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D. Böhm, T. Schrefl, A. Eder, C. Eisenmenger-Sittner:
"Prediction of composition, crystalline structure and microstructure of sputtered multi-component coatings by a Virtual Machine";
Vortrag: ICMCTF 2021, San Diego/USA; 26.04.2021 - 30.04.2021.

Keywords: sputtering, co-sputtering, thin film multilayer, thin film composite material, sputter-simulation, simulated film growth, XRD diffractogram calculation, XRD measurement, microstructure prediction

To be able to predict the composition and the structural properties of multi-component thin films deposited by magnetron sputtering a so-called Virtual Machine (VM) was designed. The VM is an interactive ray tracing software that simulates film growth by a line-of-sight model, also taking into account the decay of the flux density of the particles due to gas phase scattering.
The VM is initiated with a 3D model of a real sputter system which includes the static arrangement of multiple targets and the substrate and eventual obstacles, as well as dynamics like e. g. rotating substrate holders. Then the composition, the microstructure and the crystallographic phases with their associated XRD patterns are calculated for the simulated film. On each sampling point a composition is calculated over several time steps associated with an adjustable temperature which can be different for each step enabling the correlation of the real temperature distribution during the coating experiment. Depending on the material and the applied simulation parameters e.g temperature or coating rate models of grain growth and island formation are applied.
With this information and a library of binary phase diagrams the corresponding crystallographic phase can be calculated and displayed per time step. The XRD patterns are calculated from the crystallographic phases and summed over all time steps. This procedure allows to construct a diffractogram which can be compared to the diffractogram of an accordingly produced sample. Another way to display the data is to stack the appearing composition and phases over all time steps. Such a phase stack is equivalent to an EDX line scan performed on a metallurgical cross section from the substrate to the surface of the coating. Several phase stacks can be compared with an element mapping of the cross section. Since surfaces and volume diffusion are not yet considered, only immiscible multilayer systems can be investigated at present. On the basis of examples the above mentioned comparisons are presented.

Acknowledgments
This project has received funding from the Clean Sky 2 Joint Undertaking under the European Union´s Horizon 2020 research and innovation program under Grant No 785414