SPUTTER REDUCTION OF OXIDES BY ION-BOMBARDMENT DURING AUGER DEPTH PROFILE ANALYSIS

Quantification of the magnitude of preferential sputtering of oxygen from metallic oxides has been examined for a large number of 30 nm thick amorphous oxides deposited onto polished silicon substrates. The method of analysis was derivative‐mode Auger analysis carried out in a cleaner vacuum system and with cleaner initial surfaces than has been the case usually for data found in the literature. Ion sputtering was primarily with 3 keV xenon ions but the effect of ion energy (1, 3 and 4.5 keV), ion mass (argon or xenon) and sputter rate was also examined. The magnitude of preferential sputtering at 20°C was generally much less than has been reported previously and was not a function of ion energy, mass or sputter rate over the range studied. The results separate into two groups: oxides that reduce appreciably and those that do not. The results agree well with the predictions from the theoretical model of Kelly.1 It must be concluded from the work that most of the data reported in literature are primarily the result of unrecognized and therefore unreported variables. Likely candidates are contaminants within the ion beam and background environment that contribute chemical effects to the sputter process, ion beam and electron beam heating of poorly conducting samples, or redeposition of sputtered material into the analysis area. Copyright © 1990 John Wiley & Sons Ltd.