Semiconductor crystal pulling system - using heat shield near fused zone for lower temp. gradient

摘要

In a crucible-free zone melting process, the seed crystal with the recrystallised bar is pulled down from a fused zone at the semiconductor stock bar. The fused zone is maintained by an inductive heating coil. A heat shield which can be moved up to within a few mm from the coil to surround the recrystallised bar is made of a thermally stable heat insulating material. Keeps the temp. gradient beyond the fused zone low. The heat input required is reduced to an optimum value. The lower internal temps. result in a longer working life of the expensive equipment for large semiconductor bar pulling.