Development of piezoelectric micromachined ultrasonic transducer with dual heterogeneous piezoelectric thin film stacking

In this study, we prototyped a piezoelectric micromachined ultrasonic transducer (pMUT) with dual heterogeneous piezoelectric thin films stacked on top of each other. Whereas one piezoelectric thin film features a high actuation performance, the other presents a high reception performance. The suitable material is used depending on whether the ultrasound is transmitted or received. At first, simulation was performed to demonstrate that the figure-of-merit (FOM) performance of the AlN/Pb(Mg
1/3
, Nb
2/3
)O
3
-PbTiO
3
(PMN-PT) stacked pMUT and Pb(Zr, Ti)O
3
(PZT)/AlN stacked pMUT was 2.8 and 2.3 times higher than the conventional pMUT, respectively. Next, the two types of dual-layer pMUTs mentioned earlier were successfully fabricated taking into account process compatibilities. Finally, the motions of the dual-layer pMUTs were characterized.