Structural and electrical characteristics of W-N thin films prepared by reactive rf sputtering

The dependence of the electrical and structural characteristics of sputtered W-N films on the substrate bias, N₂ partial flow rate, and sputtering was examined. Enhancement of ion bombardment by applying a negative bias on the substrate does not change the crystal structure and bonding state of the W-N films. However, resistivity of W-N films was reduced by increasing the substrate bias. Using 150 W of sputtering power, GIAXRD and XPS analyses indicate that sputtered W-N films will transform from metallic W to amorphous-like WN films with increasing N₂ flow ratio. Consequently, resistivity of W-N films increased while the deposition rate decreased with increasing N₂ partial flow rate. Compositional analysis revealed that W:N ratio in the crystalline W₂N film sputtered at 150 W is overstoichiometric in nitrogen.