Photovoltaic Industry Polysilicon Manufacturing Technology Foundation Analysis

Photovoltaic Industry Polysilicon Manufacturing Technology Foundation Analysis

Metal silicon is the main raw material for polysilicon production. The overall purpose of solar-grade polysilicon manufacturing is to separate metal and amorphous silicon impurities such as iron, magnesium, and calcium contained in metal silicon from silicon, and finally obtain high-purity crystalline silicon crystals.

Trichlorosilane is still the most mature and economical polysilicon manufacturing solution. Trichlorosilane has certain advantages in terms of safety, storage and transportation, and is optimal in terms of useful deposition ratio and deposition rate. After continuous improvement, the production cost of electricity consumption has dropped to a level close to the silane method.

The first-generation trichlorosilane method has poor cycle utilization. Silicon tetrachloride is directly regarded as a by-product, and hydrogen chloride gas becomes a hydrochloric acid after being dissolved in water, and it is no longer used for recycling. The first-generation trichlorosilane method polysilicon production system has a very small recovery and recycling system, so the overall investment is small, but raw materials are wasted and the production cost is high. After an annual output of more than 100 tons, it is difficult to sustain.

Hot hydrogenation and cold hydrogenation have their advantages. The thermal hydrogenation energy consumption is high, but the whole reaction is a gas phase reaction, there is no wear on the equipment, the purity of the transformed trichlorosilane is high, and the automation control of the production process is relatively mature. The main advantages of cold hydrogenation are low energy consumption and low operating costs. However, it is difficult to add silica fume, and the solid-phase reaction equipment is very wearable. It is difficult to continuously and stably operate for a long period of time. The reactants are more complex and require a catalyst. The quality of hydrogen silicon production is affected. As the current domestic production of polysilicon project approval energy consumption is placed in a very important position, so the new polysilicon project is mainly cold hydrogenation.

The scale of domestic polysilicon manufacturing has greatly improved. In 2010, China's polysilicon production exceeded 40,000 tons, which was an increase of more than 200% compared to 2009, and the global share accounted for more than 25%. One of the leading enterprises GCL-Poly annual output reached 176 million tons, an increase of 139.5%. Jiangxi Seville 2009 production was only 225.1 tons, soared to 5052 tons in 2010, ranking second in the country. Asia Silicon, Yichang CSG, Sichuan Yongxiang, Chengdu Tianwei, and Ningxia Sunshine have achieved mass production.

The main sources of domestic polysilicon technology are Russia, Europe, and the United States. Russian technology can be regarded as a guide for domestic polysilicon manufacturing processes and it still plays an important role. European technology introduction costs are generally expensive but they are worth the money. U.S. technology is mixed. Domestic companies and R&D institutions are independent innovations on the basis of digesting overseas technology and show strong competitiveness.