Low-voltage PZT-actuated MEMS switch monolithically integrated with CMOS circuit

MEMS switches actuated by PZT at low voltage were integrated with 0.35 μm CMOS. A preliminary test confirmed that the switch and the CMOS circuit worked well. PZT must be deposited at high temperature, and thus not CMOS-compatible. To overcome this limitation, we fabricated switch structures on a Si dummy wafer using PZT sol-gel method, and then transferred them to the CMOS wafer by polymer bonding. After the dummy wafer was removed, the switch structure and the CMOS circuit were connected by Au electroplating. Finally, the polymer was sacrificially etched by O₂ plasma to release the switches.