Microstructure and mechanical properties of sputtered Aluminum thin films

The microstructure, surface roughness and mechanical properties of aluminum thin films deposited by rf magnetron sputtering are presented. The films were sputtered on stainless steel substrates at varying rf powers of 150 W, 200 W, 300 W and 350 W at a deposition time of 2 hours and at a substrate temperature of 90^oC. The microstructure at 200 W shows fine, well-defined and homogeneous distributed grains. The lowest surface roughness is at the power of 150 W whereas the highest is at 250 W. The highest modulus, hardness and lowest depth of penetration are obtained at 200 W. The results indicate no direct relationship among rf power, mechanical, roughness and microstructure of Al thin films deposited at substrate temperature of 90^oC. As such, optimization of the sputtering process for rf power is necessary for deposition of quality Al films on metals.