Oxidation, Nitridation, and Fluorine Etching of Si

摘要

We summarize herein our accomplishments made possible by AFOSR Grant No. 89-0108.In particular, we carried out studies of the structure and dynamics of Si, Ge, and SiGe surfaces and interfaces, using isothermal molecular dynamics and isobaric-isothermal Monte Carlo techniques. Concomitantly, we calculated the fundamental interactions of fluorine atoms with silicon using ab initio quantum mechanics, in order to understand the mechanism of etching of silicon by fluorine. Fundamental results from those studies suggest that the surface is highly disordered during etching and that this disorder is produced from the energy released during the extremely exothermic reaction of F atoms with silicon. In order to understand oxidation and nitridation of silicon by, H20 and NH3, we must begin by determining the nature of the interaction of H atoms with Si, since they are generated during these reactions and desorption of H atoms can be rate-limiting. We completed studies of H atom adsorption, diffusion, and desorption, learning about the complicated nature of diffusion and desorption on the Si(100) surface. We also developed two new ab initio electronic structure tools: (1) pseudospectral full configuration interaction, a method for treating electron correlation numerically and (2) a reaction barrier following method for finding transition states for chemical reactions.