Method for preparing trichlorosilane and polycrystalline silicon by transforming silicon tetrachloride

Abstract

The invention aims at the problems of low one-time conversion rate, high energy consumption and large equipment investment in the conversion from the environment-polluted SiCl4 obtained in the process of the polysilicon industrial production to SiHCl3 used for the polysilicon production material by adopting the heat hydride process and much lower economic benefit of the white carbon black production using SiCl4 than that of the polysilicon. The invention provides enterprises with a SiCl4 conversion method for preparing SiHCl3 and polysilicon, which includes loading hydrogen or mixed gas of hydrogen and argon as the plasma working gas into a plasma generator, forming hot plasma jet flow at a temperature of higher than 4,000 K by arc discharge under the strong electric field, and inducing SiCl4 in a reactor to perform the reduction reaction for converting SiCl4 into SiHCl3 and polysilicon. The conversion method has the outstanding advantages of improved process, low energy consumption, and equipment investment, with SiHCl3 as main product, polysilicon as co-product and HCl as byproduct, the method further effectively prevents environmental pollution of silicon tetrachloride and increases the economic benefit.

Description

technical field [0001] The invention belongs to the technical field of non-ferrous metals and chemical technology, in particular to a method for preparing trichlorosilane and polysilicon from silicon tetrachloride, in particular to a plasma-induced hydrogen and SiCl 4 A reduction reaction occurs, the SiCl 4 Convert to SiHCl 3 , polysilicon and HCl methods. technical background [0002] At present, the improved Siemens method is the mainstream process for polysilicon production at home and abroad. With the rapid development of the photovoltaic industry, high-purity polysilicon as a raw material for solar cells has become a very important semiconductor material, and many polysilicon projects in various places have been put into production one after another. Silicon tetrachloride is the main by-product of polysilicon production in this process. Every ton of polycrystalline silicon will produce more than 10 tons of silicon tetrachloride. Since there is no large-scale, effic...

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Problems solved by technology

[0009] The object of the present invention is to: aim at the SiCl that pollutes the environment in the polysilicon process of industrial production at present 4 , using thermal hydrogenation to convert it into polysilicon raw material SiHCl 3 , there are shortcomings such as low primary conversion rate, high energy consumption, and large equipment investment, and the use of SiCl 4 The economic benefit of producing white carbon black is far lower than that of polysilicon, providing enterprises with a mature process, low energy consumption, small equipment investment, eliminating environmental pollution from silicon tetrachloride, and mainly producing SiHCl with silicon tetrachloride as raw material 3 , co-production of polysilicon, by-product HCl process, referred to as the conversion of silicon tetrachloride to prepare SiHCl 3 and polysilicon method

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