Ion beam induced roughness and its effect in AES depth profiling of multilayer Ni/Cr thin films

Abstract

Abstract The development and changes in the surface topography during ion beam etching is described by a new model taking into account the lateral displacement and collective behaviour (annihilation) of the ‘macrostep’.The model was applied to simulate thedepth dependent surface roughening taking place at the depth profiling of Ni/Cr multilayer systems with various sputtering conditions. Crystals in a channelling position were considered as sources of macrosteps. The experiments confirmed the lack of the surface roughening predicted by the model at high incidence angle of the ion beam (θ>85°)and at sample rotation. The experimental depth resolution proved to be independent of the depth if the upper layers had been removed by presputtering in ion milling equipment at θ = 86° before the conventional Auger depth profiling was carried out. A best resolution‐ (3.2 nm) has been achieved at 225 nm depth when the sample was presputtered down to 180 nm and was also rotated during Auger profiling.