Optimal target sputtering mode for aluminum nitride thin film deposition by high power pulsed magnetron sputtering

Abstract

Low surface roughness, low residual stress, and (002) textured aluminum nitride (AlN) thin films are favored for applications in microelectronic and optoelectronic devices. In this paper, AlN thin films were deposited by reactive high power pulsed magnetron sputtering (HPPMS). The effect of aluminum target sputtering mode and sputtering power on thin film residual stress, crystalline structure, surface roughness, and morphology of AlN thin films was studied. The results indicate that, with Al target sputtering mode transfer from metallic mode to transitional and compound modes, respectively, the number of Al species decrease, and ion-to-neutral ratio of Al species increase. Comparing the AlN thin film deposited in compound mode with that deposited in transitional mode, the latter exhibited lower surface roughness and residual stress. In addition, AlN thin film with (002) texture and lower residual stress is obtained by increasing sputtering power in transitional mode. For fabricating AlN film via reactive HPPMS with a particular (002) texture, low surface roughness, and residual stress, sputtering the target in the transitional mode with high sputtering power is optimal.