Wlp baw device with through-wlp vias

An apparatus comprising:

• a piezoelectric layer with a first interface opening;
• a bottom electrode over a bottom surface of the piezoelectric layer;
• a bottom electrode lead over the bottom surface of the piezoelectric layer and extending from the bottom electrode, wherein a portion of the bottom electrode lead is exposed through the first interface opening of the piezoelectric layer;
• a first interface structure extending over the first interface opening and in contact with the exposed portion of the bottom electrode lead;
• a top electrode over a top surface of the piezoelectric layer, wherein:
• the top surface of the piezoelectric layer is opposite the bottom surface of the piezoelectric layer;
• and
• an active region for a resonator is formed where the bottom electrode and the top electrode overlap;
• and
• a Wafer-Level-Packaged (WLP) enclosure comprising a WLP cap, an outer wall, and a first through-WLP via, wherein:
• the outer wall extends from the WLP cap toward the top surface of the piezoelectric layer to form a cavity, and the top electrode resides in the cavity;
• the first through-WLP via extends vertically through the WLP cap and the outer wall, and is encompassed by the outer wall;
• and
• the first through-WLP via of the WLP enclosure is vertically aligned with the first interface opening of the piezoelectric layer, and a portion of the first interface structure is exposed to the first through-WLP via;
• and
• a first interconnect formed in the first through-WLP via and electrically connected to the first interface structure.