AlN-based film bulk acoustic resonator devices with W/SiO2 multilayers reflector for rf bandpass filter application

Abstract

In this article, a reactively sputtered aluminum nitride (AlN) piezoelectric film and its application for a film bulk acoustic resonator (FBAR) device are presented. The FBAR is composed of an AlN film sandwiched between top aluminum (Al) and bottom gold (Au) electrodes and an acoustic reflector block of SiO2/W stacked multilayers. Both the top and bottom electrodes are connected by a transmission line. The insertion loss (S21) and return loss (S11) were 6.1 and 37.19 dB, respectively. Using the empirical definition technique, the series resonance frequency (fs) and parallel resonance frequency (fp) were found to be 1.976 and 2.005 GHz, respectively. Based on these findings, the effective electromechanical coupling coefficient (Keff2) and the quality factor (Q) were also obtained as 3.53% and 4261, respectively.