Influence of sputtering conditions on microstructure and mechanical properties of Zr–Si–N films prepared by radio-frequency-reactive sputtering

Abstract

ZrN and ZrSiN films were prepared in an rf-sputtering apparatus which has a pair of targets facing each other (referred to as the facing target-type rf sputtering). In order to investigate the influence of substrate temperature on the structure and mechanical properties of Zr–Si–N films, the substrate temperature during the deposition was changed from 373 K to 673 K. Only one phase with a cubic B1 NaCl structure, typical for ZrN, can be clearly identified in all Zr–Si–N films in this study. Increasing substrate temperature can improve crystalline quality in all Zr–Si–N films in this study. Grain sizes of all Zr–Si–N thin films, despite the Si content, increase linearly with increasing substrate temperature. However, the grain growth speed with increasing substrate temperature in a pure ZrN thin film is much faster than that in Zr–Si–N thin films, because Si atom occupation of interstitial sites tends to lock diffusion paths and thus stabilize the structure. The hardness of Zr–Si–N films with low Si content, such as 3 at. % Si, decreases after the substrate temperature increases above 600 K because the internal stress drops. In the high Si content Zr–Si–N films, the hardness improved by increasing substrate temperature due to the increased strength in the grain boundaries.