JPS60180910A - Manufacture of silicon hydride - Google Patents

Abstract

PURPOSE:To manufacture high purity silicon hydride by reacting an alloy contg. Si with an acid in a solvent capable of dissolving silicon hydride, separating the solvent phase from the squeous acid soln. phase, and distilling the solvent phase. CONSTITUTION:An aqueous soln. of an inorg. acid such as HCl, H2SO4 or H3PO4 or an org. acid such as formic acid, acetic acid or oxalic acid adjusted to 1-50wt% concn. is poured into a vessel. A solvent having -60 deg.C-100 deg.C b.p. such as an ether compound, hydrocarbon or halogenated hydrocarbon and powder of an Si-Mg alloy such as Mg2Si are added to the aqueous soln., and they are brought into a reaction by stirring in a reducing atmosphere. Since produced silicon hydride represented by a general formula SinH2n+2 is dissolved in the solvent, the liq. reaction product is allowed to stand to separate the solvent phase contg. dissolved silicon hydride from the aqueous acid soln. phase. High purity silicon hydride such as silane is recovered in a high yield by distilling the solvent phase by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing silicon hydride represented by the general formula S in H2n+2 (n is a positive integer) by reacting an alloy containing silicon with an acid.

More specifically, the above reaction is carried out in the coexistence of at least one kind of solvent capable of dissolving silicon hydride, and after the reaction is completed, the solvent layer and the acid aqueous solution are mechanically separated and the solvent layer is distilled to dissolve the silicon hydride. The present invention relates to a method for producing recovered silicon hydride.

In recent years, with the development of the electronics industry, the demand for silicon for semiconductors has increased rapidly.

Recently, 10 g of silicon hydride S in Hz has been gaining importance as a raw material for producing silicon for semiconductors.

Especially monosilane (SiH4), disilane (Si2Ha)
Demand is expected to increase significantly in the future as a raw material for solar cells. Several methods are known for producing silicon hydride, as exemplified below.

■Production by reaction of magnesium silicide and acid aqueous solution (m reaction formula; M2Si + 4HC19-1-→
n n ■Production by reaction of magnesium silicide and ammonium halide in liquefied ammonia solvent (m reaction formulas; M
ri2S i + 4NH4CA' --→in L 1
yNH.

■Production by reduction of a silicon halide compound (an example of a reaction formula; S iCA', +L 1AllH4--1→S
iH4+L iCA't-AlCA's) ■ A method of partially hydrogenating silicon metal, chlorinated silicon, and hydrogen gas using a catalyst to produce chlorinated silicon, and disproportionating this to produce silane.

(Reaction formula; S i+S iC4+H,, -→S i
HCl3+HCl)281)1cz3;=TeS1
H2C4+s lCl.

2 S 1H2C4□5IHC13+51H3Clτ-
1112SiH3Ct=yoS i H4-1-81H2C12
Among these methods, method (2) in which the silicon alloy according to the present invention, particularly magnesium silicide, is reacted with an acid aqueous solution has long been known as the simplest manufacturing method.

Another feature is that it is known as a method for producing not only monosilane (SiH) but also higher-grade 7-ranes higher than disilane (Si2Ha). However, conventionally, this method has had the drawback that the yield of silicon hydride is extremely low. Furthermore, in this method, the by-product of silicon compounds having siloxane bonds due to side reactions cannot be avoided, and it is said that there is a limit to the conversion rate of silicon in silicon alloys to silicon hydride (Z).

Anatg, AIJp-yc, Cmm, 303.
283 (1060).

J, A, C, S, 571349 (1935)). For this reason, although the method is simple in principle, the development of an actual industrial process has been delayed. That is, if the yield of silicon hydride can be improved by the method (2), silicon hydride can be produced easily and inexpensively, which is of great industrial significance.

The present inventors have conducted intensive studies to improve the yield of silicon hydride using method (1) above, and as a result, they have arrived at the present invention. That is, the present invention provides a method for producing silicon hydride represented by the general formula 5in112n+2 (n is a positive integer of 1 or more) by reacting an alloy containing silicon with an acid aqueous solution, in which the produced silicon hydride is dissolved. The above reaction is carried out in the coexistence of at least one kind of solvent that can be separated into two layers from the acid aqueous solution, and further, after the reaction is completed, the solvent layer in which the produced silicon hydride can be dissolved and the nucleic acid aqueous solution layer are mechanically separated. The present invention relates to a method for producing silicon hydride, which includes a step of distilling the solvent layer to obtain silicon hydride.

According to the present invention, the yield of silicon hydride can be significantly increased by simple means.

The present invention will be explained in detail below.

The silicon-containing alloy used in the present invention is an alloy consisting of two or more metals containing silicon, and specific examples include M, Si, CaSi, and Ca5Si.
2゜LeS 12, M92S r Nr, M
92 S IA 11Mg2 S 12B a , Ce
Mg2S 129Mg6S 17Cul (11M,
Preferred examples include 5i6A18Fe and the like. Among these, silicon alloys containing magnesium, especially magnesium silicide Mi;! 2Si is most preferred.

Furthermore, two or more of these silicon alloys can also be used in the form of a mixture.

There is no particular restriction on the particle size of the alloy, but the finer the particle size, the better.

However, for economical and handling reasons, it is desirable that the number of meshes be in the range of 20 to 300 meshes.

Any acid can be used as long as it is soluble in water, but it usually includes inorganic acids such as hydrochloric acid, hydrobromic acid, hydrofluoric acid, sulfuric acid, and phosphoric acid, as well as formic acid, acetic acid, oxalic acid, and propionic acid. Organic acids such as acids are used. Among these, hydrochloric acid and sulfuric acid are most preferred.

Further, the acid concentration of the acid coagulation solution is not particularly limited in the present invention, but it is preferable for the acid concentration to be in the range of 1 to 50 wt% from the viewpoint of yield of silicon hydride.

In the present invention, the reaction between the above alloy and an acid aqueous solution/liquid is carried out in the coexistence of a solvent that can dissolve the produced silicon hydride and allow two-layer separation from the acid aqueous solution. The solvent used coexisting in the acid-aqueous solution is one that melts silicon hydride at a temperature of 160°C to 100°C, and that itself is changed by the reaction or exists in the system under the reaction conditions. It is preferable to use a single component or a mixture of two or more components, which is an inert component that stably exists without chemical change with other components.

Ether compounds, hydrocarbons, halogenated hydrocarbons, silicon hydrides, and organosilicon compounds are preferred as those that are stable under such reaction conditions and have the ability to dissolve silicon hydride. To explain these more specifically, an ether compound is an ether compound containing at least one C-O
-C bonds in the molecule, examples include dimethyl ether, diethyl ether, ethyl methyl ether, diropropyl ether, cyphthyl ether, ethyl-1-
Examples include chloroethyl ether and tetrahydropyran. In addition, examples of hydrocarbons include ethane, propane, n-
Furin, l-butane, n-pentane, 2-methylbutane, n-hexane, 2-methylpentane, 3-methyl-pentane, 2,2-dimethylbutane, n-hebutane, n-
Octane is an example. The most preferred halogenated hydrocarbons include fluorides, such as monochloropentafluoroethane, dichlorodifluoromethane, octafluorocyclobutane, dichlorotetrafluoroethane, dichloromonofluoromethane, trichlorofluoromethane, trichlorotrifluoroethane, and tetrachlorodifluoroethane. . Examples of silane compounds include silicon hydride such as disilane and trisilane, and organic silane compounds and organic halosilane compounds in which at least one hydrogen of silicon hydride is replaced with an alkyl group, an alkoxy group, or a halogen.
There are also the above-mentioned derivatives of siloxane compounds having S i -0-8i bonds, such as monomethylsilane, dimethylsilane, trimethylsilane, tetramethylsilane,
Diethylsilane, triethylsilane, tetraethylsilane, trimethylethylsilane, trimethylbutylsilane, dimethyldiethylsilane, hexamethyldisilane, monomethyldifluorosilane, monomethyltrifluorosilane, dimethyldifluorosilane, trimethylfluorosilane, ethyltrifluorosilane, diethyldifluorosilane Preferred examples include triethylfluorosilane, diethylfluorochlorosilane, trimethylmethoxysilane, and trimethylethoxysilane.

The above solvents are merely examples, and in short, any solvent that has a certain degree of mutual solubility with the acid aqueous solution and forms two phases and can be separated into two phases by, for example, leaving the system still after the reaction. Anything can be used.

In addition, when using gaseous substances such as the above-mentioned dimethyl ether, ethane, disilane, etc. at normal temperature and normal pressure, the reaction is carried out at low temperature or under pressure. As already mentioned, a mixture of two or more of these substances can also be used. Further, the amount of solvent used for the acid aqueous solution is not particularly limited as long as it is at least the amount that forms an acid aqueous solution layer and a solvent layer.

In the present invention, the reaction is carried out in the presence of a solvent as described above, and after the reaction is completed, the solvent layer in which the produced silicon hydride is dissolved and the acid aqueous solution are mechanically separated, and the solvent layer is distilled to obtain silicon hydride. be.

This operation will be explained below. Here, "after the reaction is completed" refers to the time after the silicon-containing alloy is reacted with an acid aqueous solution in the presence of a solvent and the alloy and/or the acid are substantially consumed. This point can be determined by observing and observing the state of the reaction solution. That is, when an alloy is reacted with an acid, it foams significantly during the reaction, but the reaction is complete when this foaming phenomenon stops. Furthermore, since the reaction is accompanied by strong heat generation, it can be judged from the state of change in the reaction temperature, that is, the fact that the reaction temperature begins to drop rapidly. Mechanical separation of the solvent layer and the acid aqueous solution means that the reaction solution is allowed to stand still at a temperature not exceeding the reaction temperature to separate the two phases, and then the solvent layer is separated by gradient separation, etc. This is an operation to separate the acid aqueous solution layer. In this case, in order to increase the separation efficiency or /' and the separation speed,
For example, conventional means such as applying ultrasonic waves to the reaction solution, passing the reaction solution through a porous filter, or using a centrifuge can also be used. Almost all of the silicon hydride has migrated to the solvent layer separated by the above operation, and only a small amount of silicon hydride remains on the acid aqueous solution layer side.

In the present invention, silicon hydride dissolved in this separated solvent layer is recovered by a normal distillation operation, so there is no acid aqueous solution that causes decomposition, and the silicon hydride produced reacts with water to form siloxane bonds. All silicon hydride can be recovered in high yield and high purity without any generation.

Next, the reaction mode will be described in more detail.

As described above, the present invention involves reacting a silicon alloy with an acid aqueous solution in the coexistence of a solvent that dissolves silicon hydride, and mechanically separating the solvent layer and the acid aqueous solution layer after the reaction is completed. The gist of this is a production method for obtaining silicon hydride by distilling a layer, and this may be carried out in any reaction mode. i.e. batch type, semi-batch type,
Any mode of continuous reaction is possible, and various methods can be adopted for charging each component into the reactor. For example, taking a batch operation as an example, a method in which an aqueous acid solution and a solvent are charged into a reactor and the alloy is gradually charged under strong stirring;
A method in which the acid aqueous solution is first charged and then the alloy and solvent are charged as they are, or the alloy is suspended in the solvent; conversely, the alloy and solvent are charged into a reactor and the acid aqueous solution is gradually charged under strong stirring. Any method can be adopted, such as the method of Similarly, various combinations are possible in the case of continuous operation.

The reaction is usually carried out under normal pressure or increased pressure, but may also be carried out under reduced pressure. The reaction temperature is from -60°C to 100°C, preferably from -40°C to 50°C. From the viewpoint of yield, it is preferable to carry out the reaction at a lower temperature, but from the viewpoint of equipment cost and utility cost, the above range is preferable. In addition, when a single component or a mixed solvent of two or more components is appropriately selected and the reaction is carried out under boiling, the reaction heat can be removed as the heat of vaporization of the solvent, so the vaporized solvent is condensed in a condenser. The rapid flow into the reactor makes it extremely easy to control the reaction temperature.

After the reaction is completed, the reaction solution is allowed to stand at a temperature not exceeding the reaction temperature to separate the solvent layer and the acid aqueous solution layer into two layers. Various conventional means can be used to increase separation efficiency and/or speed in this operation.

For example, if simply allowing the reaction solution to stand still is not sufficient to separate the two layers, methods such as applying ultrasonic waves to the reaction solution as described above, passing the reaction solution through a porous filter, or using surface-activated Coalescence of dispersed droplets can be promoted by methods such as using a liquid agent or using a centrifugal separator.

By the above method, the two-phase separated reaction solution is subjected to gradient separation to obtain a solvent layer and an acid aqueous solution layer. The resulting solvent layer contains almost all of the produced silicon hydride dissolved, and only a small amount of silicon hydride remains in the acid aqueous solution. This solvent layer is distilled in a conventional manner to separate the silicon hydride and the solvent.

Further, the acid aqueous solution is heat-treated to recover the dissolved solvent and a trace amount of silicon hydride.

As described above, by the reaction in the presence of a solvent and the distillation operation of only the solvent layer according to the present invention, the yield of silicon hydride from silicon in a silicon alloy is significantly increased. Note that if the reaction is carried out under boiling, the reaction temperature can be controlled extremely easily. The coexistence of the solvent during the reaction suppresses the decomposition of silicon hydride, and (ii) the solvent dissolves and collects the silicon hydride produced, protecting it from the acid aqueous solution that causes decomposition. , (iii) Furthermore, this is thought to be due to the fact that the solvent washes and dissolves the silicon hydride generated on the reaction surface of the silicon alloy, constantly renewing the reaction surface and facilitating the reaction with the acid. Note that this effect is remarkable because separation 1 can be carried out by distilling and separating only the solvent layer without coming into contact with the acid aqueous solution that causes decomposition.

The present invention will be explained below with reference to Examples.

<Example 1> - A separable flask with a capacity of 41 was charged with 21 of an aqueous solution of hydrochloric acid having a concentration of 20 wt% and 1000 g of diethyl ether. In a hydrogen gas atmosphere, under conditions where the above mixture is refluxing (reaction temperature 35°C), 60% of magnesium silicide is added.
(particle size 100 to 200 mesh, 782 mmol
-8i) over 200 minutes while stirring, 0.3 g
The addition was continued at a constant rate of /'min. After the reaction was completed (after the addition of magnesium silicide), the reaction solution was cooled to 0° C., left to stand, and separated into two layers. Diethyl ether summary 11 was separated and taken out of the reactor. The temperature of the acid aqueous solution layer in the reactor was raised to 80° C., and a small amount of dissolved diethyl ether was distilled off 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 of the acid aqueous solution was collected in a trap (trap (■)) cooled at the temperature of liquid nitrogen.

Next, the diethyl ether layer after the two-layer separation was distilled in a distillation column with about 3 plates, and SiH, (b, p, -112°C
) Si□He (b, p, -14,5°C) was collected in a trap (trap ω)) cooled at the liquid nitrogen temperature.

SiH4,5i21-1. dissolved in traps (I), (It') and diethyl ether after distillation. , ,
The amount of I48 in 8 dishes was analyzed and quantified by gas chromatography.

The results are shown in Table 1.

<Examples 2 to 8> Experiments were conducted in the same manner as in Example 1, except that various solvents shown in Table 1 were used instead of diethyl ether, and the reactions were conducted at the respective reaction temperatures. The results are shown in Table 1.

<Comparative Example J> In Example 1, Si was removed from an acid aqueous solution containing diethyl ether without separating the diethyl ether layer after the reaction was completed.
The procedure was carried out in the same manner as in Example 1, except that n, , 5i2H, was separated by distillation.

<Comparative Example 2> The same procedure as in Example J was carried out except that the reaction was carried out without using diethyl ether and the reaction was heated at 80° C. after the reaction was completed.

The results are shown in Table 1.

Claims (5)

[Claims] (1) In a method for producing silicon hydride represented by the general formula S in H2n+2 (n is a positive integer of 1 or more) by reacting an alloy containing silicon with an acid aqueous solution, the produced silicon hydride cannot be dissolved. , and carrying out the above reaction in the coexistence of at least one or more solvents capable of two-layer separation from the acid aqueous solution, and further mechanically separating the solvent layer in which the produced silicon hydride can be dissolved and the nucleic acid aqueous solution layer after the reaction is completed. and distilling the solvent layer to obtain silicon hydride. A method for producing silicon hydride, characterized by: (2) The method according to claim 1, wherein the silicon alloy is an alloy containing magnesium and silicon. (3) The method according to claim (1), wherein the acid aqueous solution is an aqueous solution of hydrohalic acid, sulfuric acid, phosphoric acid, or organic acid. (4) 160 in the form of a single solvent or a mixture of two or more
Claim No. 1 having a boiling point range of 100°C to 100°C
The method described in section 1). (5) The method according to claim (1), wherein the solvent is an ether compound, a hydrocarbon, a halogenated hydrocarbon, a silicon hydride, or an organosilicon compound.