Application of Film Bulk Acoustic Wave Resonator for Sensitive Mass Sensor

Abstract

Film Bulk Acoustic wave Resonator (FBAR) is one of the band pass filters employed for high frequency devices. In order to apply FBARs to sensitive mass sensor, quality factor defined by the ratio of the resonance frequency to the full width at half maximum for the frequency characteristics is required to be large. In this study, operating characteristic for the FBAR was analyzed using the commercialized software Ansys (Ansys Inc.) which solves electric field-structure coupled problems using a 3 dimensional finite element method. A change in resonance frequency for the FBAR due to additional weight was confirmed by the simulation, and the FBAR was estimated to show the 10 Hz of the change in the resonance frequency for 2 GHz band operation when 2 pg of additional weight was loaded. Thereby the FBAR was considered to work as a sensitive mass sensor. The electrode materials were found to affect quality factor, and the highest quality factor was also found to be obtained when the electrode is TiN compared with Mo, Ru, Rh and W.