Design of high-Q Thin Film Bulk Acoustic resonator using dual-mode reflection

In this paper, the Q-factor enhancement of the Thin Film Bulk Acoustic Wave Resonator (FBAR) with Type-II dispersion is investigated. Our purpose is to improve the Q-factors of the resonator, especially the one at anti-resonance frequency (f_a), by the application of a frame structure on its periphery. The frame performs as a lateral acoustic Bragg reflector, which is able to reflect two Lamb modes S₁ and S₀ upon the FBAR border region. These two modes are presumed to contribute the most to lateral acoustic leakage. The results of one of the modified FBARs exhibit a superior improvement of the Q factor at f_a (Q_a) of about 1000 over the one without optimization.