Numerical Simulation of Non-Equilibrium, Ultra-Rapid Heating of Si-thin films by Nanosecond-Pulse Excimer Lasers

Abstract

In this paper we present our work on the numerical simulation of ultrarapid heating (with phase-change) of silicon thin-films, which are irradiated with nanosecond-pulsed excimer laser. Our excimer-laserannealing (ELA) modeling capability is based on a standard finite-element CFD software package, which, however, has been modified to accommodate the specific demands of very rapid heating of thin Si films. In that sense, we've abandoned the traditional equilibrium formulation (i.e. enthalpy method), for phase-change computations, and have adopted a new approach that allows superheated solid and undercooled liquid to exist during the various stages of the heating/cooling cycle. Our model has been successfully applied to predict the shape and temporal evolution of temperature profiles in the case of localized melting of silicon thin-films by excimer laser irradiation. Such scenario corresponds to conditions typically encountered in laser-induced lateral crystallization of a-Si films, a process that has recently attracted attention for the formation of high quality poly-Si films.