Effect of ion mixing on the depth resolution of sputter depth profiling

Abstract

The effect of ion mixing on the depth resolution of sputter depth profiling has been studied using x-ray photoelectron spectroscopy and Ar+ sputtering of Pt/Zr, Pt/Mo, Pt/Ti, and Pt/Ni interfaces. It is shown that the heat of mixing of binary alloys plays an important role in depth resolution. The measured interface width of bilayers consisting of metals with a large and negative heat of mixing (Pt/Zr and Pt/Ti) is significantly broader than that of metals with a nearly zero heat of mixing (Pt/Mo and Pt/Ni). This observation suggests that the mechanism of ion mixing during sputter depth profiling with ion energies of a few keV is the same as ion mixing with ion energies of several hundred keV; diffusion in thermal spikes is the dominant contribution to ion mixing in the systems investigated.