Quantitative depth profiling in surface analysis: A review

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Abstract
After a brief survey of the various non‐destructive and destructive methods used for obtaining in‐depth composition profiles, the generally applicable method of ion sputtering in combination with a surface analysis technique is discussed in more detail. The quantitative evaluation of sputtering profiles requires the conversion of a measured signal intensity versus sputtering time into a true concentration versus distance from the original surface. Basically, this procedure comprises the quantification of the surface analysis method applied and the sputtering rate, both being dependent on sample composition. Furthermore, various phenomena limit the quantitative evaluation of depth profiles; the most important of which are ion and/or electron beam induced changes of surface composition and surface microtopography. Different factors such as information depth, ion beam inhomogeneity, original and beam induced roughness, knock‐on and atomic mixing effects, preferential sputtering, enhanced atomic migration etc. are discussed with respect to their influence on depth resolution and its dependence on sputter depth. Model calculations and their comparison with experimental data reveal the influence of these factors. In conclusion, the basic requirements for the optimization of sputter profiling are stated.