GHZ higher order contour mode ALN annular resonators

Abstract

This work introduces a new class of low motional resistance piezoelectric aluminum nitride (AlN) MEMS ring resonators that operate in GHz contour modes of vibration. The resonators are based on an annular thin film AlN structural layer sandwiched between two or more pairs of concentric transduction electrodes whose design effectively uncouples the resonant frequency of the device from its transduction area (and consequently its motional resistance) at the layout level. The devices under test exhibit lithographically-defined fundamental series resonant frequencies from 1.03 to 1.60 GHz, motional resistances from 57 to 130 Omega, a resonator figure of merit (FOM = kt 2Q) of 6.4 to 7.4, and no coherent spurious responses from DC to 5 GHz.