High-Q multi-frequency ring-shaped piezoelectric MEMS resonators

Abstract

While MEMS resonators are emerging as a promising integrated clock-chip solution, often quality factor (Q) and spurious modes limit device performance. Moreover, realizing high-Q and multi-frequency simultaneously in a piezoelectric MEMS resonator is still comparatively difficult. In this research, a ring-shaped MEMS resonator outfitted with optimized electrodes was proposed to significantly suppress undesired resonant modes and then boosts the Q of rest resonant modes. To systematically explore the proposed design, numerical and experimental investigations were performed, revealing that the presence of optimized electrodes helps to counterpoise distributions of surface charge density and displacement current density in vertical direction, thereby results in the suppression of spurious modes. The maximum unloaded quality factor (Qu) of the fabricated ring-shaped resonators was up to 10,069 ​at 83.59 ​MHz. The measurement results of the resonator with optimized electrodes yielded three resonant modes with Qu large than 5,000, indicating that the high-Q and multi-frequency ring-shaped resonator was satisfactorily achieved.