Abstract: A bulk acoustic wave (BAW) device includes a substrate, a reflector on the substrate, a piezoelectric layer on the reflector and including a first opening through which a portion of the reflector is exposed, an electrode layer on the portion of the reflector exposed through the first opening, a passivation layer on the piezoelectric layer and a portion of the electrode layer and including a second opening through which a portion of the electrode layer is exposed, an under-bump metallization layer on the portion of the electrode layer exposed through the second opening and extending over the second opening and the first opening on the passivation layer, and a copper pillar structure on the under-bump metallization layer such that the entirety of the under-bump metallization layer is covered by the copper pillar structure.

Abstract: A bulk acoustic wave (BAW) device includes a substrate, a reflector on the substrate, a piezoelectric layer on the reflector and including a first opening through which a portion of the reflector is exposed, an electrode layer on the portion of the reflector exposed through the first opening, a passivation layer on the piezoelectric layer and a portion of the electrode layer and including a second opening through which a portion of the electrode layer is exposed, an under-bump metallization layer on the portion of the electrode layer exposed through the second opening and extending over the second opening and the first opening on the passivation layer, and a copper pillar structure on the under-bump metallization layer such that the entirety of the under-bump metallization layer is covered by the copper pillar structure.

Abstract: A wafer level package (WLP) device includes a wafer level core and a cap structure. At least one component is formed in or on the wafer level core, and the cap structure resides on the top surface of the wafer level core and forms a cavity over the component. The cap structure includes a perimeter wall that rests on the top surface of the wafer level core and extends about the component. The perimeter wall has a top surface divided into a covered portion that extends along an inner portion and an uncovered portion that extends along an outer portion. The lid has a bottom surface, wherein an outer periphery of the bottom surface of the lid rests on and only covers the covered portion of the top surface of the perimeter wall.