A Q-factor Boost Strategy for High-Order Width-Extensional Mode MEMS Resonators by Varied Unit Length

It is a longstanding issue that high-order width-extensional (WE) piezoelectric microelectromechanical system (MEMS) resonators suffer low quality factors (Q-factors). In this study, it is observed that the mode distortion occurs in each unit when it couples with each other to constitute the high-order WE-mode resonator, leading to a decreased Q-factor. Based on this finding, we propose a new Q-factor boost strategy by improving mode matching degree between adjacent units from the view of dividing the high-order resonator into units. Both simulation and experimental results show a significant improvement in mode matching degree between adjacent units with varied unit length. Resonator's Q-factor measured in air improved by 53% compared with the conventional resonator with constant unit length. It is believed that the proposed strategy could apply to other WE-mode MEMS resonators with different orders or dimensions; and Q-factor can be further improved by combining the proposed method with traditional energy reflection methods. [2023-0201]