BULK ACOUSTIC RESONATOR STRUCTURES COMPRISING A SINGLE MATERIAL ACOUSTIC COUPLING LAYER COMPRISING INHOMOGENEOUS ACOUSTIC PROPERTY

摘要

In accordance with a representative embodiment, a BAW resonator structure comprises: a first BAW resonator comprising a first lower electrode, a first upper electrode and a first piezoelectric layer disposed between the first lower electrode and the first upper electrode; and a second BAW resonator comprising a second lower electrode, a second upper electrode and a second piezoelectric layer disposed between the second lower electrode and the second upper electrode. The BAW resonator structure also comprises a single-material acoustic coupling layer disposed between the first and second BAW resonators. The single-material acoustic coupling layer comprises an inhomogeneous acoustic property across a thickness of the single-material acoustic coupling layer.