Properties of titanium thin films deposited by dc magnetron sputtering

Titanium (Ti) thin films were deposited by dc magnetron sputtering at conventional conditions with different cathode power (75–150 W), sputtering pressure (1.1–3.3 Pa) and base vacuum ((4–13) × 10−4 Pa). The compositional properties of the films were studied using four point probe, XPS and spectroscopic ellipsometry techniques. Additionally, the structural properties of the Ti films were obtained using XRD, SEM and AFM techniques and also derived from ellipsometry data. Deposition conditions with low cathode power (75 W) and high base pressure (13 × 10−4 Pa), independent of the other parameters, yielded significant nitridation in the films and that condition, together with high sputtering pressure (3.3 Pa), resulted in transparent Ti oxide film. The films prepared under these conditions were amorphous. Otherwise, under deposition conditions of higher cathode power and lower sputtering and base pressures, only oxidation in the films was observed. The concentration of the oxide phase decreased with an increase in the cathode power and decrease in the sputtering and base pressures. Furthermore, under these conditions the films crystallized. The crystallinity increased with increase in cathode power (100–150 W) and sputtering pressure (1.1–2 Pa) and eventually was found to be amorphous with a slight increase in the base vacuum from the lowest of 4 × 10−4 Pa. However, the morphological properties of the Ti films were least influenced by the preparation conditions. The films were uniform and void free exhibiting densely packed morphological characteristics with similar smooth surface roughness. A strong relation existed between the composition and structural properties in the films. From this dependence the optimum deposition conditions is obtained to prepare metallic and crystalline Ti films under conventional conditions.