New solar-grade polysilicon process technology In addition to the above-mentioned improved Siemens method, silane thermal decomposition method, fluidized bed reactor furnace method to produce electronic-grade and solar-grade polysilicon, several new technologies for the production of solar-grade polysilicon have emerged. 1) Metallurgical production of solar-grade polysilicon According to data reports: the polysilicon produced by the Kawasaki Iron and Steel Company of Japan using metallurgical method has been applied in the world's largest solar cell factory (SHARP company), and has now formed a production capacity of 800 tons / year Supplied to SHARP. The main process is: select industrial silicon with better purity (ie, metallurgical silicon) to perform one-way solidification in the horizontal zone to form a silicon ingot. After removing the metal impurities in the silicon ingot and the surface part, perform coarse crushing and cleaning. In the body melting furnace, the boron impurities are removed, and then the second horizontal zone melting is unidirectionally solidified to form a silicon ingot. The second part zone of the molten silicon ingot is concentrated in the metal impurities and the outer part, after coarse crushing and cleaning, In the electron beam melting furnace, phosphorus and carbon impurities are removed, and solar-grade polysilicon is directly generated. 2) Production of granular solar-grade polysilicon by gas-liquid deposition method According to data reports [1] represented by Japan ’s Tokuyama Corporation, a 10-ton test line is currently in operation, and a 200-ton semi-trade scale production line was put into trial operation from 2005 to 2006. According to the report of Crystal Systems in the United States, after purification of silicon waste generated in the production process of heavily doped single crystal silicon, the United States can be used as polysilicon for solar cell production, and the ultimate cost can be See below $ 20 / Kg. Here is a comparison between the equipment technology of several domestic polysilicon plants and foreign polysilicon plants. Characteristics of the development of foreign polysilicon production technology: 1) The new process technology developed is almost all to meet the solar-grade polysilicon required by the solar photovoltaic silicon cell industry. 2)
