One-dimensional linear acoustic bandgap structures for performance enhancement of AlN-on-Silicon micromechanical resonators

This work introduces piezo-on-silicon linear acoustic bandgap (LAB) structures, a class of compact 1D micro-scale phononic crystal (PC) which can be directly integrated with micromechanical devices. Finite element simulations with custom-derived dispersion equations predict multiple bandgaps for coupled-ring LAB structures into the GHz region. AlN-on-Si resonator are replaced with coupled-ring LAB tethers to reduce acoustic loss into the substrate; the existence of bandgaps is experimentally confirmed in transmission spectra of test structures as well as quality factor (Q) and insertion loss (IL) improvements of LAB-enhanced resonators. An IL of 3.8 dB at 178 MHz and Qs of greater than 11,000 at 600 MHz in air are reported.