Characterization of ZnO-based FBAR devices for RF applications

This paper reports a two-step sputtering deposition technique for piezoelectric ZnO film formation and its successful application for film bulk acoustic resonator (FBAR) devices. The proposed two-step deposition resulted in a strongly preferred orientation toward the c-axis. Furthermore, the FBAR devices with the ZnO films showed a large return loss of 35/spl sim/50 dB at 1.5/spl sim/2 GHz. It was also found that the impedance matching of the FBAR could be easily achieved simply by controlling the resonance area of the resonator.