Auger electron spectroscopy composition depth profiling of Cr/Ni multilayer structures using Ar+ and Xe+ ions

The influence of the layer thickness of the removed layer on the depth resolution of Auger electron spectroscopy combined with ion beam profiling was studied experimentally. Argon and xenon static beams with energy E(i) = 0.9 keV were used to sputter the multilayer Cr/Ni structure. With the intention of minimizing the crater wall effects, the ion beam was optimized so that the gradient of the current density over the area covered by the primary electron beam was as small as possible and similar for both gases. The measured values of depth resolution DELTA-z, dependent on the depth sputtered off, were lower by a factor of 1.4 - 2.0 for Xe+ ions than for Ar+ ions. We believe that this difference is caused mainly by the surface microroughness induced by sputtering. The roughness induced by Ar+ ions was larger than that caused by Xe+ ions. The contribution of atomic mixing and recoil implantation was responsible, in accordance with Andersen's model of cascade mixing, only for a negligible part of the difference in depth resolutions observed with Ar+ and Xe+ ions.