Investigation of asymmetry effects in a heater-magnet module for TMF VGF and LEC growth by three-dimensional numerical modeling

Three-dimensional (3D) electromagnetic computer modeling is used to analyze the effects of asymmetry at the crystal growth by the vertical gradient freeze (VGF) and liquid encapsulation Czochralski (LEC) methods under traveling magnetic fields (TMF). Based on the results a heater-magnet module (HMM), combining the generation of heat and induction of magnetic field, was developed and optimized. It will be shown that asymmetry effects are caused by the designs of the heater-magnet coils and bus bars. They are enforced when a TMF of higher frequencies is used. It can be concluded that for VGF arrangements without container rotation the module design must be modified. Compared to that in case of LEC the effect of asymmetry can be effectively graduated by crucible and crystal rotations.