Molecular dynamics simulations of Si etching by energetic CF3+

The development of a Tersoff-type empirical interatomic potential energy fu nction (PEF) for the Si-C-F system is reported. As a first application of t his potential, etching of a:Si by CF3+ using molecular dynamics (MD) simula tions is demonstrated. Aspects of CF3+ ion bombardment through a fluence of 4 x 10(16) cm(-2) are discussed, including overlayer composition and thick ness, 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 i on 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 experime ntal results from the literature leads to the conclusion that the new PEF p erforms 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 phenomenologic al models of etching by fluorocarbon plasmas. (C) 1999 American Institute o f Physics. [S0021-8979(99)02723-1].