Reactive sputtering of AlScN thin Ulms with variable Sc content on 200 mm wafers

Sc-doped AlN polycrystalline films are attractive active layers for high frequency (GHz range) acoustic resonators owing to the significant enlargement of the AlN piezoelectric activity with the increasing Sc content. To sputter homogenously doped AlScN films on 200 mm Si wafers we use a configurable cathode containing a variable number of embedded Sc pellets to fine tuning the Sc content in the films. The method was implemented in an Endeavor-AT™ cluster tool from OEM Group, adapted for sputtering on 200 mm wafers. 1 μm thick AlScN films with uniform Sc content (around 7 at.%), high crystal quality and good piezoelectric response have been sputtered over 200 mm production-level wafers.