Investigation of an ion-milled Si/Cr multilayer using micro-RBS, ellipsometry and AES depth profiling techniques

To investigate the details of the ion beam induced mixing and validate the Auger electron spectroscopy depth profiling technique, sputter-deposited Si 40 nm/Cr 40 nm multilayer samples were irradiated with a 20 keV CF4+ ion beam. Due to the ion bombardment the top Si layer was damaged and a crater was created. Elemental depth profiles and layer thicknesses together with surface topography were measured with Rutherford backscattering spectrometry by applying a focussed 2 MeV He+ beam. The thickness of the top Si layer was also determined from ellipsometry measurements. The results are compared to that of obtained from Auger electron spectroscopy depth profiling.