Reducing anchor loss In thin-film aluminum nitride-on-diamond contour mode MEMS resonators with support tethers based on phononic crystal strip and reflector

In this paper, we report on (1) the proposed support tether configuration based on phononic crystal (PnC) strip to reduce the anchor loss in the thin-film piezoelectric-on-diamond (TPoD) contour mode microelectromechanical systems (MEMS) resonators, namely the \(100^0\) oriented thin-film aluminum nitride (AlN)-on-diamond wine glass (WG) and width shear (WS) mode MEMS resonators, (2) impacts of the geometrical dimensions on the band gaps of the proposed PnC structure, (3) evaluation of the performance of the Q improvement between the proposed support tether configuration and the one based on the reflector presented by B P Harrington and R Abdolvand. The designed resonators operate at approximately 115 and 156 MHz corresponding with the WG and WS modes. The band gap width covering these two operating frequencies is 30.2 and 20.6 MHz, respectively. The maximum Q of the WG mode resonator with five-unit cell PnC strip based support tethers achieves up to 398.5 % over that of the same resonator with reflector based support tethers. Similar to the WS mode one with three-unit cell PnC strip based support tethers, this Q is up to 591.1 %. The average Q of the WG mode resonator with PnC strip based support tethers over the maximum Q of the same one with different reflectors is enhanced about 964.4, 952.9, 364.2 and 4599.5 %. For the WS mode resonator, these Q values are up to 2388.8, 1830.4, 528.2 and 2384.5 %. The finite element (FE) analysis in COMSOL Multiphysics software (COMSOL) is utilized to simulate the proposed PnC strip as well as the WG and WS mode resonators.