JP4446675B2 - Method for producing alkylsilane or alkylgermane - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
Table In the present invention, useful general formula as CVD film forming material in a semiconductor device manufacturing R _n SiH _4-n or R _n GeH _4-n (wherein, R represents a lower alkyl group of C ₁ ~C _3.) The present invention relates to a method for producing alkyl silane or alkyl germane.
[0002]
[Prior art]
Alkyl silane and alkyl germane are attracting attention as material gases useful as CVD film forming materials in semiconductor device manufacturing.
[0003]
In general, the synthesis method of alkylsilane or alkylgerman is
(1): Reduction of R _n SiX _4-n or R _n GeX _4-n by the action of metal hydrides such as lithium aluminum hydride (LiAlH ₄ ), lithium hydride (LiH), sodium hydride (NaH) Example 2 (CH ₃ ) ₂ GeCl ₂ + LiAlH ₄ → 2 (CH ₃ ) ₂ GeH ₂ + LiCl + AlCl ₃
( ₂ ): Example of a method of alkylating H _n SiX _4-n or H _n GeX _4-n by reacting with dialkylzinc (R ₂ Zn) or Grignard reagent 2SiH ₃ Cl + (CH ₃ ) ₂ Zn → 2CH ₃ SiH ₃ + ZnCl ₂
(3): Example of alkylation by allowing alkyl halide (RX) or olefin to act on SiH ₄ or GeH ₄ SiH ₄ + CH ₃ I → CH ₃ SiH ₃ + HI
Etc.
[0004]
Among these, the production of alkylsilane or alkylgermane is generally performed by using the metal hydride (1) whose raw materials are available at a low cost.
[0005]
For example, a method of synthesizing (CH ₃ ) ₃ SiH by reacting trimethylsilyl chloride ((CH ₃ ) ₃ SiCl) and LiAlH _{4 in} a solvent of dimethoxyethane (DME) is described (Non-patent Document 1). ). Also disclosed is a method for producing a hydride of silicon or germanium by reacting a halogen-containing silicon or germanium compound with LiH in tetrahydrofuran (THF) (Patent Document 1).
[0006]
As in the above example, in the method (1) using a metal hydride, the reaction is generally carried out in an organic solvent. However, in the reaction using an organic solvent, it is necessary to separate the product and the organic solvent, and there is a problem that a trace amount of the organic solvent remains even after purification.
[0007]
As a synthesis method without using a solvent, an organic halogenated silane reduction method using NaH at a reaction temperature of 175 to 350 ° C. is disclosed (Patent Document 2). However, the hydrogenation reaction of organohalogenated silane with NaH is very slow, and there is a problem that a large amount of hydrogen is produced as a by-product when the temperature is raised to increase the reaction rate. NaH easily ignites in the air and is very difficult to handle.
[0008]
[Patent Document 1]
JP-A-2-221110 [Patent Document 2]
US Pat. No. 3,099,672 [Non-Patent Document 1]
J. et al. Amer. Chem. Soc. , 83, 1916 (1961)
[0009]
[Problems to be solved by the invention]
An object of the present invention is to produce a high-purity alkylsilane or alkylgermane with high productivity by using a metal hydride that is safe and has a high yield without leaving an organic solvent or the like.
[0010]
As a result of intensive studies, the present inventors have reacted lithium hydride (LiH) or calcium hydride (CaH ₂ ) with alkylsilyl halide or alkylgermyl halide in the temperature range of more than 100 ° C. and less than 600 ° C. without solvent. As a result, it was found that alkylsilane or alkylgermane can be obtained with good yield, and the present invention has been achieved.
[0011]
That is, the present invention relates to the general formula (1)
R _n MX _4-n (1)
(However, R represents a C ₁ -C ₃ lower alkyl group, X represents a halogen element, M represents Si or Ge, and n represents 1, 2, 3 respectively.)
A compound represented by the formula (alkylsilyl halide or alkylgermyl halide) is reduced in the absence of a solvent to obtain a compound represented by the general formula (2)
R _n MH _4-n (2)
(Where R is a C ₁ -C ₃ lower alkyl group, M is Si or Ge, n is 1, 2
3 respectively. )
In producing a compound represented by the (alkylsilane or alkyl germane), the general formula (1) and a compound represented by lithium hydride or calcium hydride and free at the temperature range below 100 ° C. Ultra 600 ° C. and The present invention provides a method for producing an alkylsilane or an alkylgermane characterized by reacting with a solvent .
[0012]
According to the present invention, since no organic solvent is used, impurities derived from the organic solvent are not mixed. In addition, the selection of the metal hydride to be used is the most important in efficiently carrying out the solvent-free reaction. However, as a result of intensive investigations by the present inventors, LiH and CaH ₂ have excellent hydrogenation in the solvent-free reaction. It was found that it becomes an agent.
[0013]
That is, LiH and CaH ₂ are safe without being easily ignited in the air, and a large amount of by-product hydrogen is generated when reacting with the alkylsilyl halide or alkylgermyl halide as the reactant. In fact, the yield is much higher. In addition, it is relatively stable at high temperatures and has the advantage of not causing runaway reaction due to the property of reversibly absorbing and releasing hydrogen. In NaH and LiAlH ₄ , NaH decomposes irreversibly at 420 ° C. and LiAlH ₄ at 125 ° C. to generate hydrogen. For this reason, when NaH, LiAlH ₄ or the like is reacted without a solvent, a large amount of by-product hydrogen is generated, resulting in a decrease in yield. In addition, runaway reaction due to heat of reaction is likely to occur.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, usable metal hydrides are LiH and CaH ₂ , but the hydrogenation capacity is higher in LiH. When the alkylsilyl halide or alkylgermyl halide, which is a reactive agent, is easily decomposed at a high temperature, it is preferable to use a highly reactive LiH and react at a lower temperature. In terms of productivity and yield, LiH is preferable because of its high reaction rate. The metal hydride may be in the form of a lump or powder, but a powder having a large surface area is preferable because of its high reaction rate.
[0015]
As the alkylsilyl halide or alkylgermyl halide as the reactant, general formula (1) R _n MX _4-n (where R is a lower alkyl group of C _{1 to} C ₃ , X is a halogen element, M is Si, or Ge, n represents 1, 2, and 3, respectively)). Specific examples of the lower alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and the like. For example, methylethylsilyl halide and the like in which these are mixed can be used. As the halogen element, iodine, bromine, chlorine, fluorine and the like can be used, but a chlorinated material which can be obtained at low cost can be preferably used.
[0016]
In the present invention, the reaction temperature is appropriately selected in the range of more than 100 ° C. and less than 600 ° C. according to the kind of the reactant. Below 100 ° C, the activity of the hydrogenating agent is low and the reaction does not proceed. Moreover, when the temperature is 600 ° C. or higher, the yield is reduced because the Si—C bond or Ge—C bond of the reactant is broken, which is not preferable. For example, in the reaction between trimethylsilyl chloride ((CH ₃ ) ₃ SiCl) and CaH ₂ , a reaction temperature of 400 to 500 ° C. is preferable, and in the reaction between dimethylsilyl chloride ((CH ₃ ) ₂ SiCl ₂ ) and LiH. 300 to 400 ° C is preferable. Further, in the reaction of trimethylgermyl chloride ((CH ₃ ) ₃ GeCl) and LiH, 200 to 300 ° C. is preferable.
[0017]
The reaction mode is a reaction between a solid metal hydride and a gas or liquid reactant. In the present invention in which no solvent is used, a solid-gas reaction that can be reacted safely at a high temperature is preferable.
[0018]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this Example.
[0019]
Example 1
0.1 g of LiH was charged into a stainless steel reactor having a diameter of 25 mm × 600 mm. After the reactor was evacuated, the reactor temperature was raised to 500 ° C., and (CH ₃ ) ₃ SiCl was introduced in a gaseous state at 22 KPa. The product after introduction for 5 minutes was collected and analyzed by FT-IR and GC. As a result, trimethylsilane ((CH ₃ ) ₃ SiH) was obtained in a yield of 88%.
[0020]
Example 2
The reaction was conducted in the same manner as in Example 1 except that the reaction temperature was 400 ° C. and 13 KPa of (CH ₃ ) ₂ SiCl ₂ was introduced as a reactant. The product was dimethylsilane ((CH ₃ ) ₂ SiH ₂ ), and the yield was 58%.
[0021]
Example 3
The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 300 ° C. and 4 KPa of (CH ₃ ) ₃ GeCl was introduced as a reactant. The product was trimethylgermane ((CH ₃ ) ₃ GeH) and the yield was 51%.
[0022]
Example 4
The reaction was conducted in the same manner as in Example 1 except that 0.3 g of CaH ₂ was added as a metal hydride and the reaction temperature was 500 ° C. The product was (CH ₃ ) ₃ SiH and the yield was 60%.
[0023]
In any of the reactions of Examples 1 to 4, no hydrogenation reaction occurred at 100 ° C. or lower. Moreover, the impurities mixed into the product were only the raw material, methane and a trace amount of hydrogen, and unnecessary solvent contamination was avoided.
[0024]
Comparative Example 1
The reaction was conducted in the same manner as in Example 1 except that 0.3 g of LiAlH ₄ was added as a metal hydride and the reaction temperature was 120 ° C. As the reaction agent was introduced, the internal pressure of the reactor increased rapidly and the product was analyzed. As a result, (CH ₃ ) ₃ SiH was produced, but 50 vol% of the product was hydrogen.
[0025]
Comparative Example 2
The reaction was conducted in the same manner as in Example 1 except that 0.5 g of NaH was added as a metal hydride and the reaction temperature was 400 ° C. The (CH ₃ ) ₃ SiH concentration in the product after 5 min was 2.5 vol%, and when the reaction temperature was raised to 500 ° C., the internal pressure of the reactor rose rapidly, and the product was analyzed. 30 vol% was hydrogen.
[0026]
【The invention's effect】
According to the present invention, a high-purity alkylsilane or alkylgermane can be safely produced with high productivity without any organic solvent remaining because it is a solventless reaction.

Claims (1)

General formula (1)
R _n MX _4-n (1)
(However, R represents a C ₁ -C ₃ lower alkyl group, X represents a halogen element, M represents Si or Ge, and n represents 1, 2, 3 respectively.)
A compound represented by the formula (alkylsilyl halide or alkylgermyl halide) is reduced in the absence of a solvent to obtain a compound represented by the general formula (2)
R _n MH _4-n (2)
(Wherein, R represents a lower alkyl group of C ₁ ~C _3, M represents each Si, or Ge, n is 1, 2, and 3.)
In producing a compound represented by the (alkylsilane or alkyl germane), the general formula (1) and a compound represented by lithium hydride or calcium hydride and free at the temperature range below 100 ° C. Ultra 600 ° C. and A method for producing an alkylsilane or alkylgerman, characterized by reacting with a solvent .