Quantitative depth profiling of an alternating Pt/Co multilayer and a Pt-Co alloy multilayer by SIMS using a Buckminsterfullerene (C60) source

A Buckminsterfullerene ion beam has been applied to the depth profiling of an alternating pure Pt and pure Co multilayer. Quantitative depth profiling was performed by secondary ion mass spectrometry (SIMS) with C60 ions using Pt-Co alloy films with different compositions. Relative sensitivity factors (RSFs) derived from a Pt39Co61 alloy film were used to convert an original depth profile to a composition depth profile. A severe interface artifact observed in the depth profile of a Pt/Co multilayer was quantitatively correlated with a gradual variation of matrix composition through the Pt/Co and Co/Pt interfaces by comparison with the depth profiling of an alloy multilayer film. Moreover, the interface artifact could be compensated by conversion of the profile to a composition profile using the same RSFs. The depth resolutions of a Pt/Co multilayer derived from the composition depth profile were much larger than the apparent interface widths measured from the original depth profile due to the nonlinear relationship between the Co and Pt ion intensities and their compositions.