Effect of DC input power and nitrogen ratio on the deposition of Ti1 − xAlxN thin films using high power impulse magnetron sputtering technique

• Ti1 − xAlxN thin films were deposited using a high power impulse magnetron sputtering (HiPIMS) method.
• The current-voltage characteristics of the Ti30Al70 target was investigated.
• N/(Al + Ti) ratio, ranging from 0.57 to 1.28, and the x value of Ti1 − xAlxN, ranging from 0.72 to 0.86 were obtained.
• The dual phases of cubic-Ti1 − xAlxN and wurtzite-AlN co-exist in the resulting films.
• The hardness exhibits a strong dependence to the N/(Al + Ti) ratio.

Ti1 − xAlxN thin films with x varying from 0.72 to 0.86 were deposited using a high power impulse magnetron sputtering (HiPIMS) method in this research. The current-voltage characteristics of the Ti30Al70 target was first investigated to determine the HiPIMS parameters for film deposition. The microstructure and hardness of the resulting films grown under different target powers and different N2/Ar flux ratios have been studied. It was found that the dual phases of cubic-Ti1 − xAlxN and wurtzite-AlN co-exist in the resulting films while the grain sizes of wurtzite-AlN are all smaller than that of the cubic-Ti1 − xAlxN. The deposition rate, ranging from 4 to 9 nm/min, decreases with increasing N2/Ar flux ratio or decreasing target power. N/(Al + Ti) ratio, varying between 0.5 and 1.3, was found to increase with increasing N2/Ar ratio. Films having the highest hardness of 22.3 GPa was obtained when the duty cycle was 3%, the power was 1.8 kW, and the N2/Ar flux ratio was 0.46. The hardness exhibits a strong dependence to the N/(Al + Ti) ratio.