JPH0829930B2 - Method for producing chloropolysilane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention chlorinates silicon to produce hexachlorodisilane (SiCl ₆ or less and abbreviated as 6CS) and octachlorotrisilane (Si).
Cl ₈ or less and abbreviated as 8CS) and other chloropolysilanes (SinCl
_{2n + 2} , n ≧ 2) The present invention relates to a method for efficiently producing _{2n + 2} , n ≧ 2).

[Prior Art and Problems] Conventionally, chloropolysilane has been produced by heating silicide gas such as calcium silicon, magnesium silicon, or ferrosilicon to feed chlorine gas to chlorinate them.

However, when chloropolysilane is produced by the method of chlorinating the above-mentioned silicide particles, there is a problem that solid by-products such as calcium chloride and magnesium chloride are generated, which block the equipment. A method that does not occur is desired.

Also known is a method of producing chloropolysilane by chlorinating silicon by passing chlorine gas through metal silicon particles. In this reaction, generation of solid by-products is not recognized, but there is a problem that the production rate of chloropolysilane is significantly lower than 1% on the basis of silicon atom as compared with the method using the silicide alloy.

In any case, what is mainly generated in the conventional method is
It is SiCl ₄ , and chloropolysilane (SiCl ₆ SiCl ₈ ) uses only the by-product of SiCl ₄ .

[Means for Solving Problems] The present applicant has attempted to improve a method for producing chloropolysilane by chlorinating silicon particles, and by adding copper or a copper compound as a catalyst to the silicon particles, formation of SiCl ₄ can be achieved. The present invention is a further improvement of the above-mentioned production method, in which a production method in which the yield of chloropolysilane is suppressed is achieved, and which was previously filed (JP-A-63-233007).
In the present invention, the yield of chloropolysilane was further increased by keeping the silicon particle layer in a fluidized state and contacting it with chlorine gas.

[Constitution of the Invention] According to the present invention, a method for producing chloropolysilane by passing chlorine gas through the silicon particle layer at a temperature of 240 to 350 ° C. while keeping the silicon particle layer to which copper or a copper compound is added in a fluidized state is provided. Provided.

The average particle size of the silicon particles used in the method of the present invention is
50 μm or more and 2 mm or less is desirable. If the average particle diameter of the silicon particles is larger than 2 mm, it is difficult to maintain a suitable fluidized state, and if it is smaller than 50 μm, dust is generated during the reaction, which is also not preferable.

It is preferable to use silicon particles having a purity of 97% or more for producing chloropolysilane used for producing silicon for semiconductors.

As copper or a copper compound (copper-based catalyst) added to silicon particles, cuprous chloride CuCl and cupric chloride CuCl ₂ are preferably used. Further, cuprous oxide CuO and cupric oxide CuO may be used. The addition amount of the copper-based catalyst is preferably 0.1 to 20% by weight based on silicon particles in terms of copper. The amount added is 0.1% by weight
If the amount is smaller, the effect of improving the production rate of chloropolysilane is not recognized, while if the addition amount exceeds 20% by weight, the amount of silicon particles is relatively decreased and the production rate of chloropolysilane is lowered.

The above-mentioned points are described in Japanese Patent Application No. 62-65770 (Japanese Patent Laid-Open No. 63-233).
No. 007) common manufacturing method. The present invention is characterized in that the silicon particle layer to which the above copper or copper compound is added is kept in a fluidized state and is brought into contact with chlorine gas at a temperature of 240 to 350 ° C. An ordinary fluidized bed apparatus can be used as the fluidizing means.

A diluent gas is used to fluidize the silicon particle bed pre-filled in the reaction vessel. The diluting gas may be used as a mixture with the chlorine gas as a raw material, or the chlorine gas may be separately supplied after fluidizing the silicon particle layer with the diluting gas. An inert gas such as nitrogen, argon or helium that does not react with chlorine is used as the diluting gas. The production rate of chloropolysilane is not significantly different regardless of which inert gas is used.

The molar ratio of chlorine to the diluted gas is preferably 1/40 to 1. When the molar ratio is less than 1/40, the total amount of silicon chloride is decreased, the ratio of 4CS (SiCl ₄ ) in the total silicon chloride is increased, and the ratio of 6CS and 8CS is decreased, resulting in a large yield. Make a difference.

If the above molar ratio is larger than 1, 8C such as SiCl or SiCl
The production rate of high-molecular-weight silicon chloride having a larger molecular weight than that of S becomes high, and therefore it is not preferable when 6CS and 8CS are selectively produced.

The reaction temperature sensitively affects the yield of 6CS and 8CS. The reaction temperature is preferably 240 to 350 ° C. Below 240 ° C,
The chlorination reaction is difficult to proceed. On the other hand, when the reaction temperature is higher than 350 ° C, only 4CS is produced. Within the range of 240-350 ℃,
A large amount of 8CS is produced on the low temperature side, and a large amount of 6CS is produced on the high temperature side. Therefore, it is possible to limit the yield of 6CS and 8CS by controlling the reaction temperature.

The amount of chloropolysilane produced does not depend on the internal pressure of the reaction vessel. However, if the pressure is lower than atmospheric pressure, the atmosphere may enter the vessel. It is necessary to keep more than that.

[Effects of the Invention] Since the method of the present invention uses a fluidized bed, the gas-solid mixture is vigorous, and almost all the supplied chlorine is wasted in the chlorination reaction. Therefore, the yield of chloropolysilane is extremely high. Moreover, the efficiency of 6CS and 8CS can be effectively controlled by adjusting the reaction temperature.

Incidentally, in the above reaction, copper and silicon are temporarily combined with each other to form an alloy, and this alloyed portion is active so that chlorine is easily combined, and when chlorine gas is contacted, copper is separated and chlorine and silicon are separated. It is believed that they combine to form chloropolysilane. If the silicon particles are a fixed layer,
It is considered that the contact between copper and silicon is insufficient, and thus the production rate of chloropolysilane is low.

In the present invention, since the silicon particles are kept in a fluidized state, the contact between silicon and copper is active and the production rate of chloropolysilane is high.

[Examples and Comparative Examples] The schematics of the apparatus configurations used for carrying out the present invention and comparative examples are shown in the drawings. A heating means 2 is provided on the outer circumference of the reaction vessel 1, and a heating medium is supplied to the heating means 2 from a supply device 3. A storage tank 4 is connected to the top of the reaction container 1, and silicon particles are mixed with copper and a copper compound from the storage tank 4 and supplied to the reaction container 1. A heating supply device 5 for supplying chlorine gas and an inert gas is connected to the bottom of the reaction vessel 1. The silicon particle layer is kept in a fluid state by an inert gas and chlorine gas, and contacts the chlorine gas to generate chloropolysilane. The produced chloropolysilane, unreacted gas, and the like are guided to the outside through the exhaust pipe line 6, collected by the cold traps 7 and 8, and then separated.

Example 0.5 to 20% with respect to metallic silicon using the illustrated apparatus
Approximately 3000 g of 60-200 mesh metal silicon containing the copper-based catalyst described above is charged into a reaction vessel, chlorine and a diluent gas are introduced from the lower portion of the reaction vessel to fluidize the silicon particle layer, and at 240 to 350 ° C. The salification reaction was carried out for about 4 hours.
The exhaust gas from the reaction vessel was cooled and collected, and the condensate was analyzed by gas chromatography. The manufacturing conditions and results are shown in Table 1. The weight ratio of the catalyst to metallic silicon is
It is the ratio of the copper equivalent weight of each copper-based catalyst to the weight of metallic silicon.

Comparative Example Silicon filling method using the same apparatus as in the example The same as the example except that the amount of the copper-based catalyst, the molar ratio of chlorine to the diluting gas, the reaction temperature, the pressure was changed outside the scope of the present invention.
An attempt was made to produce chloropolysilane. The results are shown in Table 2.

[Brief description of drawings]

 FIG. 1 is a schematic diagram of a device configuration used for implementing the present invention. In the figure, 1 ... Reactor container, 2 ... Heating means 3 ... Supply device, 4 ... Storage tank 5 ... Heating supply device, 6 ... Exhaust pipe line 7, 8 ... Trap

Claims (1)

[Claims] 1. A silicon particle layer to which copper or a copper compound is added is kept in a fluid state, and chlorine gas is passed through the silicon particle layer at a temperature of 240 to 350 ° C.
_{2n + 2} where n ≧ 2).