JPH0328369B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field] The present invention is based on the general formula SixHyOz (where x is a positive integer of 1 or more, y and z are 2x+2 and a positive integer not exceeding 2x, respectively, and one of them is not 0 and x=1) The present invention relates to a method for producing silicon hydride represented by the general formula SilH _2l+2 (l is a positive integer smaller than x) from a silicon compound represented by (z is not 0). [Background Art] With the development of the electronics industry in recent years, the demand for silicon for semiconductors such as polycrystalline silicon or amorphous silicon has increased rapidly. Silicon hydride has recently become more important as a raw material for manufacturing silicon for semiconductors, and demand for silane (SiH ₄ ) and disilane (Si ₂ H ₆ ) in particular is expected to increase significantly in the future as raw materials for semiconductors for solar cells. is expected. Several methods for producing silicon hydride have been known, among which a method for producing silicon hydride by reacting magnesium silicide with an acid has been known for a long time as a particularly easy and economical method. Mg ₂ Si + 4HclinH ₂ OorliqNH ₃ ――――――――――→ 2Mgcl ₂ +1/nSinH _2o+2 + (1-1/n)H _2However , in this method, SiH ₄ and Si ₂ , which have high utility value, In addition to H ₆ , a considerable amount of higher silane is produced, and for example, when water is used as a solvent, the reaction can be carried out at normal temperature and pressure, but about half of the Si in Mg ₂ Si is SipHqOr (p is 3 The above positive integers, q and r, are positive integers not exceeding 2p+2 and 2p, respectively, and one of them is not 0), so it is not economical. In addition, it is known that higher silane is produced as a by-product when silicon hydride is produced by reducing silicon halides. For example, 2Si ₂ cl ₆ + 3LiAlH ₄ inether ――――――――→ 3Licl When Si ₂ H ₆ is produced by the reaction of +Alcl ₃ +2Si ₂ H ₆ , a considerable amount of higher silanes such as Si ₃ H ₈ are produced. On the other hand, it has been reported that high-grade silane SimH _2n+2 (- is a positive integer of 2 or more) can be partially converted into SiH ₄ or Si ₂ H ₆ by thermal decomposition or silent discharge. ₄ , the conversion rate to Si ₂ H ₆ is low and still insufficient. In view of the above points, the present inventors have conducted extensive studies and found that most of the various silicon compounds that are produced as by-products in conventional methods are expressed by the general formula SixHyOz. In particular, it has been found that the desired silicon hydrides such as SiH ₄ and Si ₂ H ₆ can be converted in high yield. [Objective of the Invention] The object of the present invention is to convert various silicon compounds produced as by-products in the conventional methods described above into economically valuable silicon hydrides such as SiH ₄ and Si ₂ H ₆ in high yield. The goal is to provide a method to do so. [Disclosure of the Invention] According to the present invention, the general formula SixHyOz (where x is 1
raw integers greater than or equal to, y and z each 2x+2,
A positive integer not exceeding 2x, one of which is 0
, and when x=1, z is not 0) and an alkyl aluminum hydride, the general formula
A method is provided for producing silicon hydride represented by SilH _2l+2 , where l is a positive integer smaller than x. The present invention will be explained in detail below. The silicon compound used as a raw material in the method of the present invention has the general formula SixHyOz (where x is 1
positive integers greater than or equal to, y and z are each 2x+2,
It is a positive integer not exceeding 2x, one of which is not 0), and preferably contains at least one Si--H bond or Si--Si bond in the molecule. Specifically, for example, disilane (Si ₂ H ₆ ), trisilane (Si ₃ H ₈ ), n-tetrasilane (Si ₄ H ₁₀ ), isotetrasilane (Si ₄ H ₁₀ ),
Cyclohexasilane (Si ₆ H ₁₂ ), polysilene (SiH ₂ -n), disiloxane (Si ₂ H ₆ O), trisiloxane (Si ₃ H ₈ O ₂ ), tetrasiloxane (Si ₄ H ₁₀ O ₃ ), Examples include siloxene ((Si ₂ H ₂ O) n). It is also possible to use a mixture of two or more of these or a mixture thereof. Furthermore, as described below, these can be used dissolved or suspended in diluents such as aliphatic saturated hydrocarbons, aromatic hydrocarbons, and ethers, or organic solvents, and can be used in any of the gas, liquid, and solid phases. It can also be used in Furthermore, the alkyl aluminum hydride used in the method of the present invention has the general formula R ₁ R ₂ AlH or
It is a compound with the reducing ability represented by R ₃ AlH ₂ . Here, R ₁ , R ₂ , and R ₃ all have carbon numbers starting from 1.
up to 10 alkyl groups, e.g. ethyl group,
Examples include n-propyl group, isobutyl group, n-hexyl group, and n-octyl group. R ₁ and R ₂ may be the same or different. Among the compounds represented by the above general formula, preferred examples are dimethylaluminum hydride, diethylaluminum hydride, diisopropylaluminum hydride, diisobutylaluminum hydride, di-2-methylbutylaluminum hydride, and ethylaluminum dihydride. It is also possible to use two or more of these in combination, and it is preferable to use them after diluting them to a desired concentration with an organic solvent as described below. The proportion of these alkylaluminum hydrides to be used is not particularly limited, but is generally in the range of 0.001 to 100 times the molar amount of silicon in the raw material silicon compound. Next, a method of contacting a silicon compound and an alkyl aluminum hydride in the present invention will be described. Basically, it can be carried out in any of the gas phase, liquid phase, and solid phase methods, and as the easiest method to implement, for example, the following method can be adopted. (1) Dissolve a silicon compound and an alkyl aluminum hydride in a solvent and cause a contact reaction in the liquid phase. (2) A gaseous silicon compound is brought into contact with an alkyl aluminum hydride dissolved in a solvent. Of course, the present invention is not limited to these methods. The solvent used here is
Those that have excellent solubility in silicon compounds and do not react with alkyl aluminum hydrides are preferred, such as aliphatic saturated hydrocarbons,
Examples include alicyclic saturated hydrocarbons, aromatic hydrocarbons, and ethers. More specifically, pentane,
heptane, octane, nonane, cyclohexane,
Examples include liquid paraffin, benzene, toluene, xylene, diethyl ether, dibutyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and dioxane. These can be used in combination of two or more kinds, and it is desirable to perform sufficient dehydration. There is no particular restriction on the reaction temperature, but if it is too low, the reaction will be slow, and if it is too high, the alkylaluminum will self-decompose and side reactions will occur, so generally a range of -30°C to 100°C is preferred. A range of 0 to 50°C is used. Also, the reaction time varies depending on the reaction mode, but
The reaction pressure, which is preferably from 1 minute to 48 hours, is sufficient to be normal pressure or 2 kg/cm ² (gauge pressure), but the reaction may be carried out under reduced pressure or increased pressure depending on the reaction temperature or equipment. The raw materials and products used in this reaction are active, and most of them react with oxygen and moisture to decompose or ignite, so the reaction must be carried out in an atmosphere that is inert to the raw materials and products. It must be done. For example, it must be in an atmosphere of inert gas such as helium, argon, nitrogen, or hydrogen that has been sufficiently deoxidized and deignited. This reaction can be carried out in any of the batch, semi-batch and continuous methods. [Preferred Modes for Carrying Out the Invention] The present invention will now be described in more detail with reference to Examples. Example 1 Concentration 20wt% in a separable flask with a capacity of 4
2 and 300 g of diethyl ether were charged. In a hydrogen gas atmosphere, under conditions where the above mixture was refluxing (reaction temperature 35°C), 60 g of magnesium silicide (particle size 100 to 200 mesh,
782mmol-Si) over 200 minutes with stirring, 0.3
Addition continued at a constant rate of g/min. After the reaction is completed (after adding magnesium silicide), the reaction solution is heated to 0°C.
After cooling and standing still, a diethyl ether layer of approximately 0.4
was separated. The temperature of the acidic aqueous solution in the reactor was raised to 80°C, and a small amount of dissolved diethyl ether was expelled and mixed with the diethyl ether layer separated into two layers. During the reaction, the gas generated during the two-layer separation and heating treatment operations of the acidic aqueous solution was initially −70
It was collected in a trap (trap ()) containing diethyl ether cooled to 0.degree. C., and then in a trap (trap ()) cooled at the temperature of liquid nitrogen. Next, the mixture of the diethyl ether layer after the two-layer separation and the ether in the trap () is distilled in a distillation column with about 3 plates to produce Si ₂ H ₄ , Si ₂ H ₆
is distilled to separate SiH ₄ (bp-112℃) and Si ₂ H ₆ (bp-
14.5°C) was added to and collected in a trap () cooled at the temperature of liquid nitrogen. SiH ₄ remaining in the trap () and the diethyl ether layer after distillation,
The amounts of Si ₂ H ₆ , Si ₃ H ₈ , and Si ₄ H ₁₀ were analyzed and quantified by gas chromatography. The amounts of silanes in the trap () and diethyl ether layers were as shown below.

[Table] Furthermore, colorimetric analysis of the amount of Si in the diethyl ether layer revealed that the content was 324 mmol. In addition, the IR spectrum revealed that the silicon compound contained a considerable amount of Si-O-Si bonds in addition to Si-Si bonds and Si-H bonds. Add diethyl ether to this and diethyl ether solution ()
Got 0.5. The Si concentration in this solution () is
0.649mmol Siatm/ml solm, also Si ₃ H ₈ ,
The concentration of Si ₄ H ₁₀ is 0.030 mmol/ml solm, respectively.
It was 0.021 mmol/mlsolm. Next, this ether solution () was dehydrated using 55 g of Molecular Sibu 3A to obtain a diethyl ether solution () with a Si concentration of 0.649 mmol Siatm/ml solm. Si ₃ H ₈ in this solution,
The concentration of Si ₄ H ₁₀ is 0.033 mmol/mlsolm, respectively.
The water content was 0.020 mmol/mlsolm and 2 ppm. A hexane solution of diethylaluminum hydride (concentration 5.9 mmol/
ml), and then 10 ml of diethyl ether solution () containing the above silicon compound was added, and the reaction was carried out at room temperature. The reaction was carried out with stirring, the atmospheric gas was hydrogen, and the gas produced was collected in a trap cooled at the temperature of liquid nitrogen. After 1 hour, the reaction was completed and the collected SiH ₄
The amount of Si ₂ H ₆ was analyzed and quantified by gas chromatography. The amounts of SiH ₄ and Si ₂ H ₆ are 2.09 mmol and 2.09 mmol, respectively.
It was 0.97 mmol, which corresponds to 62.1% of the silicon in diethyl ether used as the reaction solution. Furthermore, the generation ratio of SiH ₄ and Si ₂ H ₆ was (SiH ₄ /Si ₂ H ₆ = 1.08) based on silicon atoms. Examples 2 to 4 In Example 1, the concentration was 5.5 mmol/instead of diethyl aluminum hydride.
The experiment was carried out in the same manner as in Example 1, except that 20 ml of hexane solutions of diisobutyl aluminum hydride, dimethyl aluminum hydride, and ethyl aluminum dihydride of 5.7 mmol/ml, 4.8 mmol/ml, and 4.8 mmol/ml were respectively charged. The results are shown in Table 1. Examples 5 and 6 In Example 1, the reaction between magnesium silicide and hydrochloric acid was carried out using pentane and benzene instead of diethyl ether to obtain the silicon compound solutions shown below.

[Table] In Example 1, an experiment was carried out in the same manner as in Example 1, except that 10 ml of each of the above solutions was used instead of the diethyl ether solution (). The results are shown in Table 1. Examples 7 and 8 In Example 1, Si ₃ H ₈ and SiH ₃ OSiH ₂ OSiH ₃ were used instead of the diethyl ether solution ().
0.221mmol/mlsolm and 0.248mmol/ml respectively
An experiment was conducted in the same manner as in Example 1 except that a diethyl ether solution containing solm was used. The results are shown in Table 1. Example 9 A hexane solution of diethylaluminum hydride (conc.
5.9 mmol/ml), and added Si ₃ H ₈ gas (concentration 5.5 vol%) diluted with hydrogen gas.
Bubbling was carried out at a constant rate of 1 mmol/hr for 6 hours at room temperature. The generated gas was collected in a trap cooled with liquid nitrogen, and after the reaction was completed, the amounts of SiH ₄ and Si ₂ H ₆ were determined by gas chromatography. The results are shown in Table 1.

[Table] (Effects and Industrial Applicability of the Invention) As described above, the present invention uses various methods to reduce the general formula that is produced as a by-product when silicon hydride such as SiH ₄ and Si ₂ H ₆ is produced. By contacting a part of the silicon compound represented by SixHyOz with an alkyl aluminum hydride, it can be converted into useful SiH ₄ , Si ₂ H ₆ , etc. very easily and with high yield, and its industrial applicability must be said to be extremely high. It goes without saying that by applying the method of the present invention to a conventional manufacturing process of silicon hydrides such as SiH ₄ and SixH ₆ , the economic efficiency of the process itself is greatly improved.

Claims (1)

[Claims] 1. A silicon compound represented by the general formula SixHyOz (where x is a positive integer of 1 or more, one of which is not 0, and if x=1, 1 is not 0), and an alkyl By contacting with aluminum hydride, the general formula SilH ₂ l ₊₂ (where l
is a positive integer smaller than x). 2 Silicon compound (SixHyOz) has the general formula
The method according to claim 1, represented by SixH _2x+2 (x is a positive integer of 2 or more). 3 Silicon hydride (SilH ₂ l ₊₂ ) is SiH ₄ or
The method according to claim 1, wherein Si 2 H ₆ is Si ₂ H 6 . 4. The method according to claim 1, wherein the silicon compound is dissolved in an organic solvent.