Tailoring of titanium thin film properties in high power pulsed magnetron sputtering

Ti films are widely used in electrical engineering, biomedical instrumentation, and other industries owing to their excellent material properties. High Power Pulsed Magnetron Sputtering (HPPMS) is a promising physical vapor deposition (PVD) technique used for producing highly ionized target species, thereby opening the possibility of controlling the material properties of the growing films. Controlling the thin film properties helps achieve high quality films to cater the needs of a specific application. In this study, Ti films properties were tailored by controlling the peak and average target power values in HPPMS. The effect of peak and average target power on the plasma composition above the substrate was systematically studied. For a constant average power, the increase in the peak power significantly raises the ion-to-atom ratio and density of the plasma flux incident on the substrate. This leads to the Ti films exhibiting compressive stress, smaller grain size, and smoother surface at lower deposition rates. On the other hand, the increase in the average power at a constant peak power causes no remarkable change in the ion-to-atom ratio, but the overall magnitude of the number of metal ions and atoms and gas temperature around the substrate increase obviously. The Ti films deposited at high average powers were characterized by larger grain size with a highly preferred orientation of (002), rougher surface, and exhibited signs of tensile stress. The results obtained from this study provide guidelines for achieving high quality hard metal films with desired properties by manipulating the peak and average power in HPPMS discharge.