JPH06127925A - Heat resistant cylindrical body, reaction tube for production of polycrystalline silicon and its production - Google Patents

Abstract

PURPOSE:To provide a heat resistant cylindrical body which can easily be produced as a large-diameter cylindrical body and the process for production of this cylindrical body. CONSTITUTION:This heat resistant cylindrical is the cylindrical body constituted of plural cylindrical body element pieces consisting of heat resistant materials and is formed by joining the gap parts formed between the flanks of the cylindrical body element pieces adjacent to each other by silicon and having a silicon coating layer on the inside surface of the cylindrical body. While a silane compd.-contg. gas is passed under heating in the cylindrical body constituted of the plural cylindrical body element pieces consisting of the heat resistant materials, the silane compd. is thermally decomposed and the silicon formed by the thermal decomposition thereof is deposited in the gap parts in the gap parts formed between the flanks of the cylindrical body element pieces adjacent to each other and is further deposited in a film form on the inside surface of the cylindrical body, by which the cylindrical body is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant cylindrical body, a reaction tube for producing polycrystalline silicon, and a method for producing the same, and more particularly, when producing granular polycrystalline silicon for producing semiconductors by a fluidized bed method. The present invention relates to a heat-resistant cylinder suitable as a fluidized bed reactor used and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, polycrystalline silicon has been mainly produced by a so-called Siemens method in which silicon produced by thermal decomposition of a silane compound such as halogenated silane or monosilane is deposited on a silicon rod. In this method, a silane compound is brought into contact with a silicon rod that has been electrically heated, and silicon produced by thermal decomposition of the silane compound is deposited on the silicon rod. In the case of halogenated silane, the silicon rod is heated to about 1100 to 1200 ° C. by resistance heating, and silicon is deposited on it, but the inner wall of the quartz glass bell jar reactor is cooled to about 300 ° C. Of silicon is prevented. Therefore, the Siemens method is a process in which most of the energy required for heating is lost due to cooling, resulting in large heat loss. In addition, this method has a drawback in that the amount of silicon produced per unit time is small because the deposition area is small, and from this point also the amount of energy consumed per unit amount of silicon produced is large. Furthermore, this method is a batch method in which when a silicon rod becomes thick to a certain extent, it is collected and replaced again with a new one, and therefore equipment has to be increased for mass production, resulting in a large equipment cost. It has the disadvantage.

In order to overcome these drawbacks, a method has been proposed in which a silane compound-containing gas is brought into contact with fluidized silicon particles to deposit silicon on the particles. According to this fluidized bed method, the deposition area is large, the energy cost can be kept low, and since the silicon particles can be continuously produced and recovered, the facility cost can be lowered.

As described above, the production of polycrystalline silicon by the fluidized bed method has an advantage in terms of production cost.
The Siemens method does not directly contact the reaction vessel with silicon, whereas the fluidized bed method has a disadvantage that silicon particles come into direct contact with the reactor and rub against each other, which often causes contamination of impurities. There is a point. The inclusion of impurities not only decreases the yield when producing single crystal silicon from polycrystalline silicon, but also seriously affects the characteristics of semiconductors, and thus cannot provide polycrystalline silicon that can be used for semiconductor applications. there is a possibility.

Therefore, in the production of polycrystalline silicon by the fluidized bed method, various materials have been proposed for the fluidized bed reactor in order to prevent impurities from being mixed into silicon particles. For example, a liner in which the surface of ceramics is coated with silicon is used as a reaction vessel (Japanese Patent Laid-Open No. SHO 6-96).
No. 3-225512), a dense, high-purity silicon carbide sintered body having substantially no porosity is used as a reaction vessel (Japanese Patent Laid-Open No. 62-182162), and the surface of a ceramic base is made high. A reaction tube coated with dense silicon carbide having a purity and a porosity of substantially zero is used (JP-A-62-62).
No. 7620), a reactor made of silicon is used (Japanese Patent Laid-Open No. 64-65010), and a reactor of high-purity graphite coated with high-purity silicon is used (Japanese Patent Laid-Open No. 167811/1990). ), Using a reactor having a gas-impermeable Si ₃ N ₄ film having a film thickness of 10 μm or more on the inner surface of the substrate (Japanese Patent Laid-Open No. 63-117906).

However, there remains a problem that it is difficult to obtain such a reactor having a large diameter. That is, it is difficult to manufacture a large-diameter reactor with a ceramic material, and the larger the diameter, the larger the strain, and the smaller the impact, the more easily it breaks. On the other hand, when trying to manufacture a large-diameter reactor with silicon, there is a disadvantage that the diameter is limited to 150 mm or less due to the size of the material. The large diameter of the reactor is advantageous for efficiently producing polycrystalline silicon.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-resistant cylindrical body which can be easily manufactured as a large-diameter cylindrical body and a manufacturing method thereof.

[0008]

The heat resistant cylindrical body of the present invention comprises:
A tubular body composed of a plurality of tubular element pieces made of a heat-resistant material, wherein voids formed between the side surfaces of the tubular element pieces adjacent to each other are bonded by silicon, and the inner surface of the tubular body is made of silicon. It is characterized by having a coating layer. The tubular element pieces adjacent to each other can be fixed with an appropriate heat-resistant adhesive. As described above, such a heat-resistant cylindrical body is useful as a reaction tube for producing polycrystalline silicon by the fluidized bed method.

On the other hand, the manufacturing method of the heat-resistant cylindrical body of the present invention is as follows.
The silane compound is thermally decomposed while flowing a gas containing the silane compound under heating in a cylinder composed of a plurality of cylindrical element pieces made of a heat resistant material, and the silicon produced by the thermal decomposition is adjacent to each other. It is characterized in that it is deposited in the voids formed between the side surfaces of the tubular element piece, and is further deposited in the form of a film on the inner surface of the tubular body.

The inventors of the present invention have studied the large-diameter heat-resistant cylindrical body and its manufacturing method from various angles. As a result, a plurality of cylindrical element pieces made of the heat-resistant material are arranged in a cylindrical shape. By depositing silicon in the voids formed in the side tube of the tubular element piece to fix them, and by depositing silicon in a film on the inner surface of the tubular body, a large-diameter heat-resistant tubular body can be easily manufactured. I found that I could do it. The present invention has been made based on this finding.

The present invention will be described in more detail below.
FIGS. 1 (a) and 1 (b) show two examples of a heat-resistant cylinder manufactured by using a plurality of cylinder element pieces 1a and 1b made of a heat-resistant material. The cylindrical element pieces 1a, 1b may have any shape, size, etc. as long as a plurality of cylindrical element pieces 1a, 1b can be used to form and maintain the cylindrical body. It is suitable that the diameter of the cylinder is about 50 mm to 2000 mm.

Typical examples of the heat resistant material include silicon and ceramic materials, and specific examples of the ceramic material include SiC, SiC / Si, graphite, alumina, mullite and the like. Metals (Ia group, IIa group, transition metals, etc.) in the ceramics material, B, P,
It is preferable that the impurities such as As that affect the characteristics of the semiconductor are as small as possible. However, even if these impurities are contained, the surface of the polycrystalline silicon is prevented from being contaminated by coating the surface with a silicon film. it can.

In order to produce the heat-resistant cylindrical body according to the present invention, a plurality of cylindrical body element pieces 1a or 1b are arranged so as to form a cylindrical body as shown in FIG. For example, as shown in FIG. 2, fixed inside a stainless steel structural member 2,
The silane compound-containing gas may be supplied into the cylinder while being heated from the outside to the extent that the silane compound introduced into the cylinder is decomposed. By such an operation, silicon is deposited in the void formed between the side surfaces of the tubular element pieces 1a or 1b adjacent to each other, and these tubular element pieces are fixed to each other, and the inner surface of the tubular body is Silicon is deposited in a film form to form a silicon coating layer.

The thickness of the silicon coating layer is 10 μm
It is preferably 20 μm or more. In addition, it is desirable that the total content of the group Ia, the group IIa, and the transition metal be 10 ppb or less and the total content of B, P, and As be 1 ppb or less in the silicon coating layer. This is because these impurities have a particular influence on the characteristics of the semiconductor.

Next, a process for producing polycrystalline silicon using the reaction tube of the present invention will be described with reference to FIG. Inside the fluidized bed reactor 2, the reaction tube 1 for producing polycrystalline silicon of the present invention inserted as a liner is housed.
First, seed silicon particles are charged into the fluidized bed reactor from the introduction pipe 3. Next, the silane compound-containing gas is blown into the fluidized bed reactor 2 from the bottom of the fluidized bed reactor 2 through the gas dispersion plate 5 through the source gas introduction pipe 4 to fluidize the silicon particles on the gas dispersion plate. And then heater 6 for heating
To heat to a specified temperature. The silane compound undergoes thermal decomposition in the fluidized bed, and the produced silicon is deposited on the fluidized silicon particles. Since particles grow due to silicon precipitation and the height of the fluidized bed increases, small seed silicon particles are introduced through the introduction tube 3 to keep the average particle diameter in the fluidized bed constant, and the product is extracted through the extraction tube 7. A part of the silicon particles is extracted to keep the height of the fluidized bed constant. The average particle size of the seed silicon particles is preferably 50 to 300 μm, and the average particle size of the particles in the fluidized bed is preferably 300 to 1500 μm. The reaction temperature is preferably 600 to 800 ° C.

[0016]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 A diameter of 200 mm and a length of 1000 mm shown in FIG.
A tubular body having a thickness of 6 mm was made of 12 silicon tubular element pieces and fixed to the inside of the SUS304 structural material 2 as shown in FIG. The raw material gas was supplied from the gas introduction pipe 4 at a rate of 16 l / min of monosilane and 300 l / min of hydrogen while being heated by the heater 6 so that the inner surface temperature of this cylindrical body was 630 ° C. This operation was stopped after 3 hours. When the cylindrical body 1 was taken out and the degree of deposition of the silicon film on the inner surface thereof was examined, it was found to be coated with a film of about 100 μm. The gap between the silicon tubular element pieces was completely filled with silicon.

Then, using this silicon cylinder as a reaction tube, granular silicon was manufactured by the apparatus shown in FIG.
19K silicon with an average particle size of about 700μm in the reactor
g charge, hydrogen gas 480 l / min, monosilane gas 1
16 l / min was introduced from the raw material gas inlet 4. The particle temperature was maintained at 670 ° C. by the heater 6. 140 g of silicon with an average particle size of 200 μm from the seed silicon introduction tube 3
The product silicon particles were withdrawn at a rate of 6.9 Kg / hour at intervals of 5 minutes from the extraction tube 7 while being introduced at a rate of / hour. The product silicon particles were cooled in an extraction tube, and then received in Teflon bin which had been thoroughly washed with acid and washed with pure water.

Example 2 A diameter of 300 mm and a length of 1500 as shown in FIG.
A tubular body of mm was made of 36 tubular element pieces made of SiC, and silicon coating was performed in the same manner as in Example 1 to produce a reaction tube. Using this, polycrystalline silicon was manufactured in the same manner as in Example 1. When the impurity analysis of the product silicon particles after 10 hours was performed, almost the same results as in Example 1 were obtained.

The impurity analysis of the obtained product silicon was conducted as follows. For metals, HF / HN
The solution after removing the silicon with O ₃ is ICP-MS,
It was analyzed using the atomic absorption method. F for B, P and C
After crystallization by the Z method, it was measured using FT-IR.
The impurities in the product silicon after operating for 10 hours and 100 hours were the values shown in Table 1.

[0021]

[Table 1]

[0022]

According to the inventions of claims 1 and 3, a heat-resistant cylindrical body having a large diameter is used, and if this is used in a fluidized bed reactor for producing polycrystalline silicon, improvement in productivity can be expected. According to the invention of claim 2, a large-diameter heat-resistant cylindrical body (useful as a fluidized bed reactor for producing polycrystalline silicon) is easily manufactured.

[Brief description of drawings]

1A and 1B are schematic perspective views of two examples of a heat-resistant cylindrical body useful as a reaction tube for producing polycrystalline silicon according to the present invention.

FIG. 2 is a schematic view showing an example of a fluidized bed reactor for carrying out the polycrystalline silicon of the present invention.

[Explanation of symbols]

 1 liner (reaction tube) 2 fluidized bed reactor 3 type silicon particle introduction tube 4 raw material gas introduction tube 5 gas dispersion plate 6 heating heater 7 product silicon particle extraction tube 8 waste gas discharge tube

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazutoshi Takatsuna 3-1, Chidori-cho, Kawasaki-ku, Kanagawa Prefecture Tonen Kagaku Co., Ltd. Technology Development Center (72) Inventor Yasuhiro Saruwatari Chidori, Kawasaki-ku, Kawasaki-shi, Kanagawa Town No. 3-1, Tonen Kagaku Co., Ltd. Technical Development Center (72) Inventor Nobuhiro Ishikawa 1 in the first place of Funami-cho, Minato-ku, Aichi Prefecture Nagoya City Toagosei Chemical Industry Co., Ltd. Nagoya Research Institute (72) Invention Person Hirohiro Tasuke 23 Nagoya Toagosei Chemical Industry Co., Ltd., 23, Showa-cho, Minato-ku, Nagoya City, Aichi Prefecture

Claims (3)

[Claims] 1. A tubular body composed of a plurality of tubular body element pieces made of a heat resistant material, wherein voids formed between side surfaces of mutually adjacent tubular body element pieces are joined by silicon. A heat resistant cylindrical body having a silicon coating layer on the inner surface of the cylindrical body. 2. A silicon body produced by the thermal decomposition of a silane compound while the silane compound-containing gas is being circulated under heating in a cylinder composed of a plurality of cylindrical element pieces made of a heat-resistant material. Is deposited in the voids formed between the side surfaces of the tubular element pieces adjacent to each other, and is further deposited in the form of a film on the inner surface of the tubular body. 3. A reaction tube for producing polycrystalline silicon, which comprises the cylindrical body according to claim 1.