Superposition of Auger electron spectroscopy depth profiles obtained on Cr/Ni multilayer samples with different roughnesses

Abstract

Practical depth profiling by ion sputtering is strongly influenced by sample roughness. Auger electron spectroscopy (AES) depth profiling studies for multilayer Cr/Ni thin-film structures on rough substrates could be explained by assuming a superposition of depth profiles of many microplanes with widely different angles with respect to the ion beam direction. To test the validity of this assumption, the AES depth profiles of samples consisting of two parts with different roughnesses, Ra=0.012 μm and Ra=0.920 μm, were measured. In five subsequent experiments, the analyzed area was changed from 100% to 0% of the part with Ra=0.012 μm. The results were evaluated for the depth resolution Δz as a function of the sputtered depth z between 25 and 375 nm. Good agreement was obtained between experimental results and calculations of the total Δz as a function of the area fractions of the different roughnesses according to a linear superposition of Δz for different microplanes.