Molecular dynamics simulations of Si etching by energetic CF3+

The development of a Tersoff-type empirical interatomic potential energy function (PEF) for the Si-C-F system is reported. As a first application of this potential, etching of a:Si by CF3+ using molecular dynamics (MD) simulations is demonstrated. Aspects of CF3+ ion bombardment through a fluence of 4 x 10(16) cm(-2) are discussed, including overlayer composition and thickness, Si etch yields, and etch product distributions. The formation of a 1-nm-thick steady-state SixCyFz overlayer occurs in the simulation, and this layer is an active participant in the etching of the underlying Si. At an ion energy of 100 eV, a steady state the etch yield of Si is predicted to be 0.06 +/- 0.01 Si/ion. A comparison of the simulation findings and experimental results from the literature leads to the conclusion that the new PEF performs well in qualitatively modeling the atomic-scale processes involved in CF3+ ion beam etching of Si. Simulations of this kind yield insight into fluorocarbon etch mechanisms, and ultimately will result in phenomenological models of etching by fluorocarbon plasmas. (C) 1999 American Institute of Physics. [S0021-8979(99)02723-1].