Influence of Crucible Shape on Thermal Field and Flow Field During Directional Solidification of Polysilicon

The impacts of three crucibles with different shapes(circular, concave as well as inverted conical) on thermal field and flow field during directional solidification of polysilicon were studied by using Comsol Multiphysics software. The results show that the differences of the thermal field of melt inside the crucibles with round and bottom concave are not obvious. However,compared with the two kinds of crucible, inverted conical crucible can achieve more even thermal field distribution and flat solid fluid interface. Heat convection are basically the same in the regions of bottom and side wall of the melt inside three kinds of crucible, but it is not different in the central regions. Heat convection is feeble in the central regions of circular and concave crucibles, however, it is stronger in the inverted conical crucible, which is beneficial to the discharge of the melt inpurity to a certain extent.