METHOD FOR MANUFACTURING QUARTZ GLASS CRUCIBLE

摘要

Methods for manufacturing a quartz glass crucible which, even when it is subjected to a high thermal load, is free from the occurrence of rupture of bubbles enclosed therein and, as a result, does not interfere with the formation of a single crystal during the pulling of a seed crystal are provided. In a method, when a raw material powder is melted in a mold (1), H2 gas and O2 gas is introduced immediately after the start of arc discharge in order to remove graphite components in an electrode and impurities in the quartz powder of a raw material, which lead to the inhibition of incorporation of such graphite components and impurities into a crucible product and results in the inhibition of expansion of the bubble and the decrease of the pressure in the inside of the bubble. Also provided is a method wherein He gas is fed from the mold (1) to a deposited layer of a quartz powder formed in the mold (1), to thereby substitute He gas for the gas in the void in the deposited layer. The substitution of the gas in the void makes bubbles in an opaque layer less prone to expansion, which leads to the prevention of decrease of the thermal conductivity of the crucible and thus to the inhibition of increase of the temperature of the crucible in use, resulting in the prevention of the rupture of bubbles in a transparent layer.