Preferential sputtering of Cu-Ni alloys at low temperature using lower energy auger electron spectra∗

Abstract

The surface composition of Cu-Ni alloys sputtered sufficiently by Ar + ions are evaluated by AES at room temperature, and also at low (~-150°C) temperature at which the thermal diffusion of the constituent elements to the surface is ignored. The small difference of the surface concentration at each temperature shows that the diffusion enhancement by ion bombardment is small in the preferential sputtering of Cu-Ni alloys at room temperature. The depth of the altered layers of Cu-Ni alloys caused by preferential sputtering was estimated using lower (~100 eV) and higher (700–1000 eV) energy Auger spectra which have different escape dephts. The surface concentration calibrated by the lower energy Auger peaks, which overlap each other, are determined using a calibration curve obtained by the coevaporated Cu-Ni standard samples. The difference between the surface compositions determined by lower and higher energy Auger spectra is very small. This suggests that the depth of the altered layer is larger than the escape depth of Auger electrons (~15 Å).