QUARTZ GLASS CRUCIBLE FOR PULING SINGLE CRYSTAL AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To extremely reduce impurity concentration in the inner layer in a quartz crucible for pulling silicon single crystal, having outer layer comporting a natural quarts glass layer and inner layer formed in the inside of the outer layer and comprising a synthetic quartz glass layer. SOLUTION: A layer 4a for preventing impurity of an alkali metal, etc., contained in an outer layer 1 from moving into the inner layer 4 of a synthetic quartz glass is formed between the outer layer and the inner layer of the quartz glass. Natural quartz powder is charged unto an upper opening mold 1 and the powder is molded in layers along the inside of the mold 1 to form a pre-molded body and natural quarts powder is partially melted and the melt is cooled and solidified to form a crucible substrate having translucent quartz glass layer. High-temperature gas atmosphere is formed in the interior of the crucible substrate and synthetic quartz powder containing aluminum is fed into the quartz and the powder is melted to form a quartz glass layer 4a for preventing movement of impurity having high aluminum concentration along the inner wall face 1a of the crucible substrate. Then, the synthetic quartz powder is fed into high-temperature gas atmosphere to form the inner layer 4.