Comparative investigation of the structure and mechanical properties of AlCrN and AlCrVYN thin films deposited by dcMS, HiPIMS, and hybrid dcMS/HiPIMS

Abstract

AlCrN and AlCrVYN thin films were deposited by physical vapor deposition using dcMS, HiPIMS and hybrid dcMS/HiPIMS processes. Although all the thin films were produced using the same time-average power and show only slight differences in the chemical composition, significant differences regarding their structure, morphology, and mechanical properties were identified. Both dcMS-AlCrN and dcMS-AlCrVYN thin films show a column-like structure of sharply defined grains with large crystallites having size of 168 nm and 133 nm and exhibit a low hardness of (6.7 ± 1.3) GPa and (8.9 ± 1.0) GPa, respectively. In contrast, HiPIMS thin films, despite their lower deposition rate (especially evident in HiPIMS-AlCrVYN, which exhibited the lowest deposition rate among all examined films), show a denser structure predominantly composed of fcc-CrN and, in the case of HiPIMS- and dcMS/HiPIMS-AlCrN, small amounts of hcp-AlN. Consequently, the HiPIMS-AlCrN and HiPIMS-AlCrVYN thin films showed higher hardness values of 28.0 ± 2.1 GPa and 30.7 ± 1.9 GPa, respectively. Combining the two methods by using one cathode in dcMS mode and one in HiPIMS mode results in films with similar hardness values (26.9 ± 1.6 GPa for AlCrN and 28.7 ± 2.2 GPa for AlCrVYN) and morphologies comparable to the pure HiPIMS thin films, but with an increase in the deposition rate. This demonstrates the advantage of combining the two methods, especially for the AlCrVYN thin film production. In comparison to AlCrN, the AlCrVYN thin films generally exhibit higher hardness demonstrating the advantage of adding larger atoms into the thin film structure.