PROCESS FOR THE PRODUCTION OF LOW-COST REFINED METALLURGICAL SILICON FROM METALLURGICAL GRADE SILICON

摘要

pSilicon platelets essentially free of iron are precipitated from a solution of metallurgical grade silicon in molten aluminum and are melted in contact with silica slag to produce a refined metallurgical silicon (RMS). Multigrained bouler of said RMS may be pulled by the Czochralski method on a rotating silicon seed rod from a melt of said RMS. Alternatively, the silicon-slag melt can be directionally solidified to produce a directionally solidified refined metallurgical silicon (DS/RMS) separated from a region of solidified melt having a high concentration of impurities rejected by the silicon as it solidifies, Multigrained DS/RMS boules may be pulled from a melt of said DS/RMS. Alternatively, the DS/RMS is remelted and directionally solidified a second time with single crystal DS/RMS boules being pulled from a melt of the twice directionally solidified material. The thus-pulled, jul multigrained RMS and DS/RMS and single crystal DS/RMS materials are low-cost products having a substantially higher impurity content than in conventional high purity semiconductor grade silicon while, at the same time, having desirable solar cell properties./p[CA1135941A]