XPS imaging of depth profiles and amount of substance based on Tougaard's algorithm

Traditional XPS imaging produces a map of the XPS peak intensity. It is well known that the peak intensity carries limited information on the total amount of material as well as on the depth distribution of atoms. Such images can therefore be strongly misleading. Elaborate methods for improved quantification by analysis of the peak shape were developed by Tougaard et al. in the past but they require operator interaction and are therefore not suitable for imaging where thousands of spectra must be analyzed. Recently, Tougaard proposed a new algorithm [S. Tougaard, J. Vac. Sci. Technol. A 21 (2003) 1081] which is less accurate but sufficiently robust to allow for automatic data processing. In the present paper, we have successfully demonstrated the ability of the algorithm to produce detailed images of a plasma patterned polymer on Teflon. In general, four images are produced which show the distribution of pixels where F atoms are at the surface, in the bulk, or homogeneous in depth as well as an image of the amount of F atoms within the outermost three inelastic electron mean free paths.