Industrial validation of the PMUT ultrasonic flowmeter based on CSOI

This paper demonstrates the industrial validation of the piezoelectric micromachined ultrasonic flowmeter based on cavity silicon-on-Insulator(CSOI). The piezoelectric micromachined ultrasonic transducers(PMUTs) array was fabricated on an 8-inch CSOI wafer with unique structural layers and high scandium concentration.Through controlling the wafer-level stress variation at ±80 MPa and patterning the device layer,the great electrical characterization showed great wafer-level uniformity and yield. This implies that the device can be utilized in batch production. The reliability test conducted on PMUTs array (2.8 mm × 2.8 mm) revealed that the zero-flow offset of arbitrarily selected sensors is only 3ns and the receiving amplitude variation with temperature is within 25% witch much less than bulks.These results have a positive impact on promoting the industrialization of PMUTs.