in Table 1, among the SiC-coated graphite materials manufactured by coating the SiC coating on the graphite substrate surface by the CVD method and then removing the supporting jig by tensile fracture, the diameter X of the supporting jig trace and the supporting jig The SiC-coated graphite material of the example in which the ratio (X / Z) with the SiC film thickness Z in the vicinity of the tool was controlled to 7.5 or less, or the diameter X0 of the supporting jig before the SiC coating and the SiC in the vicinity of the supporting jig The SiC-coated graphite material of the example in which the ratio (X0 / Z) with the film thickness Z was controlled to 5.5 or less was coated with SiC on the entire surface, and no exposed portion was observed on the substrate surface. In contrast, the SiC-coated graphite material of the comparative example in which X / Z exceeds 7.5 or X0 / Z exceeds 5.5 is confirmed to have an exposed portion where the substrate surface is not coated with SiC. It was.

  In this example, the case where the graphite base material is coated with SiC is exemplified, but the material of the base material is not limited and can be applied to other ceramics capable of vapor phase deposition such as alumina and zirconia other than SiC. It is.

FIG. 5 is a diagram showing the relationship between the diameter and depth of a support jig trace (dimple) generated when the support jig is pulled and broken after the CVD reaction. It is the schematic diagram which showed the state when the support jig | tool was pulled and destroyed and removed after coat | covering the ceramic film on the base-material surface by CVD reaction. It is the schematic diagram which showed the state when the support jig | tool was pulled and fractured and removed after coat | covering the ceramic film on the base-material surface by CVD reaction with the diameter of the support jig before coating | coated with a ceramic film. It is a perspective view which shows the state which mounted the disk-shaped graphite base material applied in the Example on three cylindrical support jigs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Ceramic film 3 Support jig after ceramic film coating 4 Dimple 5 Tip part of the support jig remaining on the base material side when the support jig is removed by pulling and breaking 6 Support treatment before ceramic film coating Tool 7 Disc-shaped graphite base material used in the example 8 Cylindrical support jig used in the example X Diameter of the support jig after the ceramic coating (equal to the diameter of the trace of the support jig, that is, the diameter of the dimple)
Y Dimple depth Z Ceramic coating film thickness near support jig X0 Diameter of support jig before ceramic coating

Claims (1)

It is a manufacturing process in which a base material is placed on a support jig in a CVD reaction vessel, ceramics are deposited and coated on the surface of the base material by a CVD reaction, and then the support jig is pulled and broken to remove the ceramic coating material. 4. The diameter of the trace of the support jig is not more than 7.5 times the ceramic coating thickness near the support jig, or the diameter of the support jig before coating the ceramic is equal to the ceramic coating thickness near the support jig. A gas phase characterized by using a support jig made of the same or equivalent material as the ceramic to be coated , or using a support jig coated with the same ceramic as the ceramic to be coated. A method for producing a deposited ceramic coating material.

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