JPH078722B2 - Method for producing silicon hydride - Google Patents

Description

TECHNICAL FIELD The present invention relates to a silicon hydride represented by the general formula Si _n H _{2n + 2} (n is a positive integer of 1 or more) by reacting an alloy containing silicon with an acid. To a method of manufacturing.

BACKGROUND ART With the recent development of the electronics industry, demand for semiconductor silicon such as polycrystalline silicon or amorphous silicon is rapidly increasing. Silicon hydride Si _n H _{2n + 2} has recently become more important as a raw material for the production of such semiconductor silicon, especially silane (SiH ₄ ) and disilane (Si
₂ H ₆ ) is a raw material for semiconductors for solar cells, and it is expected that demand will increase significantly in the future.

Conventionally, as a method for producing silicon hydride, several methods are known as exemplified below.

Among them, the method of reacting a silicon alloy according to the present invention, particularly magnesium silicide with an acid, has long been known as the easiest method.
That is, the methods (1) and (2) are advantageous over other methods in that an expensive reducing agent is not required (compared to), and a reaction can be performed at around room temperature and pressure (compared to). In particular, when disilane (Si ₂ H ₆ ) is produced, it can also be obtained by reducing expensive hexachlorodisilane (Si ₂ Cl ₆ ) with a metal hydride by, for example, the method described below. Very easily with disilane (Si ₂ H ₆ )
Can be obtained.

However, in the method (1), a side reaction of a silicon compound having a siloxane bond cannot be avoided by a side reaction, and the conversion rate of silicon to silicon hydride in the silicon alloy (hereinafter referred to as yield) is low, and SiH ₄ and Si It had the drawback that the production rate of ₂ H ₆ remained unchanged. (The total yield of SiH ₄ and Si ₂ H ₆ is about 30%, (SiH ₄ / Si ₂ H ₆ ) molar ratio ~ 2 (Si atom base)) For example, Journal of the Chemical Society ), 1131 (1
946)) Further, as the reaction progresses, viscous black solids accumulate in the reactor, so that they adhere to the wall of the reactor, which lowers heat transfer and results in poor stirring. There was also. The present inventors have made diligent efforts to solve this problem, first, an organic solvent such as an ether compound or a hydrocarbon is allowed to coexist in the reaction system, and a by-product higher silane soluble in the organic solvent is produced. by methods such as by lower into SiH _4, Si ₂ H _6, the total yield of SiH _4, Si ₂ yield of H ₆ was proposed to improve by a large margin (SiH ₄ and Si ₂ H ₆ 60 To 70%, for example, Japanese Patent Application Nos. 58-245772, 58-245773, 59-11938059-034830, 59
-110703, 59-109358, 59-110704, 59-113194, 59-10646
1, 59-175663, 59-175662).

However, even according to the invention, it is difficult to arbitrarily change the production ratio of SiH ₄ and Si ₂ H ₆ , and it is almost (SiH ₄ / Si ₂ H ₆ )
The value of the molar ratio was within a narrow range of 1 to 2 (Si atom base).

In one method, although the yield of SiH ₄ was high (70
, 80%), and the low yield of Si ₂ H ₆ (usually 5%)
Less than). Of course, it is difficult to arbitrarily change the generation ratio of both.

The present inventors diligently studied the improvement of Si ₂ H ₆ yield, which is a problem in the reaction between these silicon alloys and acids, and a method of arbitrarily controlling the production ratio of SiH ₄ and Si ₂ H ₆ , The present invention has been completed.

That is, the present invention is characterized in that in the method for producing SiH ₄ and Si ₂ H ₆ by causing an alloy of silicon and magnesium and an acid to act, the alloy contains a third component element. According to the present invention, Si ₂ H ₆
It is possible to significantly improve the yield, and SiH ₄ and Si
The production rate of ₂ H ₆ can be controlled arbitrarily.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing a silicon hydride represented by the general formula Si _n H _{2n + 2} (n is a positive integer) by reacting an alloy of silicon and magnesium with an acid. In the alloy, in the periodic table except for oxygen, nitrogen and silicon, IIIB,
Addition rate of element of IVB, VB or VIB subgroup to silicon in alloy (100 x g of added element / g of silicon)
The number of atoms is 0.5% to 20%.

In the present invention, the reaction between the silicon alloy and the acid is carried out by water or ammonia, hydrazine, ethylamine, hexylamine, ethylenediamine, piperidine, aniline, nitrogen-containing organic compounds such as pyridine, or diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane. It can be carried out in a solvent such as an ether compound such as anisole or a mixed solvent thereof, and among these, water, ammonia and hydrazine are particularly preferable.

As the acid, any acid may be used as long as it acts as an acid in the above solvent with the silicon alloy, and various inorganic acids or organic acids can be used. For example, when water is used as the solvent, hydrochloric acid, hydrobromic acid, hydrofluoric acid,
Sulfuric acid, phosphoric acid, acetic acid, formic acid, oxalic acid, etc., when using ammonia as a solvent, compounds such as ammonium chloride, ammonium bromide, ammonium rhodate, and when using hydrazine as a solvent, hydrazyl chloride, etc. Is used as the acid.

Further, as described in the background art section, in the water solvent system, it is preferable in the yield of silane to coexist with an organic compound such as an ether compound, a hydrocarbon and a halogenated hydrocarbon as we have proposed. .

The alloy composed of silicon and magnesium in the present invention has a chemical composition close to that of Mg ₂ Si, and usually contains a predetermined amount of silicon and magnesium in an inert gas atmosphere such as hydrogen or argon or helium at 450 ° C. or higher. It is obtained by firing at.

The present invention is characterized by including a specific third component element in this alloy. That is, the third component used in the present invention is oxygen in the periodic table (described in New Experimental Chemistry Lecture, published by Maruzen Co., Ltd. (1977)),
IIIB, IVB, VB or V excluding nitrogen and silicon
An element of the IB subgroup, specifically, Tl, In, Ga, Al,
B, Pb, Sn, Ge, C, Bi, Sb, As, P, Po, Te, Se and S. Various methods can be used for adding these third component elements, but the method of forming an alloy containing silicon, magnesium and the third component element is most preferable. Specifically, for example, a mixture of silicon, magnesium and a third component element is fired in hydrogen or an inert gas, or magnesium silicide and the third component element are composed of silicon and a third component. An alloy (or compound) (of course, a specific third component defined in the present invention may be contained as an impurity from the beginning in the raw material silicon) may be used, magnesium, and an alloy composed of magnesium and the third component. It is obtained by firing (compound) and silicon respectively. These alloys can be obtained not only from the simple substance of each component, but also from a compound with another element as a starting material. For example, a method of using each oxide as a starting material and simultaneously performing a deoxidation reaction and an alloy production reaction in a reducing gas atmosphere can be adopted. The production temperature of the third component-containing alloy in the present invention is in the range of 450 to 1200 ° C, preferably 500 to 1000 ° C.
In addition to this, it is possible to use the third component element physically mixed with magnesium silicide at room temperature,
In this case, the effect of the invention is small. The addition amount of the third component element is indicated with respect to silicon in the silicon alloy.

That is, (g-atms of additive element / g-atms of silicon) x 100
Is defined as the addition rate, the addition rate is 0.5% to 20%, preferably 1% to 10%.

If the addition rate is lower than this, the effect of the added element is small, and even if the addition rate is higher than this, SiH ₄ and Si ₂ H ₆
The effect of changing the ratio of is not obtained.

Further, the additive component may be two or more kinds, and may contain a third component element outside the scope of the present invention in addition to silicon and magnesium.

The reaction mode between the silicon alloy and the acid is not particularly limited, and various commonly used methods can be adopted. For example, a silicon alloy is charged in an acidic aqueous solution. Examples of the method include charging a silicon alloy into an ammonia solution in which ammonium chloride is dissolved. Although it is economically desirable to use the silicon alloy and the acid in the reaction molar equivalents, it is actually preferable that the amount of the acid used is excessive in view of the yield of silicon hydride. For example, ((H ⁺ / Mg ₂ Si) molar ratio = 4.0) or more, preferably ((H ⁺ / Mg ₂ Si) molar ratio = 4.4 or more).

The reaction temperature, reaction time, solvent used, and other detailed reaction conditions can be directly carried out according to the method already disclosed in the above-mentioned application by us, or known per se.

The present invention relates to a method for producing silicon hydride by the reaction of an alloy consisting of silicon and magnesium with an acid, and the present invention relates to another metal hydride which can be produced by the reaction of an alloy with magnesium and an acid, specifically Can be easily applied to the production of germanium hydride, phosphorus hydride, antimony hydride, lead hydride and the like.

EXAMPLES Hereinafter, the present invention will be described more specifically by way of examples.

<Example 1> Silicon powder (manufactured by Mitsuwa Chemical Co., Ltd., purity 99.9% or more, particle size 20)
4.21 g of magnesium powder (manufactured by Wako Pure Chemical Industries, purity 99.9% or more) 7.29 g, and lead powder (manufactured by Wako Pure Chemical Industries, special grade, particle size of 200 mesh or less) 0.62 g (2 mol% of Si)
) At a temperature of 650 ° C. in a mixed gas of argon and hydrogen (hydrogen content 3 vol.%).
(The alloy was crushed in a mortar to obtain 80 mesh or less after firing).

A tubular separable flask having a capacity of 300 ml was charged with 200 ml of a hydrochloric acid aqueous solution having a concentration of 20 wt%. 6.32 g of the above silicon alloy (78.2 mmo as Si) in this hydrochloric acid aqueous solution in a hydrogen gas atmosphere.
l) was added continuously with stirring at a constant rate of about 0.16 g / min for 40 minutes. The temperature during the reaction was set to 0 ° C., and after the addition of the silicon alloy was completed, the reaction solution was raised to room temperature, and the reaction mixture was heated in a hydrogen stream.
Hold it as it is for 60 minutes, and keep SiH ₄ and Si ₂ H in the reactor.
Completely eliminated ₆ . The produced gas is collected in a trap cooled at the liquid nitrogen temperature, and after the end of the experiment, the Si in the collected gas is collected.
The amounts of H ₄ and Si ₂ H ₆ were analyzed and quantified by gas chromatography.

The amounts of SiH ₄ and Si ₂ H ₆ were 6.6 mmol and 11.4 mmol, respectively. The amounts of SiH ₄ and Si ₂ H ₆ correspond to 37.6% of silicon in the magnesium silicide subjected to the reaction, and (SiH ₄ / Si ₂ H 6
₆ ) The molar ratio was 0.29 (silicon atom base).

<Examples 2 to 7> In Example 1, 0.36 g of tin powder (manufactured by Wako Pure Chemical Industries, Ltd., 200 mesh or less) instead of lead powder, 0.22 g of germanium powder (manufactured by Wako Pure Chemical Industries, purity 99.99%), aluminum Powder (manufactured by Junsei Chemical Co., Ltd., particle size 250 mesh) 0.081g, Bismuth powder (manufactured by Soegawa Rikagaku Co., purity 99.99%, particle size 200 mesh or less) 0.63g, Selenium powder (manufactured by Wako Pure Chemical Industries Ltd.) 0.24g, activated carbon (Junsei Kagaku) An experiment was conducted in the same manner as in Example 1 except that a silicon alloy was produced using 0.036 g (manufactured by the company). However, when activated carbon was added, the alloy production temperature was 950 ° C.

The results are shown in Table 1.

<Comparative Examples 1 and 2> An experiment was performed in the same manner as in Example 1 except that silicon and magnesium were fired at 650 ° C and 950 ° C, respectively, without adding lead.

The results are shown in Table 1.

Examples 8 to 14 A tubular separable flask having a capacity of 300 ml was charged with 200 ml of a 20 wt% concentration hydrochloric acid aqueous solution and 40 ml of diethyl ether. In a hydrogen gas atmosphere, the same silicon alloy as that used in Examples 1 to 7 was added to this mixed solution in the same amount (7% as Si).
(8.2 mmol) was added at a constant rate over 40 minutes. An experiment was performed in the same manner as in Example 1 except that the reaction was performed under reflux of diethyl ether (35 ° C).

The results are shown in Table 1.

<Examples 15 and 16> Same as Example 8 except that a mixture of 4.21 g of silicon, 7.29 g of magnesium and 3.1 g and 0.2 g of lead, respectively, was fired at 650 ° C. for 4 hours as the silicon alloy. The experiment was conducted.

The results are shown in Table 1.

<Examples 17, 18, and 19> Example 8 except that the mixture containing lead, tin, and aluminum was baked at 950 ° C. for 4 hours and used as a silicon alloy in Examples 8, 9, and 11. , 9 and 11 were conducted.

The results are shown in Table 1.

<Example 20> As a silicon alloy, 4.21 g of silicon, 7.29 g of magnesium,
6 mixture of 0.62 g lead and 0.081 g aluminum
An experiment was conducted in the same manner as in Example 8 except that the one that was baked at 50 ° C. for 4 hours was used.

The results are shown in Table 1.

<Example 21> Magnesium silicide (Mg ₂ Si) 1 previously manufactured at 650 ° C
The mixture of 1.5 g and 0.62 g of lead was further calcined at 650 ° C. for 4 hours. An experiment was conducted in the same manner as in Example 8 except that this silicon alloy was used in the reaction.

The results are shown in Table 1.

<Examples 22 and 23> Alloy composed of magnesium and germanium (chemical composition Mg
₂ Ge) 0.37 g, silicon 4.21 g, and magnesium 7.14 g, which were calcined at 650 ° C. for 4 hours, and an alloy of silicon and aluminum (chemical composition Si 0.95
Al 0.05) 1.68g, silicon 2.61g and magnesium 7.29g
An experiment was performed in the same manner as in Example 8 except that the product obtained by firing at 650 ° C. for 4 hours was used.

The results are shown in Table 1.

<Comparative Examples 3 and 4> An experiment was performed in the same manner as in Example 8 except that silicon and magnesium obtained by firing at 650 ° C. or 950 ° C. for 4 hours in Example 8 were used as the silicon alloy.

<Examples 24 to 30> In a tubular separable flask having a capacity of 300 ml, 9.7 g of ammonium chloride powder and the same silicon alloy as those used in Examples 1, 2, 4, 5, 6, 17 and 19 were each given a predetermined amount (Si. (37.0 mmol) was thoroughly stirred and mixed. A reflux condenser cooled at dry ice temperature was attached to the reactor, and ammonia was supplied at a constant rate of 1.0 g / min for 30 minutes in a hydrogen atmosphere to carry out the reaction while refluxing the ammonia (-33 ° C). After the supply of ammonia was completed, the state was maintained for another 30 minutes. The produced silane gas was separated from the accompanying ammonia by washing with hydrochloric acid, and then collected in a trap cooled at liquid nitrogen temperature. After the experiment, SiH ₄ in the collected gas,
The amount of Si ₂ H ₆ was analyzed and quantified by gas chromatography.

The results are shown in Table 1.

<Comparative Examples 5 and 6> An experiment was performed in the same manner as in Example 24 except that silicon and magnesium obtained by firing at 650 ° C. or 950 ° C. for 4 hours in Example 24 were used as the silicon alloy.

The results are shown in Table 1.

<Example 31> In a cylindrical separable flask having a capacity of 300 ml, 50 g of ammonia was added.
Was charged, and 9.7 g of ammonium chloride was dissolved in this.
Next, the silicon alloy containing Bi used in Example 5 was continuously added at a constant rate for 30 minutes while stirring. The amount of alloy charged is Si
As 37.0 mmol and the reaction was carried out under reflux of ammonia. Others were the same as in Example 24.

The results are shown in Table 1.

<Comparative Example 7> An experiment was performed in the same manner as in Example 31 except that silicon and magnesium obtained by firing at 650 ° C for 4 hours were used.

The results are shown in Table 1.

<Comparative Examples 8 and 9> In Example 26, a mixture of silicon, magnesium and aluminum (atomic ratio Mg / Si / Al = 2/1/1) and a mixture of silicon, magnesium, aluminum and iron (atomic ratio) Mg / Si / Al / Fe = 3/6/8/1) 65
An experiment was conducted in the same manner as in Example 26 except that the one that was baked at 0 ° C. for 4 hours was used, and the following result was obtained.

Effects of the Invention As described above, the present invention is a method for producing silicon hydride by the reaction of an alloy containing silicon and magnesium with an acid, in the alloy, IIIB, IV in the periodic table
By containing B, VB or VIB subgroup elements, the Si ₂ H ₆ yield can be significantly improved, and above all, the production ratio of SiH ₄ and Si ₂ H ₆ can be arbitrarily controlled. Therefore, the economic efficiency of the process is greatly improved.

That is, currently, in the manufacture of silicon for semiconductors, SiH ₄ and Si ₂ H _{6 which} are raw materials depending on the target performance, production scale, production speed, type of target device, etc. Unlike, it is never used equivalently. Therefore, considering the above-mentioned factors, in some cases SiH ₄ is more desirable, and in other cases Si ₂ H ₆ is more desirable. According to the present invention, in such a case, the production ratio can be arbitrarily changed according to the demand, so it must be said that its industrial significance is extremely large.

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Claims (5)

[Claims] 1. A silicon hydride represented by the general formula Si _n H _{2n + 2} (n is a positive integer of 1 or more) is produced by reacting an alloy of silicon and magnesium and an acid in a solvent. In the method, in the alloy, oxygen, nitrogen and silicon in the Periodic Table, elements IIIB, IVB, VB or VIB subgroups are added to silicon in the alloy at an addition rate (100 × additional element A method for producing silicon hydride, characterized in that the ratio (g atom number / g atom number of silicon) is in the range of 0.5% to 20%. 2. The method according to claim 1, wherein the alloy and the acid are allowed to act in a water solvent. 3. The method according to claim 1, wherein the alloy and the acid are allowed to act in a mixed solvent of an organic solvent and water. 4. The method according to claim 1, wherein the alloy and the acid are allowed to act in a solvent of ammonia or hydrazine. 5. The method according to claim 1, wherein the acid is hydrohalic acid.