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L. Zauner, T. Wojcik, T Kozák, J Capek, H. Bolvardi, S. Kolozsvári, P.H. Mayrhofer, H. Riedl:
"Reactive HiPIMS deposition of Ti-Al-N: Influence of the deposition parameters on the cubic to hexagonal phase transition";
Talk: 17th International Conference on Plasma Surface Engineering, Erfurt, Deutschland; 2020-09-07 - 2020-09-10.

The introduction of enhanced ionization rates during reactive high-power impulse magnetron sputtering (R-HiPIMS) allows for additional pathways in tuning the structural and chemical evolution by surface-diffusion driven growth. Hence, especially depending upon the charge state and mass-ratio of the metal-ions incident on the growing film, metastable thin films are decisively influenced in their overall growth characteristics.
Here, we review in detail the dependence of the phase-stability (i.e. xmax) on varying deposition parameters during R-HiPIMS of Ti-Al-N thin films using Ti1-xAlx composite targets. The influence of HiPIMS pulse parameters such as frequency, pulse length, or peak power density, but also of deposition parameters including N2 partial pressure, substrate bias voltage, or target compositions were investigated methodically. The so obtained coating structures were analysed with respect to phase-stability, thermo-mechanical properties, and morphology applying nanoindentation, X-ray diffraction combined with electron imaging techniques. The systematic studies revealed an Al solubility limit of xmax~0.55, obtained for a duty cycle of 3.75 % and a N2-to-Ar flow-rate ratio of 0.3. Moreover, sufficient intermixing of the arriving film species controlled via bias potentials was observed as decisive for the deposition of high Al containing fcc-structured coatings. Based on time- and energy resolved mass-spectroscopy measurements it can be concluded that the ratio and energy of Tin+- and Aln+-ions, arriving simultaneously at the substrate surface, are highly influential for stabilising the preferred cubic modification with respect to the prevailing deposition conditions.

R-HiPIMS; Ti-Al-N; Phase Formation; Deposition Parameters; Mass-spectroscopy;

Project Head Helmut Riedl:
CDL-SEC