Three-Dimensional Simulation of MHD Oscillatory Mixed Convection and Impurity Transport in Czochralski Melt Under Different Magnetic Field Configurations

The Czochralski (CZ) method is a vital technique for producing single-crystal silicon, which is the foundation of high-efficiency solar panels for renewable energy applications. However, complex melt flow dynamics and impurity transport to the crystal growth interface can lead to defects in the silicon ingot, affecting the performance of solar cells. To address these challenges, external magnetic fields are employed to control melt flow and impurity distribution. In present study, a 3D magnetohydrodynamic (MHD) mixed convection model for the CZ crystal growth process is adopted. The numerical simulations are presented for various Hartmann numbers under transverse magnetic field (TMF) and cusp magnetic field (CMF) configurations, with fixed Richardson number and Reynolds number. The melt oscillation, flow structure, and oxygen concentration under TMF and CMF configurations are compared. CMF exerts a stronger suppression of the melt fluctuation than TMF configuration at the same Hartmann number around crucible bottom area. A periodic flow behavior is observed under CMF at Ha = 20. For TMF configuration, the damping effect due to Lorentz force is mainly exhibited on locations perpendicular to the magnetic field, which causes an un-axisymmetric temperature and velocity field. Oxygen concentration under CMF is significantly reduced compared with TMF cases. An elliptical shape oxygen radial distribution is observed under TMF, and forms a θ angle with direction perpendicular to the magnetic field. Additionally, a uniform radial distribution is observed in central crystal region at high Hartmann number TMF cases. This research provides valuable insights into optimizing the CZ process for producing high-purity single-crystal silicon under magnetic field approaches, thereby enhancing the performance and reliability of single crystal silicon wafers for photovoltaic and semiconductor applications.