K. Thorwarth; M. Watroba; O. Pshyk; S. Zhuk; J. Patidar; J. Schwiedrzik; J. Sommerhäuser; L. Sommerhäuser; S. Siol
Surface & Coatings Technology 512 (2025) 132326
Ternary transition metal nitride coatings are promising for many applications as they can offer improved
hardness and oxidation resistance compared to their binary counterparts. A common challenge in the deposition
of functional nitride thin films is oxygen contamination. Even low amounts of oxygen contamination can
adversely affect the functional properties of the thin films, especially hardness and electrical properties. Here, we
present a practical approach for the growth of virtually oxygen-free (Ti, Zr)N thin films.
To cover the complete compositional range of (Ti, Zr)N coatings we employ combinatorial reactive co-
sputtering. The compositional gradients are complemented by orthogonal deposition temperature gradients to
cover broad regions of the synthesis phase diagram. The depositions are carried out with or without applying a
low-power radio-frequency (RF) bias voltage to the substrate holder to study the possibility of decelerating
energetic oxygen ions and effectively reducing oxygen contamination in the growing film. High-throughput
structural analysis and functional property mapping are used to elucidate the synthesis-property relationships
in large regions of the synthesis phase diagram. The structural analysis indicates solid-solution formation over
the entire compositional range, as evidenced by Vegardian lattice scaling, regardless of the applied RF substrate
bias. Irrespective of the composition of the films, the application of RF substrate bias leads to a dramatic
reduction of oxygen contamination, as demonstrated by X-ray photoelectron spectroscopy (XPS) depth-profile
mapping. This is reflected in a significant improvement in the films’ conductivity as well as hardness. We
demonstrate that the reduction in oxygen contamination is intrinsic to the process as well as due to changes in
the microstructure, which also leads to varying oxidation resistance in ambient conditions. The approach pre
sented here is applicable to both conductive and insulating substrates and provides a practical route to synthesize
nitride thin films with improved purity that can be applied in standard sputter chambers and on many different
material systems.