High-Q Piezoelectric Lamb Wave Resonators based on AlN Plates with Chamfered Corners

A novel approach to the boost quality factor (Q) of Lamb wave resonators by chamfering the aluminum nitride (AlN) plate is investigated for the first time. It is well-known that the Q's of the AlN Lamb wave resonators are degraded due to energy dissipation through the support tethers. In this work, similar to the beveled edges used in AT-cut quartz resonators, the chamfered corners are utilized to trap vibration energy in the AlN plate to enhance the anchor Q's. Based on finite element analysis (FEA) simulated results, the AlN plate with chamfered corners can efficiently reduce mechanical vibrations in support tethers and trap more mechanical energy in the plate. The experimental results demonstrate that the loaded Q of the Lamb wave resonator is boosted from 2,041 to 3,016 and the minimum impedance is reduced from 87.4 Omega to 61.6 Omega by simply chamfering the AlN rectangular plate, showing a 1.48x increase in measured Q's.