The depth dependence of the depth resolution in sputter profiling

It is shown that data from different authors on the depth dependence of the depth resolution can be compared only when both the instrumental parameter (β) and the intrinsic parameter (α) are taken into account. These two essential parameters are shown to be unique for every given ‘set of instrument and sample’. A linear z‐dependence was derived in a first approximation from experimental data. In this case it is shown that a power approximation in a (log (Δz/z)vs log z) plot, can have any value for the exponent between −1 and 0, dependent on the z‐interval considered. The z‐interval for which a given value of the exponent is obtained, in turn depends on α and β. The influence of the acceptance area and the primary ion energy on the intrinsic parameter α and the influence of the beam inhomogeneity on the parameter β are discussed. The implications of a non‐linear z‐dependence on the interpretation of experimental data are considered.