A kind of preparation method of polysilicon

Abstract

The invention relates to a preparation method of polycrystalline silicon. The method comprises the following steps: (1) preparing zinc steam; (2) preparing trichlorosilane / silicon tetrachloride steam; (3) enabling the zinc steam and the trichlorosilane / silicon tetrachloride steam to perform chemical deposition reaction on the surface of a silicon core rod to generate solid-phase silicon and produce tail gas A; (4) lowering the temperature and separating the tail gas A to get tail gas B and liquid zinc chloride; (5) lowering the temperature and separating the tail gas B to get tail gas C and liquid trichlorosilane / silicon tetrachloride; (6) inputting the tail gas C and the silicon tetrachloride to an HCL absorption tower, and absorbing hydrogen chloride by spraying the silicon tetrachloride to get the silicon tetrachloride with the hydrogen chloride; (7) heating, resolving and separating the silicon tetrachloride with the hydrogen chloride to get the hydrogen chloride and the silicon tetrachloride; (8) enabling the hydrogen chloride to react with silicon powder to get the trichlorosilane / silicon tetrachloride after purification and separation; (9) repeating the steps (2)-(8); and (10) lowering the temperature of the silicon core rod after the diameter of the silicon core rod achieves 120-180mm to get the polycrystalline silicon. The preparation method disclosed by the invention is simple in process route and can realize continuous reaction.

Description

technical field [0001] The invention relates to the technical field of polysilicon, in particular to a method for preparing polysilicon. Background technique [0002] At present, polysilicon is produced by the reaction of gaseous zinc and silicon tetrachloride. The main process is as follows: metal zinc particles pass through a melter gasifier into zinc vapor, and are brought into a tubular reactor under the conditions of protective gas and carrier gas. , Silicon tetrachloride is slowly introduced into the tubular reactor in gaseous form and reacts with zinc after gasification. The resulting silicon powder particles and zinc chloride by-products are driven by argon into the cooling depositor for cooling and deposition. The silicon powder particles and zinc chloride obtained by cooling deposition are collected by a silicon powder collector, and after pickling and vacuum freeze-drying, the silicon powder particles are obtained. Silicon powder particles are drawn into polycrys...

AI Technical Summary

Problems solved by technology

[0003] This method has the following disadvantages: the reaction between gaseous zinc and silicon tetrachloride is placed in the reaction container, which can only be placed once at a time. It cannot be carried out continuously, and the silicon powder particles must be obtained first, and then the particles are melted and drawn into polysilicon rods, so the process is complicated

[0004] The existing technology of using gaseous zinc and silicon tetrachloride to react to produce polysilicon cannot directly obtain polysilicon rods through continuous reaction. The existing technology first obtains silicon powder particles, melts the particles and then draws them into polysilicon rods. The process is relatively complicated.

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