Micromachined thick film piezoelectric ultrasonic transducer array

This paper presents two-dimensional membrane-type ultrasonic transducer arrays based on thick piezoelectric film and micromachining. The transducer array can be used to generate ultrasound in air or water. 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 thick piezoelectric film. A composite coating technique based on chemical solution deposition and high-energy ball milled powders has been employed to fabricate thick PZT film on platinum coated silicon wafer. High yield micromachining of the integrated transducer array on silicon or SOI wafer using such thick PZT films with thickness of up to 10 μm has been successfully demonstrated. The directivities of the array have also been measured and reported.