Characterization of plasma treated Al-Films by GIXR and GIXRD

The combination of grazing incidence x-ray reflectometry (GIXR) and grazing incidence x-ray diffractometry (GIXRD) is a very useful method to analyze thin films in a range of 150 nm. Thin aluminium layers (30-50 nm) on Si, produced by thermal evaporation, were treated in a 2.45 GHz microwave (SLAN) discharge in three different plasma types (Ar, Ar/O-2, O-2) at low temperatures (up to 350 degrees C) to form a thin oxide additional to the native alumina on the top. The properties of the oxide layers like thickness, roughness and density were studied by GIXR, the chemical composition was investigated by GIXRD and XPS. In addition AFM was used for surface topography observations and for the evaluation of the surface modification. All these methods were applied before and after the plasma oxidation. It was found that the plasma treatment leads to an increase of the oxide layer on the aluminium film. Furthermore plasma performs a polishing effect onto the coatings, but the strength of this effect differs in dependence on the type of plasma.