A numerical parameter study on the occurrence of bulk circulating flow in Si HMCz crystal growth

This paper presents a parameter study of the melt flow dynamics during growth of 300 mm Si crystals by the HMCz technique. A local, time-dependent 3D model was used to calculate the convective heat transport of a 185 kg heavy Si melt in a 32″ crucible considering a LES turbulence model. The objective of this study was to get a deeper understanding of the occurrence of the bulk circulating flow consisting of one big vortex instead of the two symmetrical vortices which was sometimes reported in literature. It is found that the magnetic field strength, the crystal rotation and the shear stress at the free melt surface induced by the argon gas play a significant role in this process. Increasing the crystal rotation or decreasing the magnetic field strength will promote the occurrence of the bulk circulating flow. The shear stress on the free melt surface will affect the flow regime as well. Without shear stress at the free melt surface, no bulk circulation occurs in the considered parameter range.