  Factor Analysis has proved to be a powerful tool for the full exploitation of
the chemical information included in the peak shapes and peak positions of
spectra measured by AES depth profiling. Due to its ability to extract the
number of independent chemical components, their spectra and their depth
distributions, its information content exceeds the one of the usual
peak-to-peak height evaluation of AES depth profile data. Using modern software
with a graphically interactive user interface the analyst is put into a
position, where he can work with Factor Analysis on a physically intuitive
level despite of all the matrix algebra mathematics which it is based upon. The
progress brought about by Factor Analysis to AES depth profiles of thin films
is demonstrated by the analysis of two thin film systems. The first one is a
Pt/Ti metallisation used as bottom electrode for ferroelectric thin films, the
second one is multilayer system where a Ti silicide formation of burried Ti/Si
bilayers has been induced. Both examples show that Factor Analysis evaluation
of AES depth profile data is capable to give access to stoichiometry
information and to reveal interfacial layer phases, information which is hardly
obtained from the conventional peak-to-peak height data evaluation.
