Atomic mixing and electron range effects in ultrahigh-resolution profiles of the Ta2O5/Ta interface by argon sputtering with Auger electron spectroscopy

Abstract

An assessment is made of the effects of atomic mixing and electron range on the profile shape and interface resolution measured in the composition depth profiling of elemental layers on elemental substrates, using Auger electron spectroscopy. A practical method is derived for extracting these two parameters. For compound overlayers, preferential sputtering and pileup effects are included and this can sharpen the interface, as demonstrated by measurements in the Ta₂O₅/Ta system. The profiles for oxygen show resolutions of 1.41±0.07 nm at 28.4 nm and 1.74±0.10 nm at 96.3 nm. These resolutions involve atomic mixing contributions of 0.66 and 0.83 nm, respectively, in close agreement with the predictions of Lindhard, Scharff, and Schio/tt’s theory.