Aluminium and silicon determination on two Si-Al sputter targets used for magnetron sputtering

Si–Al coatings of different stoichiometry can be produced by unbalanced magnetron sputtering. The Si–Al alloy target used for this technique are prepared by two different ways:

• Silicon and aluminium are reduced to powder and pressed together in order to obtain a homogeneous target containing a known amount of aluminium and silicon.
• Si–Al alloy is produced by Péchiney (Voreppe, France) and contains small silicon grains impregnated into a Si–Al alloy.

Aluminium and silicon concentrations of such alloys were measured by Proton Induce X-ray Emission (PIXE) using the microprobe facility at LARN (Namur, Belgium). Measurements were carried out in the tracks due to material removed by sputtering when the target is used for DC-magnetron and also in the virgin zone where no material has been removed.

The results show clearly that the relative concentrations of Al and Si are not preserved when the target is sputtered with 500 eV Ar atoms. This result can be explained by the different sputtering yields of Al and Si and the stoichiometry of the coatings are related to the composition of the target.