The influence of deposition parameters on the structure and properties of aluminum nitride coatings deposited by high power impulse magnetron sputtering

In this work, aluminum nitride (AlN) thin films were fabricated using the high power impulse magnetron sputtering (HIPIMS) process through the Taguchi method to determine the optimum deposition condition. A L9 array, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) were applied to study the deposition parameters (pulse frequency, duty cycle, temperature, and substrate bias)with consideration of the microstructure, hardness and transmittance properties of AlN coatings. The wurtzite hexagonal AlN structure was achieved for each coating. Typical fine and dense columnar structure was observed for AlN coating. Based on the higher the better concept using S/N ratio and the contribution using ANOVA, the substrate bias was the most influential parameter for the hardness of AlN coating. On the other hand, the duty cycle was important proportionally for the transmittance of AlN coatings. Confirmation tests with optimal deposition parameters were performed to verify the effectiveness of the Taguchi optimization analysis in this work. The maximum hardness of 25 GPa and transmittance of 83.4% were achieved, respectively, for the AlN coatings deposited with optimal deposition parameters.