METHOD OF PRODUCING POLYCRYSTALLINE SILICON INGOTS Russian patent published in 2012 - IPC C01B33/37 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of purifying silicon using plasma technology during industrial production of silicon for photoelectronic industry, as well as for making solar panels. The method involves heating crude silicon in a crucible until a melt is obtained and treating the melt with a plasma jet containing an inert gas and water vapour. The crude silicon is heated and melted in a vacuum using a graphite heater. The silicon is put into a rectangular quartz crucible. The silicon melt is treated with a wet argon plasma jet, directed at an acute angle to the surface of the melt. Temperature of the bottom of the crucible is controlled using an optical pyrometre. The degree of purity is controlled by sampling using a special probe. Polycrystalline silicon ingots are formed by slowly cooling the melt in the quartz crucible.

EFFECT: obtaining from metallurgical silicon with purity of 98-99,9% a polycrystalline silicon ingot of purity 99,9999% with phosphorus content of not more than 0,1 ppmw, boron content of 0,1-1 ppmw, which is suitable for industrial production of photoconverters.

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