New C-F interatomic potential for molecular dynamics simulation of fluorocarbon film formation

A new interatomic potential of fluorocarbon systems has been developed. This potential is based on Brenner's reactive empirical bond-order potential [D. W. Brenner, Phys. Rev. B 42, 9458 (1990)] for hydrocarbon systems which is a variation of Tersoff potential [J. Tersoff, Phys. Rev. Lett. 56, 632 (1986)]. A set of empirical correction functions was determined so as to reproduce the accurate atomization energies of many types of fluorocarbon molecules. To check the transferability of Tersoff-Brenner potential to ion sputtering problems, molecular dynamics simulations were conducted. We thereby studied carbon sputtering by argon ions for the first time and obtained reasonable sputtering yield compared with experimental data. The fluorocarbon film formation on an amorphous carbon surface exposed to CFx+ (x=1,2,3) bombardments was also simulated with the new C-F potential. (The ion energy was 100 eV.) CF+ impacts continued to grow carbon-rich Fluorocarbon film, but CF2+ ions formed a fluorocarbon him that was then etched down. And CF3+ ion impacts turned the deposition into etching more rapidly than CF2+. The composition of etching products changed according to the state of fluorocarbon films, and this change should be included in boundary conditions of macrolevel simulations. (C) 2000 American Vacuum Society. [S0734-2101(00)02103-5].