Design and Fabrication of a Novel PZT Films Based Piezoelectric Micromachined Ultrasonic Transducers

A novel piezoelectric micromachined ultrasonic transducer (pMUT), has been designed, and successfully fabricated .A bridge type structure in flexure mode was adopted for the design of the pMUT element. The transducers comprise a 4-6 mum thick silicon layer, a 1 mum thick thermal oxide layer, and 1.1 mum thick piezoelectric PZT layer . The PZT films were deposited by a sol-gel technique. The influence of different annealing processes on the films properties had been investigated. The PZT films annealed at 650degC for half an hour in air exhibit preferred orientation in the direction of the (100) plane. The piezoelectric coefficient d₃₃ of PZT films was measured as 120 pC/N. The bridge diaphragms are much more compliant and free from the clamped stress in two side edges in vibrating diaphragms in comparison with diaphragms clamped on all four edges. The sensitivity of novel pMUT is expected to be higher.