The effect of RF sputter etching on the (111) surface of silicon was studied by observing backscatter spectra from a 2 MeV, 4He + beam oriented along the silicon <111> channel. Silicon samples were RF sputter etched in a 5 × 10 -3 torr, argon discharge at electrode bias potentials ranging from 0.5 to 2.5 kV. The samples were sputter etched for a time sufficient for the lattice damage to reach saturation. Analysis of these samples revealed that the thickness of this damage layer and the concentration of trapped argon increased with electrode bias potential. An annealing study of these damaged surfaces was carried out to 900°C.