REDUCTION OF AIR POCKETS IN SILICON CRYSTALS BY AVOIDING THE INTRODUCTION OF NEARLY INSOLUBLE GASES INTO THE MELT

摘要

A process is provided for controlling the amount of insoluble gas carried by acharge of granular polycrystalline silicon. The process comprises (i) charginga feeding container with granular polycrystalline silicon, (ii) forming anambient atmosphere in the feeding container, the ambient atmosphere havinga mole fraction of at least 0.9 of a gas having a solubility in molten silicon ofat least about 5x1013 atoms/cm3 at a temperature near the melting point of siliconand at a pressure of about 1 bar (about 100 kPa), and (iii) reducing the pressureinside the charged feeding container.