Study of silicon melt convection during the RF-FZ single crystal growth process

摘要

Flow and temperature fields in silicon melt during the floating zone (FZ) crystal growth process have been investigated both numerically and experimentally. The main purpose of the study is to clarify the effect of radio frequency (RF) heating, which is widely used in industry, on the flow and temperature fields in the melt. On the numerical study, we have made a model of RF heating and calculated the experimental situation. Further, we have also performed the numerical calculation for the radiative heating case and compared each other. On the experimental study, we have visualized a flow field by using a RF-FZ furnace with real silicon and an X-ray radiography system. The result reveals that the RF induced convection becomes dominant and the direction is opposite to the Marangoni convection. Further, the magnitude of the convection becomes one order high compared to the radiative heating case. On the other hand, strong timewise fluctuation of flow and temperature fields are obtained. This fluctuation seems to cause a strong striation in the crystal.