PROCESS FOR PRODUCTION OF SILICON FOR USE IN SOLAR CELLS Russian patent published in 2000 - IPC

FIELD: silicon production. SUBSTANCE: molten silica is reduced with carbon to yield metallurgical silicon melt, which is powered into mold and gradually cooled to solid state. Height-to-area ratio is determined from inequality: H/(S/π)^1/2 ≥ 0.4, wherein H is height of liquid surface and S is mean area of cross-section of mold. As silicon cools, surface of liquid is heated or insulated to slow down hardening and ensure preliminary purification of silicon. Resulting silicon is remelted and refined. Phosphorus is removed by melting under reduced pressure. Boron is removed by bringing product into contact with gaseous mixture of acidic and inert gases. Oxygen is removed in deoxidation operation. Refined silicon is cast into bars. Bar is purified from iron, aluminum, titanium, and calcium by zone melting. Product is fit for manufacturing solar cells. EFFECT: increased silicon purity. 10 cl, 15 dwg, 5 tbl, 5 ex