Numerical analysis of melt/solid interface shape in zone melting recrystallization process

Abstract

Two-dimensional pseudo-steady-state model for zone melting recrystallization has been developed in which conduction in solid and molten silicon and SiO2, convection in molten silicon and radiation are included. Numerical solutions of the model equation by finite element method include flow field in the molten zone, temperature field in the full silicon-on-insulator structure and the location of solid/liquid interface in the silicon thin film and silicon substrate. One-dimensional assumption used previously has been found to be almost valid but nonplanar melt/solid interface shape necessitates the use of higher-dimensional model. The effects of the various system parameter were investigated. As the upper lamp peak intensity was increased, maximum temperature, flow intensity and the molten zone width increased linearly. The increase of the upper lamp peak intensity flattens the interface especially in the silicon substrate. As the scanning speed was increased, the symmetry of the temperature and flow field was broken, so that the curvature of the right-hand-side interface in the molten zone of the silicon substrate increased and that of the left-hand side decreased. The emissivities of the liquid and solid silicon dependent on the capping oxide thickness influenced theta(max),psi(max) and molten zone width to have the maximum value. As the heat transfer coefficient to the ambient was increased, the curvature of the interface increased due to the increase of the heat loss on the top and bottom side.