JPH0649946B2 - Method for manufacturing tubular member - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a tubular member, and more particularly to a method for manufacturing a long tubular member suitable for use as a reaction tube for semiconductor production.

[Prior Art] Conventionally, as a reaction tube for semiconductor production, a quartz tube or a tube provided with a mullite or silicon carbide soaking liner tube on the outside thereof has been used. However, a quartz tube has drawbacks such as fragility and devitrification due to contamination and the like, and lacks strength particularly at high temperatures, and particularly long ones are easily bent.

Therefore, it is expected to provide a reaction tube for semiconductor production made of a material other than quartz.

By the way, in recent years, since non-oxide ceramics such as silicon carbide and silicon nitride have excellent heat resistance characteristics, application to various industrial materials has been studied, and non-oxide ceramics have been used. It is conceivable to manufacture a reaction tube for semiconductor manufacturing. In this case, since non-oxide ceramics are difficult to sinter, it is necessary to use an appropriate sintering aid or a reaction sintering method to form a sintered body.

Further, there is a method of obtaining a pipe by using a tubular body as a vapor deposition base material, supplying a reaction gas to the inner surface or the outer surface while heating the vapor deposition base material to form a CVD coating, and then removing the base material by an appropriate method. Are known. (For example, JP-A-58-
177461).

[Problems to be Solved by the Invention] Of the above-mentioned conventional methods, a method using a sintering aid or a reaction sintering method requires a great deal of labor for high purification, and is not only expensive, As the powder process is adopted, there is a limit to high purification.

On the other hand, according to the CVD method as disclosed in JP-A-58-177461, although dense and high-strength ceramics can be obtained,
Since the material of the base material is a metal material such as copper or aluminum, the operation of removing the base material is a wet dissolution process, which complicates the manufacturing process.

Therefore, it is considered that the material of the base material is replaced with graphite from a metal material. However, in order to form graphite into a tubular base material, it is necessary to perform a very troublesome boring process,
High base material cost. Further, it is not easy to perform boring of a long product with high accuracy, and it is difficult to manufacture a long tubular member.

[Means and Actions for Solving Problems] In the present invention, a graphite ring or a graphite cylinder having an equal diameter is coaxially connected and arranged, and a ceramic coating is formed on the peripheral surface of this connector by a CVD process to form a tubular shape. A method of forming a body, wherein the outer peripheral corners of the graphite ring or the graphite cylinder are chamfered and then connected and arranged, and during the CVD treatment, the outer peripheral corners are selectively heated to selectively select the outer peripheral corners. The method for producing a tubular member is characterized in that it has a step of depositing a CVD deposit on the substrate.

According to the present invention, a tubular member made of high-purity and dense ceramics or covered with a ceramic coating can be extremely easily manufactured.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

In the present invention, the graphite rings or graphite cylinders 1 having the same diameter are coaxially connected and arranged (for example, stacked) to form the connection body 2, and then the ceramic coating is formed on the peripheral surface of the connection body by the CVD process.

In forming this ceramic coating, as shown in FIGS. 1 and 2, the outer peripheral corners of the ring or cylinder 1 are chamfered, and a recess 3 is formed around the joint of the rings or cylinders 1. 3 is selectively heated to the CVD processing temperature to selectively deposit a CVD deposit 4 in the recess 3 as shown in FIG.

By carrying out such a treatment, the rings or the cylinders 1 are bonded to each other through the precipitate 4, and the strength of the bonded body 2 and thus the strength of the obtained tubular member can be increased. In order to selectively heat the concave portion 3, it is preferable to irradiate the concave portion 3 with a laser beam having an appropriate intensity.

The ring or cylinder 1 is most preferably the same in inner diameter and outer diameter, but when the CVD coating is formed on only one of the inner peripheral surface and the outer peripheral surface of the connection body, only the inner diameter or outer diameter is the same. It may be one.

Although the ring or the cylinder is formed in a perfect circle in FIG. 1, in the present invention, it is an elliptic cylinder or a square cylinder (for example, a hexagonal cylinder).
It may be formed into a shape such as.

This CVD coating may be formed on both the inner peripheral surface and the outer peripheral surface. However, when the graphite is burned and removed in a later step, the CVD coating is formed only on one of the inner peripheral surface and the outer peripheral surface. Preferably. The CVD coating may be formed according to a conventional method, for example, by placing it in a CVD processing apparatus and heating it to an appropriate CVD reaction temperature,
A CVD source gas may be introduced.

This CVD coating is a ceramic in the present invention. Specific materials include non-oxide ceramics such as silicon carbide and silicon nitride, and oxide-based ones such as magnesia and alumina. However, in order to manufacture a tubular member used as a reaction tube, silicon carbide is deposited. Is preferred. Various source gases are known for use in the CVD deposition reaction of silicon carbide, and any of them can be adopted in the present invention. For example, as is well known, C
SiC can be deposited by thermally decomposing H ₃ SiCl ₃ . SiC can also be deposited by reducing SiCl ₄ with a hydrocarbon such as CH ₄ .

The thickness of the CVD coating film to be deposited is not particularly limited, and the CVD processing conditions are selected so that the resulting tubular member has a thickness that satisfies the corrosion resistance and strength required.

In the present invention, for example, by adjusting the length of the CVD process, it is possible to manufacture a tubular member having an arbitrary wall thickness from a very thin wall to a large wall.

After depositing such a CVD coating, the combustion of the graphite ring or the graphite cylinder 1 is removed if necessary. In order to carry out this combustion removal, it is sufficient to maintain the temperature range in which the graphite burns in the oxidizing atmosphere. At this time, the atmosphere can be switched to oxygen or air while being held in the CVD processing apparatus, so that combustion removal of the graphite ring or the cylinder can be continuously performed in the processing apparatus. If you do this,
It is possible to prevent the occurrence of thermal stress due to the difference in thermal expansion between the base material and the CVD coating. Of course, in the present invention, the graphite may be burned and removed after once returning to room temperature. Also,
Obviously, the graphite may be burned at a temperature different from the CVD treatment temperature.

[Example] Example 1 An outer peripheral corner portion of a graphite cylinder having an inner diameter of 90 mm, an outer diameter of 100 mm and a length of 5 cm was squared at an angle of 45 ° for about 8 mm, and this was cut to 10 mm.
The individual pieces were stacked as shown in FIG. 1 to form a connected body.

This connection body was subjected to a CVD process by a laser CVD processing device to form a SiC film. During the CVD process, the connector was rotated around its axis at 5 rpm, and the recess formed by chamfering was irradiated with a laser beam to be heated, and only the recess was sequentially filled with the CVD deposit. Laser CV
A transparent small window was provided on the side wall of the D processing apparatus, and a laser beam was irradiated from this small window toward the concave portion of the connection body inside the apparatus. A carbon dioxide gas laser having an output of 5 kW was used as the laser.

Then, the connected body is loaded into a CVD processing apparatus, and 1500
SiC as a CVD source gas while being uniformly heated to ℃
l ₄ was circulated at a rate of 0.6 / min and C ₃ H ₈ was circulated at a rate of 0.1 / min to form a CVD coating having a thickness of 0.3 mm on both the inner and outer peripheral surfaces of the connector.

After slowly cooling until the temperature inside the apparatus reached 200 ° C., it was taken out from the apparatus. As a result, a tubular member having a length of 50 cm, the entire peripheral surface of which was covered with the SiC-CVD coating, and which had a high joint strength between the tubular members was obtained.

[Effects of the Invention] As is clear from the above description, according to the present invention, a long tubular member made of ceramics or coated with ceramics can be obtained at low cost. The ceramic constituting the tubular member obtained by the present invention is dense and highly pure because it is formed by the CVD method.

In the case of depositing silicon carbide according to the present invention, the tubular member to be obtained is suitable as a reaction tube for semiconductor production, because it is made of only silicon carbide or silicon carbide and graphite and can be uniformly heated. Of course, the tubular member produced by the method of the present invention can be used for various other purposes.

[Brief description of drawings]

Each of FIGS. 1 and 2 is a cross-sectional view showing a method for manufacturing a tubular member according to the present invention. 1 ... Ring or cylinder, 2 ... Connection body.

Claims (2)

[Claims] 1. A method of manufacturing a tubular member, wherein graphite rings or graphite cylinders of equal diameter are coaxially connected and arranged, and a ceramic coating is formed on the peripheral surface of the connected body by a CVD process to form a tubular body. Then, the outer peripheral corners of the graphite ring or the graphite cylinder are chamfered and then connected and arranged, and during the CVD treatment, the outer peripheral corners are selectively heated to be selectively covered with the CVD deposits. A method for manufacturing a tubular member, comprising a step of attaching the tubular member. 2. The manufacturing method according to claim 1, wherein the graphite is burned and removed after the CVD treatment.