Factors causing deterioration of depth resolution in Auger electron spectroscopy depth profiling of multilayered systems

We have investigated the effects of the sputter-induced roughness on the depth resolution hz and on the interface position z(c) obtained by Auger electron spectroscopy (AES) depth profiling of a Ni/Cr multilayer and of an AlAs/GaAs superlattice. We also correlated the escape depth lambda with Delta(z) and z(c). First, the sputter-induced roughness was evaluated by atomic force microscopy (AFM). Second, both Delta(z) and z(c) were evaluated quantitatively using an error function fitting method of AES, depth profiles. The AFM observation shows that the height distribution of sputter-induced roughness is approximated to first order by a Gaussian distribution and is correlated with the resolution function which depends strongly on the sputter-induced roughness. The precise measured height distribution is, however, somewhat different from the Gaussian distribution. The computational simulation using the error function approximation fitting is in good agreement with experimental results. We also estimated the escape depth lambda using the same computational simulation results. The results indicate that the error function approximation fitting is useful to evaluate Delta(z) and z(c) as a practical method, but anomalies of Delta(z) and z(c) are discernable at the specific interface. These anomalies are assumed to come from preferential sputtering. (C) 1997 American Vacuum Society.