Design of AlN Meshed LCAT Mode Resonators for Coupling Coefficient Beyond BAW

This work presents a novel resonator structure with meshed-shape aluminum nitride (AlN) body The resonator adopts the concept of laterally coupled alternating thickness (LCAT) mode which closely couple the lateral and thickness resonant modes to improve the effective coupling coefficient (k2eff). The k2eff is further boosted by removing the redundant resonator body areas which do not positively contribute to the resonant mode but dissipating thermal elastic energy. The k2eff obtained from the finite element modeling is as high as 8.7% which exceeds that of bulk acoustic wave (BAW) resonator by 1%.