INTERLABORATORY COMPARISON OF THE DEPTH RESOLUTION IN SPUTTER DEPTH PROFILING OF NI/CR MULTILAYERS WITH AND WITHOUT SAMPLE ROTATION USING AES, XPS AND SIMS

In order to provide a consistent judgment on the capabilities and limitations of the sample rotation approach to depth profiling, a round robin (interlaboratory comparison) was organized between four laboratories on identical samples using AES, XPS and SIMS. The sample consisted of an Ni/Cr multilayer with a total of 16 alternating Ni and Cr layers with a single layer thickness of 30 nm. Sputter profiling was performed with a rastered beam of 3 keV Ar+ ions at an incidence angle of 45-degrees to the surface normal, with and without sample rotation. Test runs were additionally performed with BCR standard samples of 30 nm thick Ta2O5 layers on Ta. For sample rotation, depth profiles of the Ni/Cr multilayer by AES and SIMS show a marked improvement in depth resolution of about a factor of two for lower sputter depth (30 nm) and four to five for greater sputter depth (450 nm). The depth resolution deteriorates with depth for stationary samples, but is found to be independent of depth when using sample rotation. For XFS, the depth resolution improvement for sample rotation is less pronounced. Agreement between the different laboratories and techniques is excellent and clearly demonstrates the capabilities of sample rotation in depth profiling studies.