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

摘要

A PMUT array with a high fill factor and a large Q is proposed herein. The reusable design of etching holes and their optimized arrangement were analyzed and designed to achieve a high fill factor and a high Q. The demonstrated process for the present PMUT array is compatible with the CMOS process facilitating low-cost volume manufacturing in standard semiconductor foundries. Results show that the fill factor of the PMUT array and the Q of an individual PMUT are 67% and 351, respectively, validating the superior performance of the novel transducer design. Compared with those of previously published PMUT arrays,(13,21-23) the fill factor of the PMUT array proposed in this paper is improved by about 20-168%, and the PMUT array proposed features both the very small PMUT size and very small pitch between PMUTs. Furthermore, the proposed PMUT array generally exhibits a Q larger than those indicated in Ref. 13 (Q = 198) and Ref. 15 (Q = 332). More importantly, the herein proposed PMUT array features high-yield, low-costs, and volume fabrication with a simple surface micromachining process. The PMUT with a high fill factor and a large Q together with low-cost fabrication is promising for use in applications such as flow sensing, chemical detection, and energy transmission.