Polycrystalline silicon producing device and process

Abstract

The invention provides a polycrystalline silicon producing device, comprising a trichlorosilane synthesis furnace, a trichlorosilane reduction furnace, a silicon tetrachloride hydrogenation furnace, a trichlorosilane synthesis tail gas recycling device and a trichlorosilane reduction tail gas recycling device, wherein the tail gas outlet of the silicon tetrachloride hydrogenation furnace is connected with the feeding hole of the trichlorosilane synthesis furnace, and the air inlet of the trichlorosilane reduction tail gas recycling device is connected with the air outlet of the trichlorosilane reduction furnace. In the invention, the tail gas outlet of the silicon tetrachloride hydrogenation furnace is connected with the feeding hole of the trichlorosilane synthesis furnace, and tail gas produced by silicon tetrachloride hydrogenation directly enters the trichlorosilane synthesis furnace, thus achieving high yield of trichlorosilane and higher purity of polycrystalline product, avoiding discharge of massive impurity of chlorosilane, saving raw material and eliminating a film pressing machine, a liquid chlorine gasification device and a hydrogen chloride synthesis device; meanwhile, the whole production technological process is a material closed-loop circulation formed by silicon tetrachloride hydrogenation and trichlorosilane reduction, and no waste is discharged, thus being beneficial to environmental protection.

Description

technical field [0001] The invention relates to the field of polysilicon production, in particular to a polysilicon production device, and also to a polysilicon production process using the polysilicon production device. Background technique [0002] Please refer to figure 1 , figure 1 It is a traditional improved Siemens polysilicon production process. The specific production process is as follows: [0003] Smelt and purify quartz sand to 98% in an electric arc furnace, and use it to produce industrial silicon. The chemical reaction equation is: SiO 2 +C→Si+CO 2 ↑. [0004] In order to meet the requirement of high purity, further purification is necessary. After pulverizing industrial silicon, it reacts with anhydrous hydrogen chloride in a fluidized bed reactor to synthesize trichlorosilane to be dissolved. The reaction equation is: Si+3HCl→SiHCl 3 +H 2 ↑, the tail gas generated by the reaction is H 2 , HCl, SiHCl 3 、SiCl 4 , Si gaseous mixture. [0005] The ta...

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Problems solved by technology

[0009] In the above polysilicon production process, the tail gas of the hydrogenation reaction of silicon tetrachloride and the tail gas of the reduction reaction of trichlorosilane are recovered together, wherein the hydrogenation reaction of silicon tetrachloride is carried out in a hydrogenation furnace, and the heating element in the hydrogenation furnace is carbon -Carbon composite material or graphite is difficult to purify due to its large volume, which leads to the continuous introduction of a large amount of carbon and other impurities into the high-purity system by the heating element. In each process, the quality of polysilicon is affected, and in order to improve product quality, the amount of impurities in the chlorosilane fractionation and purification system will be increased, resulting in a large amount of impurity chlorosilane, thereby increasing the consumption of raw material silicon powder and liquid chlorine

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