JPS62143814A - Production of chlorosilane - Google Patents

Abstract

PURPOSE:To produce chloropolysilane in high yield without forming solid by- products, by pulverizing silicon particles in an inert organic solvent and chlorinating the pulverized particles at a high temperature. CONSTITUTION:Silicon particles, preferably having 50mu-2mm average particle diameter are pulverized in an inert organic solvent, e.g. dodecane or trichloroethylene, etc., and the pulverized particles are then chlorinated at a high temperature, preferably 140-300 deg.C to produce the aimed chloropolysilane [SinCl2n+2 (n is >=3)]. According to this method, the polychlorosilane can be produced without forming by-products as in a conventional case where an alloy of a metal with silicon is subjected to chlorination reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing polychlorosilane by chlorinating silicon.

In recent years, with the development of the electronics industry, the demand for semiconductor silicon such as polycrystalline silicon or amorphous silicon has increased rapidly, and polychlorosilane has recently become particularly important as a raw material for manufacturing such semiconductor silicon. There is.

Of course, polychlorosilane can be thermally decomposed as it is to produce epitaxial silicon or the like, but it is also used as a silica source for optical communications with a high germanium doping rate. In addition, chlorosilane is further reduced to silane expressed by the formula (JT), and 5inHzn+z (n≧:3)
(II) This is usually thermally decomposed to produce silicon for semiconductors or amorphous silicon. For example, when disilane, 5i2IIG, is used to form an amorphous silicon film by thermal decomposition or glow discharge decomposition, the rate of deposition on the substrate is much higher than that of monosilane, 5il14, and the film is It has advantages such as excellent electrical properties, and demand is expected to increase significantly in the future as a raw material for semiconductors for solar cells.

[Conventional technology]

Conventionally, chloropolysilane has been obtained through a chlorination reaction by heating an alloy of metal and silicon such as calcium silicon, magnesium silicon, or ferrosilicon, or silicon particles and feeding chlorine gas.

[Problem that the invention seeks to solve]

When producing chlorosilane using conventional methods, solid by-products such as calcium chloride and magnesium chloride are produced.
A commercial manufacturing method that does not generate solid by-products is desired.

Furthermore, although no solid by-products are observed in the reaction between silicon particles and chlorine, the production rate of veglorosilane is extremely low at less than 1% based on silicon atoms compared to the method using 1 alloy, which is a problem.

[Points of focus and knowledge related to solving the problem] The present inventor has studied the possibility of providing a method for producing chloropolysilane that does not generate solid by-products due to the reaction between silicon and chlorine and has a high yield. As a result, the surface of silicon is oxidized very quickly, so the silicon surface is generally covered with an oxide film, and once the oxide film is formed, it becomes less reactive, so it is difficult to react with silicon and chlorine. The present invention was achieved by discovering that the yield of chlorosilane was extremely low.

[Structure of the invention]

According to the present invention, there is provided a method for producing chlorosilane (SinC1z n+z, where n≧3), which comprises pulverizing silicon particles in an inert organic solvent and chlorinating the pulverized particles at high temperature.

According to this method, chlorosilane can be obtained in a higher yield by reacting at a lower temperature than conventionally. This is because the surface of the silicon grains is not oxidized and always maintains a new surface due to the grinding using an inert solvent, which increases the activity.

According to the present invention, the recovery rate of chlorosilane, which was conventionally less than 1% based on silicon atoms, has been improved to more than 30%.

The higher the purity of the silicon used in the method of the present invention, the less solid by-products will be produced. Purity is a matter to be determined taking this into account, but 97% or more is desirable.

In the method of the present invention, the average particle size of silicon particles is 50 μm.
2mm or less, and chlorination is 140℃ or more and 30℃ or more.
It is desirable to carry out the process at a temperature below 0°C. If the average particle size of the silicon particles is larger than 211II11, the activity will be poor and the production rate of chlorosilane will decrease, which is preferable. If it is smaller than 50 μm, dust will be generated during the reaction, which is also not preferable.
If the chlorination temperature is lower than 140°C, the reaction rate is too slow, which is unsuitable; if it exceeds 300°C, the production rate of chlorosilane decreases, which is also unsuitable.

In the present invention, the inert organic solvent is a solvent that does not react with silicon, and is not particularly limited, but has a low evaporation rate during the pulverization process, and is a solvent that does not react with silicon particles, and is a solvent that does not react with silicon. Inert hydrocarbons such as dodecane, nonane, octane, and toluene, as well as carbon tetrachloride and tetrachloroethylene, are required to have high vapor pressure.

Chlorinated hydrocarbons such as trichlorethylene may be mentioned.

〔Effect of the invention〕

According to the present invention, there is no generation of solid by-products that are unavoidable during chlorination reactions of calcium and silicon alloys, and it is also possible to omit the process of adjusting the alloy.
Chlorosilane can be obtained in high yield through the chlorination reaction of silicon.

Next, the present invention will be explained more specifically by examples.
The following examples are not intended to limit the scope of the invention.

〔Example〕

Example 1 50 mQ of dodecane was added to 50 g of silicon with a purity of 97.5%, and the mixture was ground using an iron mortar until the average particle size became 300 μm, and the mixture was filled into a glass reaction tube with an inner diameter of 2 cm.

After heating to 300°C to remove remaining dodecane, the temperature was lowered to 200°C, chlorine gas was introduced at a rate of 50 mQ/min, and the reaction was carried out for 20 hours. collecting the product as a condensate;
When analyzed by gas chromatography, 5iC14,
Si, C1,t The amount of Si, C1, is 61g each,
82g.

It was 55g.

Example 2 1.2 M of toluene was added to 1 kg of the same silicon, and the mixture was pulverized until the average particle size became 400 μI, and the mixture was filled into a glass reaction tube with an inner diameter of 1 Oal. After heating to 250°C to remove remaining toluene, the temperature was lowered to 200°C, chlorine gas was introduced at a rate of 1.30/min, and the reaction was carried out for 20 hours. The product was collected as a condensate and analyzed by gas chromatography to give 5iC14,SL,C1.

The amount of 5i3C111 is 1.3kg and 1.5k, respectively.
Comparative Example 1 1 kg of the same silicon was crushed in air to obtain an average particle size of 300 g.
A chlorination reaction was carried out in the same manner as in Example 1 except that chlorosilane was not substantially produced.

Examples 3-5. Reference Example 1° The same test as in Example 1 was conducted except that the particle size of the silicon particles was changed. The results are shown in Table 1.

Table 1 Examples 6-8. Comparative Examples 1-2 The same test as in Example 1 was conducted except that the temperature of the chlorination reaction was changed. The results are shown in Table 2.

Example 9 Example 1 was repeated using trichlorethylene instead of dodecane.

The yields of 5iC14, 5i2C1, and 5i3CI were 569.749,499, respectively.

Example 10 Example 1 was repeated using carbon tetrachloride in place of dodecane.

The yields of 5iC1, Si, C1, Si, and C1° were 589.72g and 46.9g, respectively. ! It was 7.

Claims (1)

[Claims] 1. Chlorosilane (S
A method for producing i_nCl_2_n_+_2 (where n≧3). 2. The inert organic solvent is dodecane, nonane, octane,
The method according to claim 1, wherein the material is at least one substance selected from the group consisting of toluene, carbon tetrachloride, tetrachlorethylene, and trichloroethylene. 3. The method according to claim 1, wherein the silicon particles have an average particle size of 50 μm or more and 2 mm or less. 4. The average particle size of silicon particles is 200 μm or more and 800 μm.
4. The method according to claim 3, which is less than or equal to m. 5. The method according to claim 1, wherein the chlorination reaction temperature is 140°C or higher and 300°C or lower. 6. The method according to claim 5, wherein the chlorination reaction temperature is 160°C or higher and 260°C or lower.