JPS61151016A - Production of fluorosilane - Google Patents

Abstract

PURPOSE:To obtain a high-purity fluorosilane in improved reaction yield, by suspending a fluorinating agent in anisole, and reacting a chlorosilane with the suspension. CONSTITUTION:An anhydrous fluorinating agent such as SbF3, AsF3, TiF4, ZrF2, etc. which is heat-treated at about 200 deg.C for about 4hr and completely dehydrated is suspended in anisole to give slurry having 5-50wt% concentration of the fluorinating agent, the system is sufficiently replaced with N2, the temperature is controlled to -30-70 deg.C, a chlorosilane in a gaseous state, corresponding to an obtained fluorosilane, is passed through the slurry and halogen exchange reaction is carried out, to give a fluorosilane shown by the formula (n>=1, 0<=m<=2n+1).

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing fluorosilane.

More specifically, the present invention relates to an improvement in a method for producing fluorosilane using a halogen exchange method.

(Prior Art and its Problems) Fluorosilane is a compound used when forming a fluorinated amorphous silicon thin film.

And the fluorosilane mentioned here is S i 2 F
It includes not only full fluorides such as a but also partial fluorides such as 81□H2F.

As a method for producing fluorosilane, a corresponding chlorosilane is fluorinated with a fluorinating agent. A so-called halogen exchange method is known.

Fluorinating agents used at that time include SbF3, As
F! , T i F4, Sn F4, ZnF2, etc. Common methods for reacting these solid fluorides with gaseous or liquid chlorosilane include passing chlorosilane in gaseous form through a fluoride packed bed, or dropping liquid chlorosilane dropwise into a fluoride layer. be.

However, these methods have the disadvantage that the reaction yield is not satisfactorily high and that side reaction products are quite likely to be produced.

Also known is a method in which ether, pentane, etc. are used as a solvent, and a fluoride is suspended in these solvents and reacted with chlorosilane.

However, although this method improves the reaction yield considerably, there still remains some intermediates in which chlorine could not be completely replaced by fluorine, and these are difficult to separate even by operations such as distillation. Many have the major problem of reducing the purity of the product. Furthermore, since the vapor pressure of the reaction solvent is quite high, there is also the problem that the reaction solvent mixes into the product.

(Means for Solving the Problems) In view of the above-mentioned problems, the present inventors have conducted intensive studies on a method for obtaining fluorosilane with a high reaction yield and high purity. It was discovered that the object could be achieved by making it cloudy and reacting it with chlorosilane, leading to the completion of the present invention.

That is, the present invention has the general formula S In H2mF2n+2-
m (n is an integer where n2>1 and 1m is an integer where 0≦m and ≦2n+1) is produced from the corresponding chlorosilane by a halogen exchange method with a fluorinating agent. This method for producing fluorosilane is characterized by carrying out the reaction by suspending the agent in anisole.

As the fluorinating agent used in the present invention, conventionally known Sb
F3. AsF3. TiF4.5nF4. It can be applied to all materials such as ZnF2. Chlorosilane or fluorosilane is a reaction raw material used in one reaction because it has the property of being easily hydrolyzed in the presence of water.

It is necessary to sufficiently remove water from the fluorinating agent, solvent, and equipment.For example, the fluorinating agent must be completely dehydrated by heat treatment at 200°C for 4 hours immediately before use.

The effect of using anisole as a solvent in the present invention is that, although the details are not clear, it dissolves the metal chloride produced by the reaction, constantly renewing the fluorinated surface and keeping it active, and reducing the heat generated by the reaction. Distribute 1
It is thought that the purpose is to prevent an increase in the reaction rate, but from this point of view, it is preferable for the slurry concentration of the fluorinating agent suspended in anisole to be as low as 5% by weight (hereinafter simply referred to as %). ) degree, high (but 50%
It is.

The reaction temperature is determined by taking into account the reactivity of rogane exchange or the thermal stability of the fluorosilane produced, but -
The temperature is 30°C to 70°C, preferably -10°C to 40°C.

If the reaction temperature is too high, side reaction products are likely to be produced, thus reducing the purity of the product, and conversely, if the reaction temperature is too low, the reaction rate of the halogen exchange reaction will decrease.

(Examples and Comparative Examples) The present invention will be explained in more detail below using Examples and Comparative Examples.

Example 1 Zinc fluoride 7200f dehydrated at 200°C for 4 hours
II! glass flask with stirrer, 400
rnl was suspended in anisole.

After sufficiently replacing the inside of the system with N2, 5i was added while stirring.
10 of HC1!3 was fed into the flask at a speed of 0.5 f/min. During the reaction, the flask was immersed in ice water to maintain a constant reaction temperature, and a reflux condenser was installed to prevent evaporation of anisole.

The reaction gas generated from the flask was collected in a liquid nitrogen trap after removing impurities using a dry ice acetone lamp. The amount recovered was 53y (yield: 84%), and this was identified as SiHF3 from the IR absorption characteristics. Furthermore, when the produced gas was absorbed into an HF aqueous solution and the chlorine concentration in the produced gas was measured, it was only 70 ppm, indicating that the purity of the product was extremely high.

When the reaction was carried out in the same manner as in Example 1, the yield of SiHF3 was 70%.

Example 3 5IH2CI! in the same manner as Example 1! When 2 was fluorinated, SiH2F2 was obtained with a yield of 87%.

The chlorine concentration in the product gas was only 50 pI)m.

Comparative Example 1 When a reaction was carried out in the same manner as in Example 1 using anhydrous ether as a suspending solvent, the yield was only 53%, and the chlorine concentration in the produced gas was as high as 1.73%.

Comparative Example 2 When a reaction was carried out by mixing zinc fluoride and 5IHC1!3 without using a suspending solvent, the yield was 42% and the chlorine concentration in the produced gas was as high as 2.73%. Ta.

Claims (1)

[Claims] (1) A method for producing fluorosilane, which comprises bringing a fluorinating agent suspended in anisole into contact with chlorosilane.