Effect of axisymmetric magnetic fields on radial dopant segregation of floating-zone silicon growth in a mirror furnace

The effect of axisymmetric magnetic fields on radial dopant segregation of floating-zone silicon growth in a mirror furnace is studied through computer simulation. The mirror furnace is modeled by a point lamp model, and the magnetic fields are generated by wire coils carrying different currents. Heat and mass transfer, fluid flow, melt/solid interfaces, and the free surface are solved globally by a robust finite-volume/Newton's method. Both axial and cusp fields are considered. It is observed that the magnetic fields suppress the convection in the core region effectively, and squeeze the thermocapillary flow toward the free surface. However, due to poor mixing in the core region, large radial segregation is induced by strong magnetic fields, particularly by the cusp field. With a higher heat input, multiple steady states are also observed in weak magnetic fields.