ARGON -ANNEALED 300 MM WAFERS COMPLEMENTING PP- EPITAXIAL LAYERS

摘要

Silicon wafers horizontally oriented in a vertical furnace tend to bend downwards due to gravitational stress. We have investigated ring-like wafer supports with varying geometry and surface/mechanical properties in regard of minimized gravitational stress and therefore improved slip behavior. Ring width turned out to be a crucial parameter, slip reduction was observed at ring widths ≥ 30 mm. Ring supports made of polished and coated SiC are preferred compared to polished silicon due to the high mechanical and surface stability of SiC at temperatures ～1200 ℃. Concepts known from 200 mm wafer argon anneal are e. g. nitrogen doping to enhance BMD density, reduce COP sizes and achieve a wafer hardening. This method was positively applied also for annealing of 300 mm wafers in 100 % argon ambient.