SIMS Analysis of Thin Surface Layers

The characteristics of thin layers do not only depend on the chemical composition of the layer, but also on the distribution of the elements contained in the layers. On the one hand inhomogeneous distribution or inclusion of contaminations may lead to a loss of quality, on the other hand in some applications trace elements may improve the behavior or lead to novel material properties and are thus added intentionally. Because of its high detection strength (all elements can be detected within ppm range, even hydrogen) Secondary Ion Mass Spectroscopy (SIMS) is a very good technique to verify the influence of trace elements. Imaging SIMS can detect contaminations on surfaces with a lateral resolution of 1m. Distribution effects and homogeneity of the layer can also be analyzed as SIMS can give 3 dimensional images of the sample. Our research group has already gained expertise in this field as we have dealt with the analysis of thin layers during the last 3 years. Thereby various thin layers, mainly nitridic and oxidic ones, were investigated. Additionally the SIMS measuring technique and data requisition could be improved substantially. Within this former project 36 scientific articles were published. In subsequence to this project we intend to put our focus on some novel layers that have become of scientific and commercial interest within the last years. Tungsten oxide layers are famous for their electrochromic properties. Yet their application for smart windows is still not realistic. Molybdenum sulfide layers are being investigated for tribological application. In order to improve their sensitivity to oxidation in moisture different alloying elements are being tested. Furthermore the adhesion of different nitride layers, especially various titanium nitride layers, is investigated. These layers are already applied successfully in various fields of technology. However their adhesion on steel substrates with high chromium content is still limited and has to be improved. It is intended to investigate the influence of different pretreatment steps, variations in the composition of the layer and different process parameters. Within the investigation of these layers we want to improve the SIMS measurement technique (especially for the analysis of layers, e.g. variation of the primary beam intensity) and the data analysis software (e.g. further image correction).

The main goal of the project Analysis of Thin Layers with SIMS was the development of advanced methods for the characterization of surface layer analysis with Secondary Ion Mass Spectrometry (SIMS). These new analysis methods were applied to different technological relevant topics. The results were published in 23 articles in reviewed journals. One of the most important fields of thin layer analysis is the characterization of semiconductors. During the project high energies implantations, barrier layers of TFTs, implantation damage and quantum wells were investigated. Thin nitrides layers produced by Pulsed Laser Deposition (PLD) deposited were characterized to clear up the influence of trace element distribution in these layers. Furthermore the oxidation of advanced hard coatings for cutting tools was investigated. Contributions to the understanding of the influence of intermediate layers to the wettability of metallic films on carbon substrates were archived. The analysis of corrosion layers on gold coins showed that these effects are due to silver contaminations. Further the oxidation of alumina was characterized. In the field of surface characterization sintered steel and tribologic layers were inspected.