Nonlinear sputtering effects in thin metal films

The sputtering yields of Ag, Au, and Pt have been measured for monatomic and polyatomic ions of P, As, Sb, and Bi over the energy range 15–135 keV. Very lare enhancements of the sputtering yields over those predicted by linear cascade theory have been observed. These enhancements appear to be consistent with a strong contribution resulting from the near-surface region of the impact area and that the complete collision cascade, even for high energy densities, plays a lesser and possibly minor role. It is also shown that the enhancements can in no way be explained based upon a thermal model in which the localized high-temperature zone is responsible for an evaporation component.