GaN-on-Si mm-wave RF Devices Integrated in a 200mm CMOS Compatible 3-Level Cu BEOL

We report on the development of mm-wave GaN-on-Si AlGaN HEMTs integrated with a 3 level Cu damascene BEOL flow on 200mm Si <111> wafers. Optimizations of the gate metal stack, contact resistance and gate length scaling to 110nm result in devices with a peak g
m
of 430 mS/mm and an f
MAX
of 135 GHz. While wafer warp was found to increase slightly through the processing of 3 levels of 1µm thick Cu metal, no significant deterioration was observed between devices measured at Metal 1 and Metal 3.