Molecular dynamics simulations of Si, SiC and Si3N4 layered systems

Experimental and empirical work in the field of nano-scale, functional multilayer coatings produced by physical (PVD) or chemical (CVD) vapor deposition are currently an object of international research. The research results have already been implemented in industrial products, however, the atomistic understanding of the underlying processes during deposition of these multilayer systems is still incomplete. In particular the correlation between the deposition parameters and the resulting coating structure needs further attention. To overcome the heuristic stage of the coating development and to facilitate targeted and efficient optimization of the coating structure and the resulting mechanical properties, a deeper understanding of the correlation between the substrate temperature, deposition rate and energy onto the growing coating structure is necessary. The same holds for the structure-properties correlation of these systems with a large number of interfaces as well as for the mechanical properties of individual layers. The aim of this work is the combination and mutual validation of modern molecular dynamics simulations (MD) with experimental methods of physical vapor deposition of silicon and silicon-based SiC- and Si3N4-protective coatings. This was done within the framework of the research project "Molecular dynamics modeling and validation of manufacturing and structure-property correlations of SiC/SiN nano laminates" funded by the German Research Foundation (DFG) and in a collaboration between the Institute for Materials Testing, Materials Science and Strength of Materials (IMWF) at the University of Stuttgart and the Institute for Applied Materials - Applied Materials Physics (IAM-AWP) at the Karlsruhe Institute of Technology (KIT). While molecular dynamics simulations were performed at the IMWF, experimental investigations took place at the IAM-AWP. Hereby, the results of MD studies served as input parameters for experimental investigations. In this way, time-consuming and expensive experimental investigations could be avoided, since only optimistic simulation predictions had to be verified experimentally. In return, the group at the IAM-AWP delivered experimental results which were used to validate the simulation model. In general, each experimental study was also represented by a MD simulation. Hence, the entire process of the coating deposition and characterization can be divided into three distinct stages: - Simulation and experimental investigation of the sputtering process of Si, SiC and Si3N4. - Simulation und experimental investigation of the deposition process of silicon substrates by Si, SiC and Si3N4. - Simulations and experimental characterisation of the correlation between the structure and properties of the deposited silicon and silicon-based SiC- and Si3N4- protective coatings.