Active area optimisation of film bulk acoustic resonator for improving performance parameters

Abstract

In this Letter, an active area optimisation technique to improve the performance parameters of the film bulk acoustic resonator (FBAR) is proposed. The active area of the back trench membrane‐based FBAR is optimised to remove the spurious modes, higher harmonic modes, and to confine the acoustic signal at its central part during the resonance. The effect of thickness variation of SiO 2 layer on the performance parameters was studied using finite‐element analysis (FEA) simulation. The SiO 2 film, on silicon substrate, was used as the support layer and zinc oxide was used as the piezoelectric film for the resonator. The authors have successfully demonstrated the FBAR through FEA for an optimised active area of 320 × 320 µm 2 , series resonance frequency ( f s ) 1.249 GHz, and parallel resonance frequency ( f p ) 1.273 GHz with an effective electromechanical coupling coefficient of 4.65%.