Removal of Phosphorus and Antimony in Silicon by Electron Beam Melting at Low Vacuum

Abstract

The removal of phosphorus and antimony from molten silicon under low vacuum conditions has been investigated by using a glow discharge electron gun. The gun could generate electron beam and melt silicon at the low vacuum of 5-7 Pa. Phosphorus and antimony in silicon were evaporated and removed from silicon by the electron beam melting: the concentration of phosphorus decreased from about 200 ppm to about 1 ppm in one hour and that of antimony was reduced from about 300 ppm to below 0.1 ppm in 5 minutes. The removal rates obtained at the low vacuum were almost the same as those observed under high vacuum conditions.