Qualification and applications of a piezoelectric MEMS process

An industrializable process for manufacturing of piezoelectric ultrasound transducer elements is demonstrated. The PZT film is deposited by chemical solution deposition on SOI wafers, and standard MEMS processes are utilized to make cantilevers, bridges and membranes. The PZT film of ~50% of the devices exposed to thermal aging were found to fail at 85°C – 85%RH (relative humidity), while a real-life test of 8·1010 cycles at resonance only gives a slight change in Q-value and resonance frequency.