A METHOD AND SYSTEM FOR REMOVING IMPURITIES FROM LOW-GRADE CRYSTALLINE SILICON WAFERS

摘要

Techniques are here disclosed for a solar cell pre-processing. The method and system remove impurities from low-grade crystalline semiconductor wafers and include forming a low- grade semiconductor wafer having a substrate having high impurity content. The process and system damage at least one surface of the semiconductor wafer either in the semiconductor wafer forming step or in a separate step to form a region on the surface that includes a plurality of gettering centers. The gettering centers attract impurities from the substrate during subsequent processing. The subsequent processes include diffusing impurities from the substrate using a phosphorus gettering process that includes impregnating the surface with a phosphorus material for facilitating the formation of impurity clusters associated with the gettering centers. Then, the process and system remove from a portion having the impregnated phosphorus material and the impurity clusters, thereby yielding a semiconductor wafer having a substrate having a generally reduced impurity content.