JPS61205614A - Production of hexachlorodisilane - Google Patents

Abstract

PURPOSE:In producing hexachlorodisilane by lowering chlorosilane with chlorine in a fluidized bed, to prevent clogging in a device and to raise yield, by feeding separately chlorine and silicon tetrachloride as a fluidizing gas at a specific temperature reaction and using inert particles as a fluidizing medium. CONSTITUTION:Silicon tetrachloride is fed from the piping 1 to the evaporator 4. Silicon tetrachloride vapor is introduced from the piping 5 through a distribution plate at the lower part of the fluidized bed 6. The fluidized bed 6 is filled with inert particles (e.g., alumina passing 60 meshes) as a fluidizing medium. A chloropolysilane (SinCl2n+2, n>=3) and chlorine of raw materials are fed from the piping 2, and the piping 3, respectively, through the lower side of the fluidized bed to the fluidized bed. Silicon tetrachloride used as a fluidizing gas is not premixed with chlorine and not fed to the fluidized bed, but they are separately fed to the fluidized bed, so clogging of a distribution plate of the fluidizing gas is prevented. Yield is raised by controlling the reaction temperature in the fluidized bed at 250-450 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field This invention relates to a method for producing hexachlorodisilane.

For more details, please refer to Chloropoly7ran (5inC'2n+2
+n≧3) to obtain hexachlorodisilane by chlorination decomposition and lowering.

BACKGROUND OF THE INVENTION In recent years, with the development of the electronics industry, the demand for silicon for semiconductors such as polycrystalline silicon or amorphous silicon has increased rapidly.

Trichlorosilane, silicon tetrachloride, and monosilane are mainly used as raw materials for manufacturing silicon for semiconductors. On the other hand, the use of higher chlorinated silicon has also been developed, such as 5i
Production of amorphous silicon or polycrystalline silicon by thermal decomposition of nCI2n+2 (n is a number of 2 or more) (Belgium Patent No. 889523), and production of disilane by reduction of hexachlorodisilane (Journal of the Chemical Physinox (J ,Chem,Phys,)
Vol. 22, P939 (1954)), (Journal of Inorganic Chemistry)
(J, Inorg, Nucl.

Chem, ) vol, 25, P2O3 (1963))
etc. have been reported.

However, disilane Si2H6 can be produced by chemical vapor decomposition (CVD).
), when forming an amorphous silicon film by glow discharge decomposition (GD), compared to monosilane SiH4,
The film formed on the substrate has advantages such as a much faster deposition rate and excellent electrical properties, and demand is expected to increase significantly in the future as a raw material for semiconductors for solar cells. (Japanese Unexamined Patent Publication No. 56-83929).

Conventionally, hexachlorodisilane is obtained by chlorinating silicon or silicon alloys with chlorine. However, in this case, a considerable amount of silicon tetrachloride and higher chlorides higher than octachlorotrisilane are inevitably produced as by-products, so there is a problem that the yield of hexachlorodisilane, which is the target product, is low. Further, it is also possible to treat this higher chloride with alkaline water or the like and dispose of it as it is.

In that case, there was a drawback that manufacturing costs increased due to the provision of waste treatment equipment.

Furthermore, higher chlorides higher than octachlorotrisilane,
A by-product solid, which is easily presumed to be silicooxalink, is produced, but since this solid is extremely sensitive to heat or impact, it is a very dangerous substance that will ignite and burn violently even with the slightest impact. Since it is a dangerous and troublesome substance, it poses a major safety problem.

Problems to be Solved by the Invention When a metal silicon alloy or silicon is chlorinated to obtain hexachlorosifuran, chloropoly7ran (5ln) is produced as a by-product.
When chlorinating and decomposing c12n4-2 n≧3), it was difficult to eliminate clogging troubles within the apparatus, maintain high operation rate, and obtain hexachlorosifuran in high yield.

DISCLOSURE OF THE INVENTION The present inventor has conducted extensive research to solve the above-mentioned problems and has completed the present invention.

That is, the method for producing hexachlorodisilane of the present invention involves lowering chloropolysilane ("nc12n+2n≧3) with chlorine in a fluidized bed to produce hexachlorodisilane under reaction temperature conditions of 250 to 450°C. A method for producing hexachlorodisilane which is characterized in that active particles are used as a fluidizing medium, silicon tetrachloride vapor is used as a fluidizing gas, and chlorine is introduced into the fluidized bed separately from the silicon tetrachloride vapor as the fluidizing gas for chlorination. This is the manufacturing method.

Drawing description The present invention will be explained with reference to the drawings.

FIG. 1 shows one example of the method for producing hexachlorodisilane of the present invention.

Silicon tetrachloride is introduced through the piping and is supplied to the evaporator (2). Here, all silicon tetrachloride is evaporated.

It becomes steam. Silicon tetrachloride vapor is introduced from the lower part of the fluidized bed (2) through the pipe (2) through a dispersion plate.

The fluidized bed (2) is filled with 60 mesh alumina and is controlled at, for example, 350° C. by a heat transfer heater.

Raw material chloropolysilane (5 inc12n+2, n
> 3) and chlorine are introduced into the bed from the lower side of the fluidized bed via piping (■) and (■), respectively.

The lowered reaction gas within the fluidized bed is discharged to the outside of the layer through the piping.

Examples of the chloropolysilane used in the present invention include octachlorotrisilane (S+3C16), decachlorotetra-7rane (5i4C11o), dodecachloropentasilane (5isChz), and tetradecachlorohexasilane (5i4C11o).
i6C114), etc., and these can be used alone or as a mixture.

In the present invention, if the reaction temperature is less than 250°C, the decomposition rate of chloropolysilane (sin''2n+2n>3) is low and the production efficiency is poor, and if it exceeds 450°C, the decomposition rate is high but the selectivity of the target hexachlorodisilane is low. In addition, when silicon tetrachloride and chlorine used as fluidized gas are introduced into the fluidized bed, if they are mixed first, the silicon tetrachloride decomposes and blocks the fluidized gas distribution plate of the fluidized bed. However, by introducing them separately into the fluidized bed, the trouble of clogging can be avoided.Furthermore, by using inert particles such as alumina as the fluidizing medium, chloropoly7ran (S r ICI 2n-) 2/ n" 3)
The reactor can be operated without clogging even if the residual liquid in the reactor is leaked.

Effects By carrying out the method of the present invention, it becomes possible to produce useful hexachlorodisilane from roloborisilane, which has no use and is difficult to handle, as a raw material, which is extremely valuable industrially.

Example-1 100 meshes in a fluidized bed with a diameter of 40 mm and a height of 500 mH
Filled with ~250 mesh alumina 150 CC,
12 kg of silicon tetrachloride is passed through an evaporator at 350°C per hour.
Preheat to 100% and introduce into the lower part of the fluidized bed. On the other hand, 100 Nl of chlorine was supplied per hour from the side of the fluidized bed through a pipe with an inner diameter of 8 mm. Further, 3.0 kg of octachlorotrisilane was supplied per hour through separate piping with an inner diameter of 8 fflL provided on the side of the fluidized bed, and the reaction temperature in the fluidized bed was heated using an electric heater from the side of the fluidized bed so as to maintain the reaction temperature at 350°C. Four hours after the operation was thought to have reached a steady state, the log gas from one reactor was condensed in a condenser, and 12.7 kg of silicon tetrachloride/hour was found.
1 hour hexachlorosifurane, 1.4kl? of 7 octachlorotrines were obtained.

Example-2 Under exactly the same conditions as in Example-1, octachlorotrisilane/63% and decachlorotetrasilane 21% and other higher-order chloropolysilane 716 were used instead of octachlorotrisilane.
When 3.0 kg of the mixed chloropolysilane of
g of silicon tetrachloride, 0.8 kg of Hekitek aa Jinran 1.
3 kl/o of octachlorotrisilane and 1 kg of other chloropolysilane were obtained.

Comparative Example-1 When silicon tetrachloride and chlorine from the evaporator were mixed in the fluidized bed of Example-1 and introduced into one reactor while maintaining the temperature at 350'C, a porous plate with an inner diameter of 1 mm and 16 pieces was formed. However, after 3 hours it became blocked and operations had to be stopped.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing one example of the method for producing hexachlorodiazine of the present invention.

Claims (1)

[Claims] (1) Chloropolysilane (Si_nCl_2_n_+_
2, n≧3) in a fluidized bed with chlorine to produce hexachlorodisilane, the reaction temperature is 250-45
Utilizing inert particles as a fluidizing medium under a temperature condition of 0°C,
A method for producing hexachlorodisilane, characterized in that silicon tetrachloride vapor is used as a fluidizing gas, and chlorine is introduced into the fluidized bed separately from the silicon tetrachloride vapor as the fluidizing gas for chlorination.