Patent ID: 10574210

Abstract:
The present disclosure relates to a Wafer-level-packaged Bulk Acoustic Wave (BAW) device, which includes a bottom electrode, a top electrode, a top electrode lead, a piezoelectric layer sandwiched between the bottom and the top electrodes, an enclosure, and an anti-reflective layer (ARL). Herein, an active region for a resonator is formed where the bottom electrode and the top electrode overlap. The top electrode lead is over the piezoelectric layer and extending from the top electrode. The enclosure includes a cap and an outer wall that extends from the cap toward the piezoelectric layer to form a cavity. The top electrode resides in the cavity and a first portion of the outer wall resides over the top electrode lead. The ARL, with a reflectance less than 40% R, is between the first portion of the outer wall and the top electrode lead.