2D multiphysics frequency simulations of thin-film bulk acoustic wave resonator

A two dimensional (2D) finite element model of thin film bulk acoustic wave resonator (FBAR) is created in COMSOL Multiphysics to investigate the shifting of the parallel and series resonance frequencies as a function of the thickness of the electrodes. The dependence of the electromechanical coupling coefficient and quality factor from electrode thickness is also studied. A classical FBAR with aluminum nitride as piezoelectric layer and aluminum electrodes is modeled. The piezoelectric layer is chosen to resonate in the Personal Communications Service Band I (Tx: 1850.2-1909.8 MHz; Rx: 1930.2-1989.8 MHz). A methodology to build a 2D model of a FBAR in COMSOL and parameterize the electrode thickness is described.