Numerical Modeling of Thermal and Flow Field in Directional Solidification Silicon under Vertical Magnetic Field

One of the key issues in the directional solidification (DS) process of multi-crystalline silicon (mc-Si) is to control the melt flow in order to achieve a higher quality of silicon ingot. A steady global model is developed to investigate the effects of vertical magnetic field (VMF) variation in industrial G5 DS furnace. The Solid/Liquid (S/L) interface, thermal and flow field during directional solidification of mc-Si have been simulated. The results show that, with B0 increases, the deflection of S/L interface decreases and melt flow rate is greatly inhibited. Through the analysis of the flow structure, it is found that two small vortexes in melt without B0 become a large vortex as B0 increases. The melt flow distribution is more uniform which is beneficial to obtain a homogeneous distribution of impurities. These results show the VMF can be adjusted to successfully obtain a more uniform flow distribution and a flatter S/L interface shape.