Effect of process pressure on PVD AlN thin film

PVD AlN film deposition rate, within wafer stress uniformity, roughness and crystal orientation were studied on different process pressure. It was found that AlN deposition rate decreased with pressure increased. The decreasing rate dramatically increased when process pressure more than 12mT. Film stress tends to be more tensile with increased pressure at wafer edge and becomes more compressive when process pressure higher than 14mT. Within wafer film stress range can be reduced from ~600MPa to ~300Mpa when process pressure increased from 7mT to 14mT. Film becomes more rough with process pressure increased. Roughness RMS increased from 2.605~2.825nm to 3.131~3.692nm when pressure increased from 7mT to 14mT.