Aluminum nitride (AIN) film is an excellent piezoelectric material in 5G high- frequency SAW & BAW filters and MEMS sensors. In particular, the scandium doped Aluminum notride (ScAIN) film can greatly improve its piezoelectric coefficient, thereby improving the electrocmechanical coupling coefficient of SAW & BAW. It is the core piezolelectic material of a new generation of 5G RF filters. ScAIN thin films are usually obtained by reactive sputtering of AL-Sc alloy targets.