JPS62256715A - Production of chlorosilane - Google Patents

Abstract

PURPOSE:To improve the efficiency in the production of chlorosilanee by crushing silicon in water, and passing gaseous chlorine through the particles to enhance the contact efficiency between the silicon particles and gaseous chlorine. CONSTITUTION:Metallic silicon is charged in a mortar, etc., added with water, and crushed to 1mum-2mm mean particle diameter. The particles are packed in a reaction tube, etc., in a nonoxidizing atmosphere, and heated to evaporate and remove water. Gaseous chlorine is then supplied at 140-300 deg.C, hence chlorine reacts with silicon, and the silicon particles are chlorinated. The formation of by-products is reduced by this method, and chlorosilanes (SinCl2n+2, where n>=2) can be produced with high efficiency.

Description

[Detailed Description of the Invention] Technical Field> The present invention is a method for producing chlorosilane by chlorinating silicon.In recent years, with the development of the electronics industry, the demand for silicon for semiconductors such as polycrystalline silicon or amorphous silicon has increased rapidly. Chlorosilane has recently become particularly important as a raw material for producing silicon for semiconductors.

Chlorosilane can be used as a raw material for producing epitaxial silicon by thermal decomposition as it is, and can also be doped with germanium and used as a silica source for optical fibers.

Chlorosilane is further reduced and converted to silane expressed by the following formula, which is then thermally decomposed to produce silicon for semiconductors or amorphous silicon. For example, disilane Si2H6 is decomposed by thermal decomposition or glow discharge decomposition. An amorphous silicon film is produced. In this case, the deposition rate of +19 formed on the substrate is monosilane SiH4
The silicon film has advantages such as excellent electrical properties, and is expected to see a significant increase in demand in the future as a semiconductor raw material for solar cells.

Traditionally, chlorosilane has been produced by heating metal silicon particles or silicide particles such as calcium silicon, magnesium silicon, or ferrosilicon, supplying chlorine gas, and chlorinating these silicon particles. .

By the way, the above-mentioned conventional methods using silicides such as calcium silicon and magnesium silicon have a problem in that solid by-products such as calcium chloride and magnesium chloride are produced. Furthermore, in the method using metallic silicon, no solid by-product is produced during the reaction with chlorine, but the production rate of chlorosilane is less than 1% on an atomic basis, which is lower than the method using silicide particles. There are significantly fewer problems.

Solution to the Problem> The present inventor has discovered that the reason for the low production rate of chlorosilane in a reaction in which chlorine is passed through metal silicon particles is that the surface of the metal silicon particles is covered with an oxide film, and the oxide film allows chlorine gas and silicon to It was found that this is because contact with particles is prevented.

Based on the above findings, the present invention prevents the formation of an oxide film on the surface of silicon particles, increases the contact efficiency between silicon particles and chlorine gas, and improves the rate of production of chlorosilane.

<Configuration of the Invention> According to the present invention, silicon is pulverized in water to an average particle size of 1 gm or more to 2 mm or less, and then
Chlorosilane (S1nC12C2L) was prepared by passing chlorine gas through the particles at a temperature below 00°C.

However, there is provided a method for producing chlorosilane characterized by producing n≧2).

Further, as a preferred embodiment thereof, there is provided a method for producing chlorosilane in which the particle size of the pulverized silicon is 50 ILm or more and 500 ILm or less, and the temperature at which the chlorine gas is passed is 160°C or more and 260°C or less. A method of making a chlorosilane is provided.

In the present invention, silicon is ground in water. Metallic silicon or the like is used as the silicon element. Further, the preferred purity of silicon is 97% or more.

By pulverizing in water, a non-oxidizing atmosphere is maintained during the pulverization, and formation of an oxide film on the surfaces of silicon particles (hereinafter referred to as silicon particles) is prevented. The average particle size of the pulverized silicon particles is preferably 1 μm or more and 2 mm or less, more preferably 50 gm to 500 gm. If the particle size of the silicon particles is 1 gm or less, dust will be generated during the reaction, which is not preferable. Furthermore, if the particle size exceeds 2 mm, the activity will be poor and the production rate of chlorosilane will decrease. After pulverizing the silicon, the pulverized silicon particles are heated in an inert gas atmosphere or a vacuum atmosphere to evaporate and remove water, etc., and after raising the temperature to 140°C to 300°C, supplying chlorine gas, Chlorinate silicon particles. The amount of chlorine gas supplied varies depending on the amount of silicon particles, etc., but usually silicon 5
Chlorine gas flow% for 0g; 0, 03~3 g/
win, supply time: 1 to 150 hours is sufficient; if the temperature of the chlorination is lower than 140°C, the reaction rate is slow;
On the other hand, if the temperature exceeds 300° C., the production rate of chlorosilane decreases, which is undesirable.SiCl a is produced along with the production of more preferable lucilane, but 5izCJlr is produced by distilling the produced gas.

5i3Cu6 etc. can be easily isolated.

After the chlorination reaction, the generated gas is collected and converted into a base to obtain chlorosilane.

<Effects of the Invention> According to the method of the present invention, silicon particles are crushed in a non-oxidizing atmosphere, so no oxide film is formed on the surface of the particles, and the efficiency of contact between chlorine gas and silicon particles is increased. As a result, the production rate of chlorosilane is significantly improved. Incidentally, in the conventional method using metallic silicon, the production rate of chlorosilane is less than 1% on an atomic basis, but according to the method of the present invention, the production rate is 30% or more, which is significantly higher than the conventional method. High production rates can be achieved.

In addition, in the present invention, since silicides such as magnesium silicide and calcium silicide are not used, the generation of solid by-products such as magnesium chloride and calcium chloride is extremely small.
[Examples and Comparative Examples] Examples and Comparative Examples of the present invention are shown below. The Examples are illustrative of the present invention, and are not intended to limit the scope of the present invention. do not have.

Example 1 50 g of metallic silicon with a purity of 97.5% was placed in an iron mortar, water was added, and the material was ground until the average particle size became 300 μm. Subsequently, the metal silicon particles were filled into a glass reaction tube with an inner diameter of 2 cmφ under a nitrogen gas atmosphere, heated to 300°C to remove water, and then cooled to 200°C, and chlorine gas was added to the tube for 50 minutes.
It was supplied at a rate of 0 m/min and allowed to react for 20 hours. When the generated gas was collected as a condensate, 5iCfL, *,
The amounts of S i2 C16 and S i3 CAB produced were as shown in Table 1.

Comparative Example 1 1 kg of metal silicon was crushed in air to obtain an average particle size of 300.
A chlorination reaction was carried out in the same manner as in Example 1 except that chlorosilane was not substantially produced.

Examples 2 to 4, Comparative Example 2 A chlorination reaction was carried out in the same manner as in Example 1 except that the particle size of the silicon particles was changed. The results are shown in Table 2.

Examples 5 to 7, Comparative Example 3.4 A chlorination reaction was carried out in the same manner as in Example 1 except that the temperature of the chlorination reaction was changed. The results are shown in Table 3.

Example 8 A chlorination reaction similar to that in Example 1 was carried out, and the resulting gas was distilled to isolate S iz CQb and S i3 C1s. The yields were 81 g and 50 g, respectively.

Further, the purity of each of these as measured by gas chromatography was 99.999% or more.

Table 1 Example 2 l 35°23
50 44.6 Table 3

Claims (3)

[Claims] (1) Silicon in water with an average particle size of 1 μm or more to 2 mm
The particles are pulverized as follows, and then chlorine gas is passed through the particles at a temperature of 140°C or higher to 300°C or lower to produce chlorosilane (
A method for producing chlorosilane, characterized by producing SinCl_2_π_+_2, where n≧2). (2) The particle size of the crushed silicon is 50 μm or more or 5 μm or more.
00 μm or less, the manufacturing method according to claim 1. (3) The manufacturing method according to claim 1, wherein the temperature at which the chlorine gas is passed is from 160°C to 260°C.