Volumenakustikresonatorstrukturen containing a single acoustic coupling material layer having an inhomogeneous acoustic characteristic

According to a representative embodiment has a BAW resonator on a first BAW resonator comprising a first lower electrode, a first upper electrode and a first piezoelectric layer which is 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 which is disposed between the second lower electrode and the second upper electrode. The BAW resonator also has a single acoustic coupling material layer disposed between the first and the second BAW resonator on. The single material acoustic coupling layer has an inhomogeneous acoustic properties over a thickness of the individual materials Acoustic coupling layer.