Sputtering of PtSi

The sputtering of PtSi by Ar ions of 10 to 160 keV has been studied by Rutherford backscattering techniques with depth resolutions of 200 A at normal incidence and 40 A at extreme glancing angles. The surface layers of the sputtered samples become Pt enriched over depths ranging from 100 to 1600 A. For a given Ar energy, the Pt enrichment extends approximately over a constant depth and the enrichment increases with increasing Ar dose until steady state is reached. The steady-state composition ratio of Pt to Si at the surface is approx.2.0 for all energies. The sputtering yields of Si before steady state are found to be larger than those of Pt, consistent with Pt enrichment. A phenomenological model, based on preferential ejection of Si from the surface and enhanced diffusion over the range of Ar, explains the present data