SURFACE AND IN-DEPTH CHEMICAL CHARACTERIZATION OF SPUTTER-DEPOSITED CR-SI-O LAYERS BY XPS AND AES TECHNIQUES

RF-sputtered Cr-Si-O cermet films deposited without and with a bias (200 V) have been studied by XPS and AES. Samples as deposited, etched by HF solution as well as annealed at temperatures up to 600-degrees-C have been considered. XPS results showed that the surface of the as-received samples were depleted in Cr and enriched in O with respect to the target composition. Silicon and Cr were present in both oxidized and reduced forms in the surface layer. Ar+ ion sputter profiles revealed that the composition of the subsurface approached that of the target and that Cr was present in the subsurface in reduced and Si in both oxidized and reduced states. AES in-depth profiling resulted in element concentration trends similar to but element ratios different from those observed by XPS. This was attributed to preferential sputtering coupled with the significantly different sampling depths of the two techniques. Cr3Si was identified by x-ray diffraction in samples treated at 600-degrees-C, but not even traces of it could be detected by this method below 400-degrees-C. The Si Auger parameter determined by XPS proved to be more sensitive in identifying silicide-type bonds in the Cr-Si-O layers studied.