Quantification of AES depth profiling data of polycrystalline Al films with Gaussian and non‐Gaussian surface height distributions

Abstract

Sputtering-induced roughness is the main distortional factor on the depth resolution of measured depth profiles, in particular, for sputtering of polycrystalline metals. Frequently, the surface height distribution of the sputtering-induced roughness exhibits an asymmetrical feature. In such a case, a non-Gaussian height distribution function (HDF) has to be applied for the quantification of a measured depth profile. By replacing the usually applied Gaussian HDF with that of an asymmetrical triangle in the Mixing-Roughness-Information depth model, measured Auger electron spectroscopy depth profiling data of the interface of polycrystalline Al films on Si are perfectly fitted. The asymmetric triangle height distributions obtained from the best fit are a reasonable approximation of the height distributions measured by atomic force microscopy.

Measurement of the roughness of nano-scale surfaces, both unannealed and with limited anneal, by atomic force microscopy

“…It is often assumed that these heights describe a Gaussian distribution that, added to other contributions, controls the depth-resolution [4][5][6][7]. Non-Gaussian [8][9][10] and multiple Gaussian profiles [11] also occur, and any particular distribution may be analyzed, as discussed below. At coarser pitches, Greenwood and Williamson [12] and Whitehouse and Archard [13] show that the heights and the asperities for grit-blasted surfaces (which, in the early studies of sputtering, were taken as a useful analogue) exhibited a Gaussian population of heights in the range of up to 2 or 3 sigma from the mean heights.…”