Piezoelectric micromachined ultrasonic transducer and method of fabricating the same

Abstract

A PMUT includes a substrate, a membrane, and a sacrificial layer. The substrate has a cavity penetrating the substrate. The membrane is disposed over the cavity and includes a first piezoelectric layer, a bottom electrode, a top electrode, and a second piezoelectric layer. The first piezoelectric layer is disposed over the cavity and includes an anchor portion, where the anchor portion of the first piezoelectric layer is in direct contact with the substrate. The top and bottom electrodes are disposed over the first piezoelectric layer. The second piezoelectric layer is disposed between the bottom electrode and the top electrode. The sacrificial layer is disposed between the substrate and the first piezoelectric layer, and a vertical projection of the sacrificial layer does not overlap a vertical projection of portions of the membrane disposed over the cavity.

Dependencies are inferred from the claim text.