Bias induced structural changes in tungsten nitride films deposited by unbalanced magnetron sputtering

Tungsten nitride thin films were deposited using unbalanced magnetron sputtering system. The effect of the ratio of nitrogen partial pressure to the total pressure during deposition and the substrate bias on the tungsten nitride formation has been studied. The glow discharge characteristics of the process have been studied in order to determine the deposition parameters. It is observed that nitrogen partial pressure ratio 0.4 and cathode current of 200 mA favors the formation of the W2N films. The variation in the electrical resistivity of the films has been studied as a function of nitrogen partial pressure and substrates bias. A minimum resistivity of 406 μΩ cm is observed for tungsten nitride films prepared at −70 V bias. X-ray diffraction analysis of the films indicate the formation of β-W2N (1 0 0) phase at the partial pressure ratio of 0.4. The effects of the bias on the structural properties were also studied at this condition. The internal stress and the particle size of the deposited films were calculated and it was found that there is no appreciable change with the applied bias voltage.