High Fill Factor Array of Piezoelectric Micromachined Ultrasonic Transducers with Large Quality Factor

Ding Jiao, Zao Ni, Jiachou Wang, Xinxin Li
2020 Sensors and materials  
In this paper, we present a novel piezoelectric micromachined ultrasonic transducer (PMUT) array with a high fill factor and a large quality factor (Q). With the reusable design of etching holes, the pitch between PMUTs is effectively minimized, improving the fill factor of the array. With a newly developed surface micromachining process, the fabricated PMUT array only needs few etching holes to release the structure, and all sealed etching holes are removed from the resonance region, achieving
more » ... a large Q. The demonstrated process facilitates low-cost volume manufacturing. As a result, a 50 × 50 PMUT array containing 48-μm-diameter PMUTs with a 52 μm pitch achieves a high fill factor of 67%. For an individual PMUT, a large Q of 351 is achieved at a center frequency of 12.62 MHz, the peak displacement is 3.25 nm/V, and the effective electromechanical coupling coefficient is 1.6%. The achieved high fill factor and large Q render the proposed PMUT array promising in applications such as flow sensing, chemical detection, and energy transmission.
doi:10.18494/sam.2020.2749 fatcat:mwcv7o7r4ragvld3nxgllqg2py