AES, XPS AND TEM CHARACTERIZATION OF METAL-OXIDE MULTILAYERS

Multilayer structures for application in microelectronics, hard and wear resistant as well as optical coatings are becoming increasingly complex. Therefore, there is a permanent need for new model multilayer structures appropriate for high resolution depth profiling studies which are helpful for the interpretation of everyday analytical results. A new type of metal/oxide multilayer structure composed of alternating Cr, Ni, NiO and Cr2O3 layers with a total thickness of about 475 nm was sputter deposited onto a smooth silicon substrate. By TEM investigations we found a columnar crystalline structure of Ni, Cr and NiO layers with a comparable size of crystal grains while the Cr2O3 layer showed a partial amorphous structure with a small amount of a crystalline phase. Compositional depth profiles of the model multilayer structure were obtained with Auger and X-ray photoelectron spectroscopy on stationary and rotated samples. The AES and XPS depth profiles are discussed with respect to different instrumental parameters and the influence of crystalline and amorphous structures on depth resolution. The AES depth profiling of stationary samples, using a unidirectional ion beam, shows an evident beneficial influence of the oxide sandwich layers on depth resolution.