Design and Fabrication of a High Frequency Thin Film Resonator Using Low Acoustic Impedance Reflective Layer

A high frequency thin film resonator using single reflective layer is presented. The reflective layer is chosen to have a low acoustic impedance to reflect acoustic waves, which is generated by the piezoelectric layer above it. With an air interface serves as a free boundary at the other end of piezoelectric layer, a high frequency resonator can be formed. Since the fabrication process included no bulk etching and multi-layer, a high manufacturability can be achieved. Moreover, the novel device and its applications can be designed to be suit many mobile communication applications.