JPH06127917A - Production of high-purity silicon pipe - Google Patents

Abstract

PURPOSE:To provide a high-purity silicon pipe having sufficient strength in a short period of time by thermally decomposing a silane compd. while passing the silane compd. in a high-purity silicon particle layer packed into the annular spacing between the inside pipe and outside pipe of double pipes thereby depositing silicon as a binder, CONSTITUTION:The inside pipe 2 and the outside pipe 3 are inserted and fixed into a cylindrical reactor 1. The high-purity silicon particles 4 having 100 to 1000mum grain sizes are packed into the annular spacing formed between two pieces of these pipes. Graphite, quartz or the composite materials composed thereof are used for the materials of the inside and outside pipes and are washed with high-purity hydrofluoric acid at the time of use. The inside and outside pipes are then heated by an external heater 5 and the silane compd. (e.g.: trichlorosilane)-contg. gas is introduced from an introducing pipe 6 and is flowed upper side to thermally decompose the silane compd. and to deposit the silicon. The silicon pipe integrally stuck with the silicon particles is thus formed. Gaseous hydrogen, etc., are used as the diluting gas. The concn. of the silane compd. is specified to about 10 to 60vol.% and the heating temp. to about 950 to 1250 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-purity silicon tube, and more particularly, to a method for producing granular polycrystalline silicon by thermal decomposition of a silane compound in a fluidized bed reactor, which is used in the reactor. The present invention relates to a method for producing a high-purity silicon tube which is useful as a liner for preventing contamination of silicon particles used.

[0002]

2. Description of the Related Art The production of high-purity polycrystalline silicon for semiconductors is mainly carried out by the Siemens method. This is to install a silicon rod in a bell jar type reactor, heat it by energizing it, let a mixed gas of trichlorosilane and hydrogen flow, and deposit the silicon produced by the reaction on the silicon rod. . Although this method is suitable for the production of high-purity silicon, it has low productivity due to its small reaction surface area, it consumes a large amount of heat from the bell jar surface, and consumes a large amount of electricity. Each time, the silicon rod must be recovered and the reaction must be stopped in order to replace it with another new one.

On the other hand, a fluidized bed method has recently been attracting attention as an energy-saving method for producing polycrystalline silicon (Japanese Patent Publication No. 35-18555 and Japanese Patent Laid-Open No. 57-13).
5708, etc.). In this method, the silicon particles are fluidized in the reactor, and silicon produced by thermal decomposition of a silane compound such as chlorosilane gas or monosilane introduced into the reactor is deposited on the surface of the silicon particles to form granular particles. Is a method for producing silicon particles. In this method, since the reaction is performed on the surface of the particles, there are advantages that the reaction area is large, the productivity is high, and the continuous process is possible.

In the above fluidized bed method, since the fluidized high temperature silicon particles violently contact the inner wall of the reactor, impurities are mixed into the silicon particles from the reactor wall, and high-purity silicon particles suitable for use in semiconductors are obtained. There was a problem that could not be obtained. Therefore, conventionally, a high-purity quartz tube or silicon carbide tube containing almost no metal impurities or electrically active impurities was installed as a liner in the reactor, or the reactor itself was made of these high-purity materials. The method of suppressing the mixture of impurities as much as possible has been adopted.

Further, a heating heater installed outside the reactor is usually used to heat the particles in the fluidized bed to the reaction temperature. Therefore, the inner wall of the reactor (the liner when using the liner) has a temperature higher than that of the fluidized bed itself, and the thermal decomposition reaction of the silane compound occurs preferentially to cause silicon deposition on the inner wall. In such a reactor in which silicon is deposited on the inner wall, a large thermal stress is generated at the time of heating or cooling due to the difference in thermal expansion coefficient between the material used for the reactor and silicon, and damage to the reactor may occur. It can be a cause. Furthermore, recently, the demand for the quality of polycrystalline silicon has become more severe, and even impurities at a level mixed from a quartz tube, a silicon carbide tube, or the like have become a problem. There is an increasing desire to use silicon tubing.

In order to meet such a demand, tubular graphite is heated by energization to deposit a semiconductor material from a gaseous compound on the graphite,
A method for manufacturing a tube made of a semiconductor material has been proposed (JP-A-2-6315). However, with such a method, although it is possible to manufacture a high-purity silicon tube, the silicon deposition rate is very low, and it is very large to obtain a silicon tube having a thickness with practically sufficient strength. There is a problem that it takes time.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method capable of producing a high-purity silicon tube having a wall thickness which has practically sufficient strength in a short time.

[0008]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems.

That is, according to the present invention, the silane compound is pyrolyzed while flowing the silane compound through the high-purity silicon particle layer filled in the annular gap between the inner tube and the outer tube of the double tube. Thus, a method for producing a high-purity silicon tube is provided, in which silicon as a binder is deposited in the silicon particle layer and the silicon particle layer is integrally fixed.

The manufacturing method of the high-purity silicon tube of the present invention is as follows.
Instead of creating a tube only by depositing silicon, the high-purity silicon particles are filled in the annular gap formed between the inner tube and the outer tube of the double tube, and the silicon thus formed is formed. This is a method in which a silane compound is allowed to flow through the particle layer, and the silane compound is thermally decomposed during that time to be deposited on the silicon particle layer, and the deposited silicon is used as a binder to integrally fix the silicon particle layer. According to the present invention, a thick high-purity silicon tube having sufficient strength can be obtained in a short time.

Hereinafter, the method of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an outline of a reactor used for carrying out the present invention. In the reactor shown in FIG. 1, an inner tube 2 and an outer tube 3 are inserted and fixed in a cylindrical reactor 1.
In the present invention, the high-purity silicon particles 4 are packed in the annular gap formed between the two tubes. The materials of the inner tube and the outer tube are preferably as pure as possible in order to suppress contamination of the silicon particles, and are preferably those that can be easily removed even if they are fixed to the silicon particles. . Particularly preferred materials include, for example, graphite, quartz or composite materials thereof. The inner cylinder 2 and the outer cylinder 3 to be inserted into the reactor 1 are preferably washed with high-purity hydrofluoric acid or the like in order to remove contaminants adhering to the surfaces thereof during use. Further, the high-purity polycrystalline silicon particles used here are preferably high-purity ones at least as high as the target product silicon for the purpose of preventing contamination of the product silicon when used as a liner. . Considering the ease of handling and the filling rate into the annular space of the double tube, the particle size of silicon is 10
0 to 1000 μm is preferable.

The silicon particles filled in the annular gap of the double tube are heated by the external heater 5 in FIG. 1, but heating may be performed by disposing the heater inside the inner tube 2. Alternatively, it may be performed by heating both the inner and outer cylinders. The silane compound-containing gas is introduced from the introduction pipe 6 into the annular gap between the inner pipe 2 and the outer pipe 3 filled with the silicon particles 4, and is circulated upward in this gap, during which the silane compound is thermally decomposed. Let As the silane compound, for example,
Trichlorosilane, monosilane, disilane, etc. are used. The thermal decomposition temperature of the silane compound is, for example, 950 to 1250 ° C. in the case of trichlorosilane, 580 to 750 ° C. in the case of monosilane, and 50 in the case of disilane.
Preference is given to using heating temperatures of 0 to 600 ° C. As the diluting gas, hydrogen gas is used in the case of trilychlorosilane, and hydrogen gas and / or an inert gas (argon, helium, etc.) is used in the case of monosilane or disilane. The silane compound concentration in the silane compound-containing gas is appropriately determined according to the type of the silane compound. For example, in the case of trichlorosilane, 10-60 vo
1%, preferably 20 to 50 vol%, in the case of monosilane, 0.1 to 50 vol%, preferably 1 to 10 vol
%, And in the case of disilane, it is preferable to set it in the range of 0.1 to 30 vol%, preferably 1 to 10 vol%. The flow rate of the silane compound-containing gas is a speed at which the silicon particles filled in the annular void do not fluidize, and is usually 15 cm / sec or less, preferably 1 to 10 cm / sec. As described above, when the silane compound-containing gas is circulated through the silicon particle layer 4 formed in the annular space between the inner cylinder 2 and the outer cylinder 3 under heating, the silane compound is on the silicon particle layer. The silicon undergoes thermal decomposition to produce silicon, which is deposited on the silicon particle layer. The precipitated silicon acts as a binder to fix the silicon particles to each other, and the annular space between the inner cylinder 2 and the outer cylinder 3 is
A silicon tube is formed in which silicon particles are integrally fixed. The silicon tube thus formed has an inner cylinder 2
And the outer cylinder 3 is removed from the silicon tube to be recovered as a product silicon tube. The removal of the inner cylinder and the outer cylinder from the silicon tube can be appropriately performed depending on the materials of the inner cylinder and the outer cylinder. For example, when the inner cylinder and the outer cylinder are made of a flammable material such as graphite, they can be removed from the silicon tube by incineration. When the inner and outer cylinders are made of quartz, or a material such as silicon carbide, silicon nitride, or alumina, which has a coefficient of thermal expansion different from that of silicon, heat shock due to heating and cooling is applied to the silicon tube. Can be removed from. Further, when the inner cylinder and the outer cylinder are made of quartz, they can be removed by dissolving the quartz with hydrofluoric acid.

[0014]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 According to the embodiment shown in FIG. 1, an inner diameter of 100 mm and a height of 1200
mm outer diameter 96 mm, inner diameter 90 mm, height 1000 mm graphite outer tube, outer diameter 80 mm,
A graphite inner tube having an inner diameter of 74 mm and a height of 1000 mm was concentrically provided, and 1.6 kg of granular silicon having a particle diameter range of 100 to 1000 μm and an average of 500 μm was packed in an annular gap between the outer tube and the inner tube. The particles were heated by an external heater to 1000 ° C., and trichlorosilane 2.0 g / min. , Hydrogen 560 cm ³ / min. In 4
It was introduced for 0 hours. After cooling, when the graphite double tube was taken out from the reactor, the graphite tube was stuck to the silicon particles, so graphite was burned and removed in the furnace and washed with hydrofluoric acid to a thickness of 5 mm and height. 1000
A mm silicon tube was obtained.

The silicon tube thus obtained was used as a liner to produce silicon particles by hydrogenolysis of trichlorosilane in a fluidized bed. The impurity concentration in the product obtained was such that the total metal impurities was 1 wtppb.
Hereinafter, carbon was 0.1 ppma or less.

Example 2 The gas introduced was monosilane 100 cm ³ / min. ,
Hydrogen 2500 cm ³ / min. And the particle temperature is 6
A silicon tube was manufactured under the same conditions as in Example 1 except that the temperature was set to 00 ° C. After reacting for 40 hours and cooling,
When the graphite double tube was taken out of the reactor, the graphite tube was firmly fixed to the silicon particles. Therefore, the graphite was burned and removed in the furnace and washed with hydrofluoric acid to obtain a silicon tube.

When the silicon tube thus obtained was used as a liner to produce silicon particles by hydrogenolysis of trichlorosilane in a fluidized bed, the impurity concentration in the product obtained was such that the total metal impurities was 1 wtppb.
Hereinafter, carbon was 0.1 ppma or less.

Example 3 The gas to be introduced was disilane 50 cm ³ / min. , Hydrogen 2500 cm ³ / min. And the particle temperature is 550
A silicon tube was manufactured under the same conditions as in Example 1 except that the temperature was changed to ° C. After reacting for 40 hours and cooling, after taking out from the reactor together with the graphite double tube, the graphite tube was fixed to the silicon particles, so the graphite was burnt and removed in the furnace and washed with hydrofluoric acid, A silicon tube was obtained.

The silicon tube thus obtained was used as a liner to produce silicon particles by hydrogenolytic decomposition of trichlorosilane in a fluidized bed. As a result, the impurity concentration in the product obtained was such that the total metal impurities was 1 wtppb.
Hereinafter, carbon was 0.1 ppma or less.

Example 4 A quartz tube having an outer diameter of 97.5 mm, an inner diameter of 91.5 mm and a height of 1000 mm was used as the outer tube, and an outer diameter of 8 mm was used as the inner tube.
A silicon tube was manufactured under the same conditions as in Example 1 except that a quartz tube having a diameter of 0.5 mm, an inner diameter of 74.5 mm and a height of 1000 mm was used. After cooling, when the quartz double tube was taken out from the reactor, the quartz tube was fixed to the silicon particles, but during cooling, most of it peeled off due to thermal stress. The quartz tube was removed by dissolving some of the remaining quartz with hydrofluoric acid, and washed again with hydrofluoric acid to obtain a silicon tube.

The silicon tube thus obtained was used as a liner to produce silicon particles by hydrogenolysis of trichlorosilane in a fluidized bed. The impurity concentration in the product obtained was such that the total metal impurities was 1 wtppb.
Hereinafter, carbon was 0.1 ppma or less.

[0023]

According to the method for producing a high-purity silicon pipe of the present invention, a thick high-purity silicon pipe having sufficient strength can be easily obtained in a short time. This high purity silicon tube is advantageously used as a liner in a fluidized bed reactor to obtain granular polycrystalline silicon.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of a reactor for carrying out the present invention.

[Explanation of symbols]

 1 Cylindrical reactor 2 Inner tube 3 Outer tube 4 High-purity silicon particles 5 External heater 6 Gas introduction tube

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Ishii 3-1, Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Tonen Chemical Co., Ltd. Technical Development Center (72) Inventor Kazutoshi Takazuna Chidori, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 3-1, Tonen Kagaku Co., Ltd. Technology Development Center (72) Inventor Yasuhiro Saruwatari 3-1, Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Tonen Kagaku Co., Ltd. (72) Inventor Nobuhiro Ishikawa One of the first place in Funami-cho, Minato-ku, Nagoya-shi, Aichi Prefecture Toagosei Synthetic Chemical Industry Co., Ltd. Nagoya Research Institute (72) Inventor ▲ Hirota Tasuke 23 Toagosei-Chemical Chemistry, 17 Showa-cho, Minato-ku, Nagoya-shi, Aichi Prefecture Industry Co., Ltd. Nagoya factory

Claims (2)

[Claims] 1. A silicon particle layer obtained by thermally decomposing a silane compound while allowing the silane compound to flow through a high-purity silicon particle layer filled in an annular gap between an inner tube and an outer tube of a double tube. Precipitate silicon as a binder inside,
A method for producing a high-purity silicon tube, which comprises integrally fixing a silicon particle layer. 2. The method for producing a high-purity silicon pipe according to claim 1, wherein the material of the double pipe is high-purity graphite, quartz or a composite material thereof.