Patent ID: 8257492
Filing Date: 2012-09-04
Classification: C01B,H01L,Y02E,Y02P

Abstract:
1. A method for purifying silicon bearing materials for photovoltaic applications, the method comprising: providing metallurgical silicon into a crucible apparatus; subjecting the metallurgical silicon to at least a thermal process to cause the metallurgical silicon to change in state from a first state to a second state, the second stage being a molten state not exceeding 1500 Degrees Celsius, the power to the thermal process being provided intermittently; providing at least a purification gas towards the surface of the silicon melt through an independent supply tube, the supply of the purification gas being provided intermittently; causing at least a first portion of impurities to be removed from the metallurgical silicon in the molten state; cooling the molten metallurgical silicon from a lower region to an upper region to cause the lower region to solidify while a second portion of impurities segregate and accumulate in a liquid state region; and solidifying the liquid state region to form a resulting silicon structure having a purified region and an impurity region, whereupon the purified region is characterized by a purity of greater than 99.9999%.