PRODUCTION OF SOLAR-GRADE SILICON FROM SILICON DIOXIDE

摘要

Disclosed herein is a method for the production of pure silicon comprising the reduction of purified silicon dioxide with a pure carbon source, wherein pure silicon means a material displaying ? 5 ppm of aluminium, ? 10 ppm to 0.0001 ppt of boron, ? 2 ppm of calcium, ? 20 ppm of iron, ? 10 ppm of nickel, ?10 ppm to 0.0001 ppt phosphorus, ? 2 ppm of titanium and ? 3 ppm of zinc, purified silicon dioxide means a material displaying ? 5 ppm of aluminium, < 10 ppm to 0.0001 ppt of boron, ? 2 ppm of calcium, ? 20 ppm of iron, ? 10 ppm of nickel, < 10 ppm to 0.0001 ppt of phosphorus, ? 2 ppm of titanium and ? 3 ppm of zinc and pure carbon means a material displaying between 4 and 0.000001 ppm aluminium, 5 and 0.000001 ppm boron, 5 and 0.000001 ppm phosphorus, 100 and 0.000001 ppm iron, 20 and 0.000001 ppm sodium, 30 and 0.000001 ppm potassium, 4 and 0.000001 ppm nickel, 4 and 0.000001 ppm chromium and wherein the purified silicon dioxide is obtained by precipitation of a silicon dioxide dissolved in aqueous phase in an acidifying agent, wherein the pH value during the precipitation is less than 1 and in the absence of a chelating agent, and wherein the pure carbon source is selected from the group consisting of carbohydrate, graphite, coke, coal, carbon black and thermal black.