  Depth profiling of thin films by inert gas sputtering is one of the most
important applications of Auger electron spectroscopy and X-ray photoelectron
spectroscopy. Such an analysis monitors the elemental in-depth composition of
the thin film system and controls the quality of the manufacturing process. A
challenging task of a sputter depth profile measurement is the determination of
the interface contaminations. Interface contaminations are only detectable if
the depth profile data were measured with a sufficient depth resolution.
Interface contaminations are crucial, because they strongly influence the
mechanical and electrical properties of the whole thin film system. The depth
resolution of unidirectional sputter depth profiling for polycrystalline
samples is limited by the sputter yield differences attributed to grains having
different crystalline orientations relative to the incoming ion beam. Therefore
depth resolution optimized sputter depth profiling of polycrystalline thin
films requires dedicated experimental approaches. If the sample is rotated
during ion sputtering the depth profile is recorded with a better depth
resolution because the ion impact direction relative to the grains orientation
varies. If depth profiling can be performed on a single grain only, the depth
resolution is improved, too. These approaches are applied to the depth
profiling and interface contamination analysis of a 5000 nm thick
polycrystalline Al layer. An O contamination at the interface of the Al to the
Si substrate was detected utilizing these high depth resolution depth profiling
methods.
