Numerical modeling of the crystallization process in liquid phase epitaxial growth of silicon

Abstract

Numerical modeling is applied to investigate the liquid phase epitaxial growth of silicon from tin-silicon solutions in a “sandwich” cell system. The model is based on physical and numerical approaches which allow for transient computations of the solid-liquid interface shape during the crystallization process. Numerical simulations consider the thermo-solutal convection and the dependence of the solidification temperature on the liquid composition. Numerical results show that the top epitaxial layer grows faster and exhibits a wavier surface as compared to the bottom layer. The predicted layers thickness, solid-liquid interfaces shape and the growth rates are in agreement with the experimental observations. The influence of the cooling rate on the deposited layers thickness and smoothness was investigated at different liquid heights. It is found that the growth from wide liquid solutions (8 mm) at high cooling rates (2°C/min) is favorable for the deposition of thick Si layers of homogeneous thickness.