Micromachined thick film piezoelectric ultrasonic transducer array

The paper presents two-dimensional membrane-type ultrasonic transducer arrays based on thick piezoelectric films and micromachining. The transducer array can be used to generate ultrasound in air or water. An individual array element consists of a thick piezoelectric film and a periphery clamped rectangular membrane. The vibrating membranes, which are the radiating elements of the transducer, are excited by the thick piezoelectric film. A composite coating technique, based on chemical solution deposition and high-energy ball milled powders, has been employed to fabricate a thick PZT film on a platinized silicon wafer. High yield micromachining of the integrated transducer array on a silicon or SOI wafer using thick PZT films, with thickness up to 10 μm, has been successfully demonstrated. The directivities of the array have also been measured and are reported.