JPH05147920A - Production of partialy substituted fluorosilane - Google Patents

Abstract

PURPOSE:To obtain high-purity partially substd. fluorosilane. CONSTITUTION:Partially substd. fluorosilane expressed by general formula SiHnF4-n ((n) is an integer 1 to 3) is obtd. from partially substd. chlorosilane expressed by general formula SiHnCl4-n ((n) is an integer of 1-3) by a halogen exchanging method. This method features in using zinc fluoride anhydride containing <=0.2wt.% water as a fluorinating agent. Thereby, high-purity partially substd. fluorosilane with little impurity is obtd.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing partially substituted fluorosilanes. More specifically, it relates to an improvement in a method for producing fluorosilane (monofluoromonosilane, difluoromonosilane, trifluoromonosilane) by a halogen exchange method.

[0002]

2. Description of the Related Art Partially substituted fluorosilane is a useful compound for forming a fluorinated amorphous silicon thin film. As a method for producing partially substituted fluorosilanes, a so-called halogen exchange method in which the corresponding chlorosilane is fluorinated with a fluorinating agent is known.

Zinc fluoride (hereinafter referred to as Z
Application using nF ₂ ) (Japanese Patent Laid-Open No. 61-15101)
There is 5). According to the application, since chlorosilane or fluorosilane has a property of being hydrolyzed in the presence of water, it is necessary to completely dehydrate ZnF ₂ used in the reaction as well as the equipment used immediately before use, Z
In the case of nF ₂ , for example, dehydration by heat treatment at 200 ° C. for 4 hours is sufficient.

However, when halogen exchange is performed on partially substituted chlorosilanes using ZnF ₂ treated by this method, the fact that fluorosilanes, silanes, silicon tetrafluoride and the like other than the corresponding partially substituted fluorosilanes are by-produced is found. found.

[0005]

In view of the above problems, the present invention seeks a fluorinating agent that is easy to handle and has good reaction efficiency in producing highly pure partially substituted fluorosilanes by the halogen exchange method. The inventors have found that the object can be achieved by improving the treatment method of ZnF ₂ , and have completed the present invention.

That is, the present invention has the general formula SiH _n Cl
_{When the} partially substituted chlorosilane represented by _4-n (n = 1 to 3) is converted to the corresponding partially substituted fluorosilane by the halogen exchange method, the water content of the fluorinating agent is 0.2% by weight or less. zinc fluoride process for the preparation of partial substitution fluorosilane represented by the general formula _{SiH n F 4-n (n} = 1~3 integer) used.

The present invention will be described in more detail. ZnF ₂ used in the present invention must be an anhydride having a water content of 0.2% by weight or less. ZnF with a water content exceeding 0.2% by weight
Halogen exchange of partially substituted chlorosilanes using ₂ is not preferable because fluorosilanes other than the corresponding partially substituted fluorosilanes, silanes, silicon tetrafluoride and the like are by-produced.

The water content in the present text means a weight percentage including attached water and crystal water. Chlorosilane or fluorosilane has the property of being hydrolyzed in the presence of water, so ZnF ₂ used in the reaction
Must be completely dehydrated. It can be significantly dehydrated by reacting zinc oxide or zinc carbonate with hydrogen fluoride, or by heating commercially available ZnF ₂ tetrahydrate to 150 to 200 ° C. in the production of partially substituted fluorosilanes. Is not enough. Moisture content 0.2
There are several ways to obtain up to wt% anhydrous ZnF ₂ .

For example, after dehydration treatment by the above method, it is preferably 400 to 7 in an inert gas atmosphere or under vacuum.
1-2 at 00 ° C, more preferably 500-600 ° C
A method of performing heat treatment for 0 hours is preferable.

In addition, a zinc compound having no water of crystallization and fluorine
ZnF obtained by reaction of elementary gas _TwoVia the hydrate
It is preferably used because it does not. Zn used for reaction
F_TwoOf course, the equipment to be used should be thoroughly dehydrated just before use.
I need to leave.

The method of contacting chlorosilane and ZnF ₂ is Z
A method of passing chlorosilane in a gaseous state through the nF ₂ packed layer is preferable, but the present invention is not limited thereto.

The reaction between chlorosilane and ZnF ₂ is a considerably exothermic reaction, and since the partially substituted fluorosilane produced is thermally unstable, it is necessary to effectively remove the produced heat in order to obtain high purity. In that respect, a method of suspending ZnF ₂ in an organic solvent such as ether to carry out the reaction is effective.

The reaction temperature is preferably -30 to 40 ° C, more preferably -10 to 5 ° C. If the reaction temperature is less than -30 ° C, the reaction rate of the halogen exchange reaction decreases,
On the contrary, if the reaction temperature exceeds 40 ° C., the partially substituted fluorosilane produced is thermally decomposed, and the reaction yield is reduced, which is not preferable.

[0014]

The present invention will be described in more detail with reference to the following examples. In addition,% means% by weight.

Example 1 ZnF ₂ .4H ₂ O was dehydrated at 200 ° C. for 4 hours, and further heat-treated under vacuum at 600 ° C. for 2 hours. After the treatment, it was put in a polyethylene bag and stored in a desiccator. This Zn
Before using F ₂ , the weight change from room temperature to 700 ° C. was measured by a differential thermal balance with a He gas purge. As a result,
The weight loss was 0.14%. This ZnF ₂ 200
g into a 200 ml glass flask and set the inside of the system to N
Replaced well with ₂ . After that, SiHCl ₃ was fed into the flask at a rate of 0.5 g / min so that the total amount became 100 g under N ₂ flow. During the reaction, the flask was immersed in ice water to prevent the reaction temperature from rising.

The gas generated from the flask was collected in a liquid nitrogen trap after removing impurities with a dry ice acetone trap. The yield based on SiHCl ₃ was 77%. The purity of the collected gas (SiHF ₃ )
Is 98%, and the impure gas components of the same group are each 0.
It was 5% or less.

Example 2 ZnF ₂ .4H ₂ O was dehydrated at 200 ° C. for 4 hours and further N
ZnF ₂ heat-treated at 600 ° C. for 2 hours in _two atmospheres was stored in the same manner as in Example 1, and the weight loss before use was measured according to Example 1 and found to be 0.17%. This Z
200 g of nF ₂ was placed in a 1-liter glass flask equipped with a stirrer and suspended in 400 ml of anisole.

After thoroughly replacing the inside of the system with N ₂ , 100 g of SiH ₃ Cl was fed into the flask at a rate of 0.5 g / min while stirring. During the reaction, the flask was immersed in ice water to prevent the reaction temperature from rising, and a reflux condenser was attached to prevent evaporation of anisole.

The reaction gas generated from the flask was collected in a liquid nitrogen trap after removing impurities with a dry ice acetone trap. The yield in SiH ₃ Cl base was 85%. The purity of the collected gas (SiH
₃ F) was 98%, and the congenital impure gas components were 0.5% or less, respectively, as shown in Table 1.

Example 3 ZnF ₂ obtained by the reaction of ZnO and F ₂ gas was stored in the same manner as in Example 1, and the weight loss before use was measured according to Example 1 to be 0.18%. .. This Zn
It was produced SiH ₂ F ₂ from the SiH ₂ Cl ₂ at F ₂ 200 g Example 2 The same manner. The yield in SiH ₂ Cl ₂ base was 85%. The collected gas (SiH
_{The 2} F ₂ ) purity was 98%, and the impure homologous gas components were 0.5% or less for each as shown in Table 1.

Comparative Example 1 ZnF₂・ 4H₂Zn dehydrated from O at 200 ° C. for 4 hours
F₂Was stored in the same manner as in Example 1, and the weight loss before use was measured.
When determined, it was 1.84%. This ZnF ₂use
The reaction was performed in the same manner as in Example 1 except that the above was carried out. result
As shown in Table 1, SiHF₃ Congenital impurities other than implemented
It was found that more by-product was produced and the yield was lower than in Example 1.
It was

Comparative Example 2 The reaction was performed in the same manner as in Example 2 except that the same ZnF ₂ as in Comparative Example 1 was used. The results are as shown in Table 1, SiH
It was found that a large amount of homologous impurities other than ₃ F were by-produced as compared with the examples, and the yield was low.

Comparative Example 3 The reaction was performed in the same manner as in Example 3 except that the same ZnF ₂ as in Comparative Example 1 was used. The results are as shown in Table 1, SiH
It was found that a large amount of homologous impurities other than ₂ F ₂ were by-produced as compared with the examples, and the yield was low.

[0024]

[Table 1]

[0025]

INDUSTRIAL APPLICABILITY As described in detail above, the present invention, as shown in the examples and comparative examples, is a method for producing a partially substituted fluorosilane according to the present invention. By using zinc fluoride, it is possible to produce a partially substituted fluorosilane with significantly higher yield and less homologous impurities, compared with zinc fluoride that has been generally used from the past, and the effect is There is an extremely large one.

That is, in the comparative examples which are out of the scope of the present invention, the generation of the homologous impurities is high and therefore the yield is low. On the other hand, it is clear that the Examples within the scope of the present invention are all excellent in these performances, and the present invention is of great significance.

Claims (1)

[Claims] 1. The general formula SiH _n Cl _4-n (n = 1 to 3)
In the conversion of the partially substituted chlorosilane represented by the formula (1) to the corresponding partially substituted fluorosilane by the halogen exchange method, the water content as a fluorinating agent is 0.2% by weight.
A method for producing a partially substituted fluorosilane represented by the general formula SiH _n F _4-n (n = an integer of 1 to 3), characterized by using the following anhydrous zinc fluoride.