Interlaboratory comparison of the depth resolution in sputter depth profiling of Ni/Cr multilayers with and without sample rotation using AES, XPS, and SIMS

Abstract

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 om. Sputter profiling was performed with a rastered beam of 3 keV Ar' ions at an incidence angle of 45" to the surface normal, with and without sample rotation. Test runs were additionally performed with BCR standard samples of 30 om thick Ta,O, 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 om). The depth resolution deteriorates with depth for stationary samples, but is found to be independent of depth when using sample rotation. For XPS, 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.

Depth resolution in sputter depth profiling-characterization of a third batch of tantalum pentoxide on tantalum certified reference material by AES and SIMS

“…Similar results to those for TaO C and Ta C were observed in the inter-laboratory study reported by Hofmann et al 24 using 3 keV argon ions. Depth resolutions, z, of ¾1 nm were also found by Franzreb et al 25 in the SIMS of this system but here a 4 keV Cs beam was used and TaCs C or CsO C was detected.…”

An accurate semi‐empirical equation for sputtering yields I: for argon ions

“…The observations of severe cone formation 36 -38 generally only occur for high-energy ions or for polyatomic samples such as InP, 39 where preferential sputtering and phase separation may occur. There is still some debate as to whether the roughness should increase or decrease the measured yield but comparison of the profiles obtained with and without rotation by Hofmann et al 34,35 where smooth and rough surfaces develop, respectively, show that any effect is below the measurement precision of 3%.…”

Use of C60 cluster projectiles for sputter depth profiling of polycrystalline metals

“…8 Various surface analytical techniques such as secondary ion (neutral) mass spectrometry (SIMS or SNMS), 9 Auger electron spectroscopy (AES) 10 and x-ray photoelectron spectroscopy (XPS) 11 have been employed to characterize the actual surface exposed during continued ion bombardment. It has been shown that a depth resolution of the order of several nanometres can be achieved and maintained throughout several 100 nm of eroded depth if low-energy ions are used under non-normal incidence conditions.…”