ROLLERS CONTROL COOLING OF SILICON MELT TO FORM SILICA COLUMNAR RODS

摘要

A process and apparatus for the manufacture of silicon rods having a columnar structure comprising monocrystalline crystal zones with a crystallographic preferred orientation. Molten silicon is transferred from a silicon reservoir into a crystallization chamber which is formed by rollers arranged in a leak-proof manner in the shape of the desired rod cross-section. There the silicon first forms a stable outer shell of solidified material and, while it continues to crystallize, it is withdrawn at the bottom and released by the rollers. Owing to the short period of contact with a vessel wall a silicon rod is obtained that is particularly free of impurites.