Sputtering yields calculations of thin gold films bombarded with 175 keV argon ions — effects of surface binding and displacement threshold energies

Abstract

EVOLVE simulation results of sputtering processes of Au films with 175 keV Ar ions are compared to available experimental results. Thicknesses of Au films are 23, 99 and 192 nm, which are small, comparable and large, respectively, compared to the range of Ar ions. As a result of dose-dependent analysis of Au films, a good agreement has been found if the displacement threshold energy of Au is assumed to be 12 eV. Reducing the surface binding energy of Au from 3.8 to 1.9 or even to 0.0 eV does not increase the sputtering yield as the elemental sputtering yield formula predicts. In fact, it has no significant effect at all on the sputtering yield if the elemental value, e.g. 36 eV, is used for the displacement threshold energy of Au. On the other hand, reducing the displacement threshold energy from 36 to 12 eV increases the sputtering yield by more than a factor of 2. The sputtering yield is expressed and discussed in terms of parametric relationships of the surface binding energy, displacement threshold energy, the film thickness and the fluence.