LiNbO3 Film Bulk Acoustic Resonator

Abstract

As layer transfer techniques have been notably improved these passed years, lithium niobate (LiNbO3) appears as a candidate for the next generation of ultra wide band Radio Frequency (RF) filters. Depending on the crystalline orientation, LiNbO3 can achieve electromechanical coupling factors Kt2 more than 6 times larger than those of sputtered aluminium nitride films. In this paper, a process based on direct bonding, grinding, polishing and Deep Reactive Ion Etching (DRIE) is proposed to fabricate a single crystal LiNbO3 Film Bulk Acoustic Resonator (FBAR). From the fabricated test vehicles Kt2 of 45% is measured confirming the values predicted by theoretical computations.