JPH0611486B2 - Method for manufacturing ceramic tubular member - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a ceramic tubular member,
In particular, the present invention relates to a method for manufacturing a ceramic 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 easy cracking and devitrification due to contamination. In particular, the strength at high temperature is insufficient, and as a result of bending, it is becoming difficult to cope with recent large-diameter Si wafers.

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, a pipe or a rod is used as a vapor deposition base material, a reaction gas is supplied to the inner surface or the outer surface while heating the vapor deposition base material to form a CVD film, and then the base material is removed by an appropriate method to obtain a pipe. The method is 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, although extremely dense and high-purity ceramics can be obtained, when manufacturing a tubular member having a large wall thickness and high rigidity, the CVD process requires a long time, resulting in poor production efficiency. is there.

Although it is possible to obtain a ceramic reaction tube by depositing high-purity silicon carbide by a CVD method on the inner surface of the sintered silicon carbide tube, diffusion of impurities from the base material silicon carbide and formation of a film Since the base material silicon carbide may be exposed due to peeling or cracking, it is expected to provide a reaction tube composed only of a CVD film.

[Means for Solving the Problems] The present invention is intended to manufacture a tubular member made of a CVD CVD film of ceramics by the following steps to be sequentially performed.

A ceramic coating is formed on both the inner and outer peripheral surfaces of the cylindrical base material having a large number of through holes in the peripheral wall and the inner surface of the through hole by a CVD process, and then the cylindrical base is formed. The material is removed by burning or melting to form a double cylindrical tubular member made of a CVD film having a large number of through holes in its peripheral wall. Further, the through holes are filled with a heat-resistant material, and the double cylindrical tubular member A ceramic coating is formed on the inner peripheral surface and the outer peripheral surface by a CVD process.

According to the present invention, it is possible to extremely easily manufacture a tubular member made of ceramics having a high rigidity even if the wall thickness is small.

The steps of the present invention will be described below in more detail with reference to the drawings.

Process In the present invention, as the base material, a cylindrical base material 2 which is made of a material that can be removed by combustion or dissolved and has a large number of through holes 1 in its peripheral wall as shown in FIG. 1 is used.

As the base material, a material that can withstand the CVD processing temperature is used. Its thickness is thinner than the intended thickness of the tubular member by the thickness of the CVD coating.

As the base material that can be removed by combustion, in addition to carbon (regardless of its crystal form), synthetic resin or paper can be used. Examples of the base material that can be dissolved and removed include metals such as aluminum and nickel, and synthetic resins that dissolve in an organic solvent.

Although a cylindrical base material is used in FIG. 1, a base material having an elliptic cylinder shape, a rectangular cylinder shape (for example, a hexagonal cylinder shape) or the like may be used in the present invention.

The through holes 1 formed in the base material 2 are preferably evenly distributed as shown in the figure. Further, the diameter and the number of the through holes 1 to be installed are arbitrary, but in the case of manufacturing a reaction tube for semiconductor production having a diameter of about 100 to 300 mm, the diameter is 2 to 10 m.
It is preferable to provide about 0.2 to 1 through hole of about m per cm ² . The through hole 1 may be a circular hole or a square hole.

In the present invention, such a cylindrical substrate is subjected to a CVD treatment, and CV is formed on the inner and outer peripheral surfaces and the inner surface of the through hole.
Form D coating. The CVD coating may be formed according to a conventional method, for example, by placing it in a CVD processing apparatus,
The CVD source gas may be introduced by heating to a suitable CVD reaction temperature.

This CVD coating is a ceramic in the present invention. Specific materials may be non-oxide ceramics such as silicon carbide and silicon nitride, as well as 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 thickness will satisfy the strength required for the tubular member to be obtained.

In the present invention, as a matter of course, the thickness of the CVD film can be adjusted by adjusting the length of the CVD treatment, for example.

Step After depositing such a CVD film, the substrate is removed. In order to remove this base material, combustion removal or dissolution removal is performed as described above. In order to remove by burning, it is sufficient to keep the temperature in the temperature range where the base material 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 the substrate can be continuously burned and removed in the processing apparatus. This makes it 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 substrate may be burned and removed after returning to room temperature. It is also clear that the substrate may be burned at a temperature different from the CVD processing temperature.

When the base material is dissolved and removed, for example, when the base material is a metal such as aluminum or nickel, an acid having an appropriate concentration is used. Further, aluminum can be dissolved and removed even with an alkali. Further, when the base material is a synthetic resin,
You may use the organic solvent which can melt | dissolve it at a suitable speed.

By removing such a base material, as shown in FIG. 2, a double-cylindrical member including an inner cylinder 3, an outer cylinder 4, a column portion 5 connecting these, and a through hole 6 penetrating the column portion 5. 7 is obtained. Prior to removing the base material in this step, at least one end, preferably both ends, of the CVD-coated base material 2 is cut off to expose the base material to be removed to the outside as shown in FIG. It is preferable to form the start of burn-off or dissolution removal. The end face or end of the base material may be polished to expose the base material to be removed. Alternatively, if measures are taken so as not to form the CVD coating on the end portion or the end surface of the base material, the step of cutting or polishing the end portion or the end surface is unnecessary.

Step The through hole 6 of the double cylindrical member 7 is filled with a heat resistant material 8 as shown in FIG. As this heat-resistant material 8,
A carbonaceous material such as graphite is preferable, but a ceramic powder may be used. In the case of ceramic powder, the same material as the ceramic deposited by CVD is suitable.

Step Next, as shown in FIG. 5, CVD coatings 9 and 10 are formed on the inner peripheral surface and the outer peripheral surface of the double cylindrical member 7. As a result, the heat-resistant material 8 is coated and the tubular member 11 having a double cylindrical shape can be formed. The same material as the CVD coatings 3 and 4 is preferable, but different materials may be used as long as the difference in coefficient of thermal expansion is small. The thickness of the CVD coatings 9 and 10 is not particularly limited. Since the double tubular tubular member 11 thus obtained has its rigidity mainly due to the double tubular structure, the CVD coatings 3, 4, 9,
With respect to 10, it is possible to obtain a tubular member having a sufficiently high rigidity without increasing the thickness.

Example 1 Example 1 A through hole having a diameter of 5 mm was bored at a rate of 1 per cm ^{2 on} a peripheral wall of a graphite base material having an inner diameter of 9 cm and an outer diameter of 10 cm. This cylindrical base material is loaded into a CVD processing apparatus,
SiCl as a CVD source gas in a state of being heated to 00 ° C.
₄ at a rate of 0.6 / min and C ₃ H ₈ at a rate of 0.1 / min along the inner surface and the outer surface of the tubular substrate, and 0.3 mm thick SiC on both the inner and outer peripheral surfaces of the substrate. A CVD film was formed.

Then, it was taken out of the processing apparatus, the end portion was cut off into a width of 5 mm, and the base material was removed by burning in an atmosphere of 1000 ° C. After the removal of the base material by burning, the peripheral wall through-holes of the obtained double tubular tubular member were filled with graphite powder and charged again into the CVD processing apparatus, and the thickness was 0.1 m under the same processing conditions as above.
m CVD film of SiC was formed on both the inner and outer peripheral surfaces. The obtained product was taken out of the CVD processing apparatus and had an outer diameter of 100.
A tubular member having a diameter of 4 mm, an inner diameter of 89.6 mm and a total length of 390 mm was obtained. The tubular member had a uniform thickness as a whole, and the density of the precipitated SiC was 3.20. When the crystal structure was examined by X-ray diffraction, it was confirmed that the product consisted only of SiC.

[Effects of the Invention] As is clear from the above description, according to the present invention, it is a double cylinder, has high rigidity even when the wall thickness is small, and the constituent ceramic material is dense and highly pure, A tubular member having excellent high temperature strength properties can be obtained. The tubular member obtained according to the present invention consists essentially of the coating film formed by the CVD method, and the base material is removed.
No stress is generated due to the difference in thermal expansion between the D coating and the substrate. Further, according to the present invention, a large-diameter tubular member can be easily manufactured, and a lightweight member having a small wall thickness can also be manufactured.

When the silicon carbide tubular member is produced by the present invention, the obtained tubular member is suitable as a reaction tube for semiconductor production because of its high purity, excellent high-temperature strength, and uniform heat distribution, and a large diameter. Sufficiently applicable to Si wafers. 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 to 5 is an explanatory view showing an example of a method for manufacturing a tubular base material. 1, 2 ... Base material.

Claims (2)

[Claims] 1. A method for producing a hollow double-cylindrical ceramic tubular member, which comprises the following steps to be carried out in sequence. A ceramic coating is formed on both the inner and outer peripheral surfaces of the cylindrical base material having a large number of through holes in the peripheral wall and the inner surface of the through hole by a CVD process, and then the cylindrical base is formed. The material is removed by burning or melting to form a double cylindrical tubular member made of a CVD film having a large number of through holes in its peripheral wall. Further, the through holes are filled with a heat-resistant material, and the double cylindrical tubular member A ceramic coating is formed on the inner peripheral surface and the outer peripheral surface by a CVD process. 2. The method for producing a ceramic tubular member according to claim 1, wherein at least one end of the base material is cut prior to removing the tubular base material in the above step. .