Coating And Diffusion Studies To Improve The Performance Of Silica Glass Crucibles Of The Preparation Of Semi Conducting Silicon Single Crystals

Silicon semiconductor material is pulled in the Czochralski process using silica glass crucibles. To enlarge the diameter of these Si crystals, both the quality and the performance of the crucibles have to be enhanced. Different crucibles behave differently, especially with respect to the formation of so-called CVD cristobalite, from which SiO2 particualtes are released and enter the silicon melt. The inner surfaces of silica glass crucibles were investigated by high resolution AFM and details of the CVD cristobalite formation mechanism were also studied. However, since the reasons for the differing behaviour of different industrial crucibles could not be elucidated with certainty, a suitable sol-gel dip process was developed which enables the inner crucible surface to be coated with a Ba-containing layer.