Study of Transparent Layer by Type of SiO₂ Raw Material of Quartz Glass Crucible

Quartz crucible for manufacturing silicon ingots has a two-layer structure with inner and outer layer. The inner layer, which is in direct contact with the molten silicon, should minimize silicon contamination due to incorporation of impurities and crucible fragments. Therefore, a high-pure SiO₂ synthetic raw powder had been used. In this study, crucibles were prepared using the three types of high-pure SiO₂ synthetic powder; (1) powder produced by crushing and heat-treating the gel manufactured by the sol-gel method (2) powder manufactured by sol-gel method, crushed and heat-treated (3) powder produced by water glass ion exchange method, crushed and heat-treated. Both the synthetic powder had a purity of 6 N and a particle size of D₅₀ 70 to 160μm, and the microstructure of the powder showed a difference depending on the production method. Therefore, there was a difference in the distribution of bubbles generated in the transparent layer of the crucible. We also confirmed the possible effect on ingot quality as the number of bubbles in the transparent layer increases.