JPS6389414A - Production of chloropolysilane - Google Patents

Abstract

PURPOSE:To obtain chloropolysilane with high reaction efficiency without producing solid by-product and dust by chlorinating silicon particles in a specified inert liq. CONSTITUTION:The chloropolysilane (SinCl2n+2, wherein n>=2) is obtained by chlorinating this silicon particles having >=2mm mean particle size in the liq. which is inert to silicon and chlorine or to hydrogen chloride and chlorosilane. As the above-mentioned inert liq., the molten salt of zinc chloride and potassium chloride, the molten salt of zinc chloride and sodium chloride, the molten salt of zinc chloride, sodium chloride and potassium chloride, and then an organic fluoric compd. (e.g. perfluoropolyether oil), etc., are exemplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing chloropolysilane 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 chloropolysilane has recently become particularly important as a raw material for manufacturing such semiconductor silicon. There is.

Of course, chloropolysilane can be thermally decomposed as it is to grow epitaxial silicon on a semiconductor silicon wafer, and can also be used as a silica source for optical communications with a high germanium doping rate.

In addition, chloropolysilane is further reduced to polysilane represented by the following formula (I), and 5lnHzn+z (n≧2) (I
) This is thermally decomposed and used as a raw material for silicon epitaxial semiconductors and amorphous silicon.

For example, when disilane Si, H, is used to form an amorphous silicon film by thermal decomposition or glow discharge decomposition, the deposition rate of the film formed on the substrate is much higher than that of monosilane SiH. 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 by heating an alloy of metal and silicon, such as calcium silicon, magnesium silicon, or ferrosilicon, or by a chlorination reaction by feeding chlorine gas into the silicon particles.

[Problem that the invention seeks to solve]

When producing chloropolysilane using the conventional method, solid by-products such as calcium chloride and magnesium chloride and unreacted silicon or silicide fine particles turn into dust and produce a product (
Chloropolysilane (chloropolysilane) can be mixed into condensate or cause blockage of pipes, etc. As a commercial production method, there is a need for a method for producing chloropolysilane that does not generate dust and has a high reaction efficiency between silicon and chlorine.

[Points of focus and knowledge related to solving the problem] The present inventor has investigated the possibility of providing a method for producing chloropolysilane that does not generate solid by-products or dust due to the reaction between silicon and chlorine or hydrogen chloride. The present invention was achieved by discovering a method for carrying out the chemical reaction in a liquid that is inert to chlorine, silicon, and chlorosilane.

[Means to solve the problem]

That is, according to the present invention, chloropolysilane (SinCQ) is produced by chlorinating silicon particles in a liquid inert to chlorine or hydrogen chloride, silicon, and chlorosilane.
Provided is a method for manufacturing zn(n≧2).

This method produces virtually no solid by-products;
Further, since unreacted silicon is subjected to chlorination while being captured in a liquid that is inert to chlorine, hydrogen chloride, and chlorosilane, no dust is generated.

In the present invention, the liquid inert to chlorine, hydrogen chloride, silicon, and chlorosilane is not particularly limited, but includes, for example, a molten salt of zinc chloride and potassium chloride, a molten salt of zinc chloride and sodium chloride, and a molten salt of zinc chloride and sodium chloride. and organic fluorine compounds such as molten salt of potassium chloride, perfluoropolyether oil, perfluorotri-lower alkylamine, and the like.

The higher the purity of the silicon particles used in the method of the present invention, the lower the amount of solid by-products produced, and the purity is determined by taking this into account, but is 97% or higher. is desirable. In the present invention, the silicon particles preferably have an average particle diameter of 2rrn or less, and the chlorination is carried out at a temperature of 140°C or higher and 3rrn.
It is desirable to carry out the test at a temperature below 00°C.

If the average particle size of the silicon particles is larger than 2 mm, the contact efficiency with chlorine is poor and it is not suitable for practical use. Further, if the chlorination temperature is lower than 140°C, the reaction rate is too slow, which is unsuitable, and if it exceeds 300°C, the production rate of chloropolysilane decreases, which is also unsuitable. In addition, 5iCQ4 is produced as a by-product with the production of chloropolysilane, but 5i2 is produced by distillation.
Cf1. , Si, CQ, etc. can be easily isolated.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the following Examples do not limit the scope of the present invention.

〔Example〕

Example 1 Silicon Log with a purity of 97.5% and an average particle size of 1 μm,
A glass reaction vessel was filled with 100 g of mixed powder having a composition of 60 mol% zinc chloride, 20 mol% sodium chloride, and 20 mol% potassium chloride. After heating and melting at 203° C. while flowing nitrogen gas to disperse silicon well in the molten salt, chlorine gas was introduced at a rate of 50 mR/min and reacted for 4 hours. When the product chloropolysilane and the by-product 5iCI24 were collected as a condensate, 5i(jl,, Si, CF!,) was obtained.

The amounts of Si and CQ are 12gt and 17gt, respectively.
It was 1g.

No dust generation was observed during this reaction.

Examples 2 to 5 The same tests as in Example 1 were conducted except that the type of liquid inert to chlorine and the chlorination reaction temperature were changed. The results are in Table 1
It is as follows.

Table 1 Example 2 ZnC454%, K (446%
228 41.53K (:ff29%, ZnC
Q, 71% 262 40.64 NaC140,
5%, ZnCf1.59.5%262 44.1 Examples 6 to 8, Comparative Example 1 The same test as in Example 1 was conducted except that the silicon particle size was changed. The results are shown in Table 2.

Table 2 Example 6 10 39.57
100 43.1 8 2000 37.2 Comparative Example 1 2500 8.0 Examples 9 to 1, Comparative Examples 2 to 3 The chlorination reaction was carried out in the same manner as in Example 1 except that the temperature of the chlorination reaction was changed. Ta. The results are shown in Table 3.

Table 3 Example 9, 140 39.210
220 46.3 11 300 44.7 Comparative example 2 100 No reaction 3
350 0.5 Example 12 A chlorination reaction similar to that in Example 1 was carried out, and the resulting gas was distilled to isolate Si, Cl2G, Si, (jl).

The yields were 16g and 9g, respectively6 and their purity by gas chromatography was 99.999.
% or more.

Example 13 20 g of silicon with an average particle size of 0.3 μm was mixed with 20 g of potassium chloride.
7.6 g of sodium chloride, 21.4 g of sodium chloride, and 151 g of zinc chloride, and after replacing the gas with nitrogen gas in a flask, heated to 240°C and melted, hydrogen chloride gas was introduced into the molten salt at a flow rate of 50 mQ/ It blew for 5 hours in minutes. The produced gas was cooled and liquefied, and its composition was analyzed by gas chromatography. The results are shown in Table 4. still,
During gas blowing, virtually no dust was generated.

Table 4 SiCQ4Si2CQGSi, CD,.

Claims (1)

[Claims] 1. Chlorination reaction of silicon at a temperature of 140°C to 300°C in a liquid inert to silicon and chlorine or hydrogen chloride and chlorosilane using silicon particles with an average particle size of 2 m or less Chloropolysilane (
A method for producing Si_nCl_2_n_+_2 (where n≧2). 2. The method according to claim 1, wherein the liquid inert to silicon, chlorine, and chlorosilane is a molten salt of zinc chloride and potassium chloride, a molten salt of zinc chloride and sodium chloride, or The method is one of molten salts of zinc chloride, sodium chloride and potassium chloride. 3. The method according to claim 1, wherein the liquid inert to silicon and chlorine or hydrogen chloride and chlorosilane is an organic fluorine compound. 4. The method according to claim 3, wherein the organic fluorine compound is perfluoropolyether oil.