In-plane polarization for high sensitivity ferroelectric MEMS ultrasound transducers

This paper discusses the design of advanced micromachined ferroelectric ultrasound transducers for use at 3 MHz. 16/spl times/16 arrays of resonant monomorph sensors have been constructed, with sol-gel PZT as the active ferroelectric layer deposited on insulating layers of ZrO/sub 2/ and SiO/sub 2/. A novel in-plane polarization of the PZT is used to maximize sensitivity, while trading off reduced output capacitance to match the CMOS buffer electronics. This results in about 30 dB improved sensitivity compared to conventional polarizing across the thickness of the PZT layer. An equivalent circuit model as well as Finite Element results are presented. Test results are reported including transmit response, receive sensitivity.