Quality factor enhancement in Lamb wave resonators utilizing butterfly-shaped AlN plates

A novel technique to enhance the quality factor (Q) of Lamb wave resonator by utilizing an aluminum nitride (AlN) plate formed in a butterfly shape is investigated in this paper. In the conventional design, the Q´s of the micromachined Lamb wave resonators are largely harmed by the energy dissipation through the support tethers. The finite element analysis (FEA) simulation results show that the butterfly-shaped topology can efficiently change the displacement field in the AlN plate and reduce the vibration in the support tethers. The unloaded Q of the resonator is raised from 3,360 to 4,758 by simply using of the butterfly-shaped AlN plate with a tether-to-plate angle α = 59°, representing a 1.42× increase. The experimental Q´s are also in good agreement with the anchor loss Q´s computed using the PML-based FEA method.