EFFECT OF AXISYMMETRICAL MAGNETIC-FIELDS ON RADIAL DOPANT SEGREGATIONOF FLOATING-ZONE SILICON GROWTH IN A MIRROR FURNACE

The effect of axisymmetric magnetic fields on radial dopant segregatio n of floating-zone silicon growth in a mirror furnace is studied throu gh computer simulation. The mirror furnace is modeled by a point lamp model, and the magnetic fields are generated by wire coils carrying di fferent currents. Heat and mass transfer, fluid flow, melt/solid inter faces, and the free surface are solved globally by a robust finite-vol ume/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 fr ee surface. However, due to poor mixing in the core region, large radi al segregation is induced by strong magnetic fields, particularly by t he cusp field. With a higher heat input, multiple steady states are al so observed in weak magnetic fields.