Wafer level fabrication of high performance MEMS using bonded and thinned bulk piezoelectric substrates

We report a batch-mode fabrication technology for integration of bulk piezoelectric materials into MEMS devices, and test results of high-performance out-of-plane piezoelectric actuators fabricated with this technology. Low-temperature (200degC), reliable AuIn and Parylene bonding of PZT wafers/dies on Si wafers is achieved, and lapping is used to obtain <10 mum PZT films. Conservation of the piezoelectric properties is confirmed with a hysteresis measurement. Additionally, square and circular shaped PZT diaphragms with 4 mm times 4 mm, 2 mm times 2 mm, and 1 mm times 1 mm sizes operating in the d31-mode are fabricated with a 2-mask fabrication process. Greater than 12 mum peak-to-peak deflection is obtained by actuation of a 1 mm² diaphragm at resonance (110.9 kHz) with a power consumption of <7 mW.