New multicrystal silicon reduction production technology

Abstract

The invention relates to a new multicrystal silicon reduction production technology. In the initial stage of the reaction, by increasing the temperature, the deposition rate can be increased and the silicon rod can grow fast; as the total flow rate in the furnace is low, even the hydrogen content is low, the occurrence rate of the side reaction is relatively low; in the medium stage of the reaction, when the silicon rod grows continuously, by reducing the temperature and increasing the hydrogen content, the pyrolytic reaction and side reaction can be inhibited; by increasing the total flow rate, the reaction rate can be increased; and in the later stage of the reaction, by further increasing the hydrogen content and the flow rate and maintaining the temperature, the violent side reaction caused by the increase of the active area can be inhibited. By optimizing the reaction conditions of reduction, trichlorosilane can be effectively converted and the silicon rod can grow better; meanwhile, the pyrolytic reaction can be inhibited, the main reduction reaction can be performed better and the effect is obvious; and the by-products can be reduced and the comprehensive cost of multicrystal silicon can be reduced.

Description

A New Process for Polysilicon Reduction Production technical field The invention relates to a polysilicon production technology, in particular to a new polysilicon reduction production process. Background technique At present, the vast majority of domestic polysilicon factories use the modified Siemens method to manufacture rod-shaped polysilicon, that is, in a bell furnace, at a certain temperature and pressure, in trichlorohydrosilane and hydrogen, through chemical vapor deposition (CVD) method, high temperature Reduction of trichlorosilane to prepare rod-shaped polysilicon. Since many side reactions occur in this reduction reaction, the possible main reactions are as follows: SiHCl3+H2=Si+3HCl↑(1050-1100℃) 4SiHCl3=Si+2H2↑+3SiCl4 (thermal decomposition) 2SiHCl3=Si+2HCl↑+SiCl4 (thermal decomposition) SiHCl3=SiH2Cl2+HCl↑(900-1000℃) Si+2HCl≒SiH2Cl2 (>1200℃ or low temperature corrosion) SiHCl3=SiH2Cl2+SiCl4 (Si+SiCl4≒SiCl2) SiCl4+2H2=Si+4HCl↑ (at high temper...

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Problems solved by technology

These figures show that the reaction (2) is absolutely dominant, which not only results in inefficient utilization of the raw material trichlorosilane, increases energy consumption, but also brings a burden to the later treatment of silicon tetrachloride (even with hydrogenation)