JPS62108726A - Method and apparatus for producing high-purity silicon - Google Patents

Abstract

PURPOSE:To inexpensively produce high-purity silicon by utilizing SiCl4 and H2 which are by-produced by decomposition of trichlorosilane for the production of both silicon-contg. metal and a fine metallic grain. CONSTITUTION:High-purity silicon, SiCl4 and H2 are obtained by decomposing trichlorosilane. SiCl4 is accompanied with gaseous Ar 9 through a tank 8 held in the inside of an isothermal tank 7 and introduced into a high-temp. furnace 5 and allowed to react with a metallic sheet 6 passing through the inside of the furnace 5 to obtain silicon-contg. metal, metallic chloride and hydrogen chloride. This metallic chloride is accompanied with gaseous Ar 15 through a tank 13 and introduced into a high-temp. furnace 12 and allowed to react with the above-mentioned gaseous H2 fed through a pipe 17 to obtain fine metal grin and hydrogen chloride. The above-mentioned hydrogen chloride is allowed to react with crude silicon to obtain trichlorosilane.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for producing high-purity silicon by decomposing trichlorosilane, and particularly to a reduction in the production cost of high-purity silicon.

[Conventional technology]

Large amounts of high-purity silicon are used in integrated circuits, solar cells, etc. This high-purity silicon is produced by refining crude metal silicon. The chloride purification method is known as a method for refining high purity silicon from crude metal silicon.
Among the chloride purification methods, the Siemens method is the mainstream of this purification method.

Siemens method (well, crude metal silicon is reacted with hydrochloric acid to produce trichlorosilane (S i HCl), and this trichlorosilane is decomposed to obtain high purity silicon.

[Problem that the invention seeks to solve]

In the Siemens method described above, trichlorosilane is decomposed into silicon, silicon tetrachloride (SiC14), and hydrogen to obtain high-purity silicon, so the yield of high-purity silicon obtained is less than 40% of that of crude metal silicon. Yes, most of the silicon content turns into silicon tetrachloride. -If this by-produced silicon tetrachloride has a high utility value, the manufacturing cost of high-purity silicon can be reduced for the entire process, but the uses of this silicon tetrachloride are limited, and currently it is a low-priced product. It is only used as a raw material for silica (Sin2). Therefore, the Siemens method as described above has a problem in that it cannot further reduce the manufacturing cost of high-purity silicon.

The present invention has been made to solve these problems, and aims to provide a method and apparatus that can reduce the manufacturing cost of high-purity silicon.

[Means for solving problems]

The method for producing high-purity silicon according to the present invention involves decomposing I-lichlorosilane to obtain high-purity silicon, and reacting silicon tetrachloride, which is produced as a by-product during the decomposition, with a metal in the third method for producing high-purity silicon. to obtain a silicon-containing metal, react the metal chloride produced as a by-product during this reaction with the hydrogen generated during the decomposition to obtain metal fine particles, and remove the hydrogen chloride produced as a by-product during the reaction and the silicon-containing metal to obtain the metal microparticles. The above-mentioned trichlorosilane is produced by reacting hydrogen chloride produced as a by-product during the reaction with crude silicon.

Further, the high-purity silicon manufacturing apparatus according to the present invention includes a trichlorosilane decomposition apparatus that decomposes trichlorosilane into high-purity silicon, silicon tetrachloride, and hydrogen, and a silicon-containing metal that reacts the silicon tetrachloride with a metal. a CVD silicon extrusion device for producing hydrogen chloride, a metal chloride, and hydrogen chloride; a metal fine particle manufacturing device for producing metal fine particles and hydrogen chloride by reacting the metal chloride with the hydrogen; and a trichlorosilane production apparatus for producing the trichlorosilane by reacting hydrogen chloride obtained in the metal fine particle production apparatus with crude silicon.

[Effect]

In this invention, silicon tetrachloride and hydrogen by-produced by the decomposition of trichlorosilane are used to produce silicon-containing metals, hydrogen to produce metal fine particles, and silicon-containing metals. Hydrogen chloride produced as a by-product in the production of trichlorosilane and the production of metal fine particles is used to produce trichlorosilane.

〔Example〕

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and as shown in this diagram, the method according to the present invention includes a trichlorosilane decomposition step [1] and a CvD (chemical vapor deposition) silicon extrusion step. (2), a metal fine particle manufacturing process (3), and a trichlorosilane manufacturing process (4).

In the trichlorosilane decomposition step (1), trichlorosilane is decomposed to obtain high purity silicon, silicon tetrachloride, and hydrogen.

The present inventors have conducted research on silicon exfoliation using the CVD method. For example, by exfoliating an iron alloy with silicon tetrachloride, which is a by-product of the trichlorosilane decomposition process, using the CVD method, a soft magnetic material with excellent AC magnetic properties can be obtained. I have come to the knowledge that it is possible.

Therefore, after the trichlorosilane decomposition step (1), CVD
A bleed silicon step (2) is provided, and a trichlorosilane decomposition step (1) is provided.
) and reacted with the metal to obtain a silicon-containing metal and a metal chloride.

Taking iron as an example, the basic reaction when using silicon tetrachloride is 5Fe+5iC14→Fe3Si+2FeCI2.

Silicon-containing alloys obtained in the CVD silicon extrusion process (2) include 3-65% Sl steel, Sendust (Fe-5i-A
4 alloy), Super Sendust (Fe-3i -A/-
Ni alloy), Fe-Co-3i alloy, Mo-3i alloy, W-Si alloy, Ni-5i alloy, Co-3i alloy, etc.

FIG. 2 shows a CVD silicon extrusion apparatus for carrying out the CVD silicon extrusion method. In this figure, (5) is a high temperature furnace, (6)
is a metal sheet that is heated and passed through this high-temperature furnace,
(7) is a constant temperature bath, (8) is a silicon tetrachloride bath held in this constant temperature bath, and (9) is a silicon tetrachloride bath held in this bath.
"Ar gas blowing pipe (10) is a silicon tetrachloride blowing pipe for blowing silicon tetrachloride expelled from the silicon tetrachloride tank (8) into the high temperature furnace (5) by this Ar gas, (11) is a high temperature furnace (5
) is an exhaust gas discharge pipe that guides the exhaust gas inside the exhaust gas to the exhaust gas treatment equipment.

When silicon is exuded by this CVD method, as a metal chloride,
Since the trichlorosilane decomposition process (11) uses metal chloride as a by-product, it is possible to reduce the manufacturing cost of high-purity silicon.

Next, as is clear from the above reaction equation, 10 to 30% of the supplied iron becomes ferrous chloride gas, and the yield of iron decreases. Therefore, the present inventors conducted studies with the aim of recovering iron, and arrived at the knowledge that iron fine particles and hydrochloric acid can be obtained by reacting ferrous chloride gas with hydrogen gas, and the metal fine particle production process (3) was established.

A problem in this step (3) is that the cost of hydrogen, which is a reducing gas, is high. However, since hydrogen was produced as a by-product in the trichlorosilane decomposition step (1), it was decided to use this hydrogen in the metal fine particle production step (3).

That is, in the metal fine particle manufacturing step (3), metal chloride produced as a by-product in the CVD silicon extrusion step (2) is reacted with hydrogen generated in the trichlorosilane decomposition step (1) to obtain metal fine particles.

Examples of the metal fine particles obtained in the metal fine particle production step (3) include Fe, MoSW, Ni, Coya particles, and alloy fine particles thereof.

FIG. 3 shows a metal fine particle manufacturing apparatus for carrying out this metal fine particle manufacturing method. In this figure, (1 is a high-temperature furnace, fl, m is a metal chloride tank, (group is a heater that heats this metal chloride tank, (lcil is a metal chloride tank (l) is an Ar gas for blowing Ar gas into The blowing pipe (1Q) transfers the metal chloride discharged by this Ar gas to a high-temperature furnace (1Q).
Metal chloride injection pipe to blow into 1J (1 is a hydrogen gas injection pipe for blowing hydrogen gas into high temperature furnace (1), (formerly used to collect metal fine particles generated in high temperature furnace) It is a metal particulate collection device that
Hydrochloric acid gas generated within 1η is led to a hydrochloric acid gas treatment device.

In the step (4) of producing I.lichlorosilane, hydrochloric acid is required to convert crude silicon into trichlorosilane. However, the metal fine particle manufacturing process (3) and the CVD silicon extrusion process (
In 2), hydrogen chloride is produced as a by-product. If the hydrogen chloride produced as a by-product in the metal fine particle production process (3) and the CVD silicon extrusion process (2) is used in the trichlorosilane production process (4), the production costs for both can be further reduced significantly, and as a result,
The manufacturing cost of high-purity silicon can be lowered.

Therefore, in the trichlor 7-run manufacturing process (4), 1. t, hydrogen chloride and CVD produced as by-products in the metal fine particle manufacturing process (3)
The above-mentioned trichlorosilane is obtained by reacting the hydrogen chloride produced as a by-product in the silicon exfoliation step (2) with the crude silicon.

Various types of apparatus for producing trichlorosilane can be considered, and an apparatus for producing trichlorosilane by reacting crude silicon with hydrochloric acid using a fluidized bed may also be used.

Experimental Example The case where the manufacturing cost of high-purity silicon is the lowest will be shown below in an experimental example. An example will be explained in which 3% 51w4 is supplied to produce high purity silicon, 6.5% Si steel plate, and Fe ultrafine particles.

High purity silicon was manufactured using the Siemens method using 3.333 kg of tum gold i-silicon. At this time, fal high purity silicon 1 kg (bl hydrogen gas
0.333 kgfc) Hydrochloric acid
1.3 kg (di 5iC1414, 16 kg was generated).

80.3 kg of 3% Si steel plate @CVD silicon exfoliation equipment (dl
5iC14 (e16, 5% Si steel plate 73.7 kg (f)
221.6 kg of F e Cl were obtained.

[fl of FeCl2 and (bl of hydrogen gas 0.333 k
By reacting with g and t Kokoro (gl Iron fine particles 9.77 kg (h)
12.16 kg of hydrochloric acid was obtained.

When the thl hydrochloric acid was combined with the hydrochloric acid (c), almost the amount required for the production of trichlorosilane could be obtained.

However, since there was some loss in each step, it was necessary to add about 0.3 kg of hydrochloric acid.

〔Effect of the invention〕

As explained above, the present invention utilizes silicon tetrachloride and hydrogen by-produced by the decomposition of trichlorosilane to produce silicon-containing metals and metal fine particles, and also uses silicon-containing metals and metal fine particles to manufacture silicon-containing metals and metal fine particles. Hydrogen chloride produced as a by-product is used to produce trichlorosilane, and all substances produced as by-products in each process are used in a closed cycle, reducing the cost of producing high-purity silicon. There is an effect.

[Brief explanation of drawings]

Figure 1 is a process diagram showing one embodiment of this invention, and Figure 2 is a C
FIG. 3 is an explanatory diagram of a VD silicon extrusion apparatus, and FIG. 3 is an explanatory diagram of a metal fine particle manufacturing apparatus. In the figure, (1) is the trichlorosilane decomposition process, (2
) is a CVD silicon extrusion process, (3) is a metal fine particle manufacturing process, (
4) is the trichlorosilane manufacturing process. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In a method for producing high-purity silicon in which high-purity silicon is obtained by decomposing trichlorosilane, silicon-containing metal is obtained by reacting silicon tetrachloride, which is a by-product during this decomposition, with a metal, and The metal chloride is reacted with the hydrogen generated during the decomposition to obtain metal fine particles,
Production of high-purity silicon, characterized in that the trichlorosilane is produced by reacting hydrogen chloride produced as a by-product during the reaction to obtain the metal fine particles and hydrogen chloride produced as a by-product during the reaction to obtain the silicon-containing metal with crude silicon. Method. (2) a trichlorosilane decomposition device that decomposes trichlorosilane into high-purity silicon, silicon tetrachloride, and hydrogen;
a CVD silicon extrusion device for reacting the silicon tetrachloride and a metal to obtain a silicon-containing metal, a metal chloride, and hydrogen chloride;
A metal fine particle manufacturing apparatus which reacts the metal chloride and the hydrogen to obtain metal fine particles and hydrogen chloride, and hydrogen chloride obtained by the CVD silicon extrusion apparatus and hydrogen chloride obtained by the metal fine particle manufacturing apparatus. A high-purity silicon production apparatus comprising a trichlorosilane production apparatus for producing the trichlorosilane by reacting it with crude silicon.