An interatomic potential for reactive ion etching of Si by Cl ions

An interatomic potential has been developed to describe the dynamics of Si/ Cl systems, with particular relevance to reactive ion etching of Si by ener getic Cl ions. We have modified the Stillinger-Weber (SW) potential of Feil et al. by adding two new terms: (1) an embedding term that corrects for th e variation in Si-Cl bond strength as a function of the number of neighbors , and (2) a four-body term to describe the variation of the Si-Si bond stre ngth as a function of the number of neighbors of each Si atom and the atom types (a bond order correction). Calculated Si etch rates obtained from mol ecular dynamics simulations using the new potential are in better agreement with recent experimental results than those obtained with the unmodified p otential. Predictions of the stoichiometry of the etch products are also ma rkedly different between the two potentials. (C) 1999 American Institute of Physics. [S0021-9606(99)00803-X].