Fish Scale-shaped Acoustic Reflector Array for Quality Factor Enhancement of AlN-on-Silicon MEMS Resonator

This paper presents a strategy for quality factor (Q) enhancement of MEMS (micro-electro-mechanical systems) resonator, based on reducing anchor loss. Q is an extremely important property, which affects the practical application of MEMS resonator in many fields. The important measure to improve Q is to reduce anchor loss that is the dominant energy loss of thin-film piezoelectric-on-silicon (TPoS) MEMS resonators. So, we propose a fish scale-shaped acoustic reflector array to reflect the leaked acoustic wave and it thus significantly reduce the anchor loss. Compared with the traditional single reflector, the proposed reflector array can more effect suppress the energy dissipation. Moreover, we integrate the reflector array inside resonant body rather than the traditional design that place reflector at the behind of tethers, which can observably enhance the Q without increasing the occupied area. The Q of the proposed structure is obtained by using finite-element-analysis (FEA) simulation, which achieved a 3.5-fold improvement (i.e. Qu=17, 414) compared with the traditional design (i.e. Qu=4, 913).