Novel Low-Voltage Silicon MEMS Resonators With High f×Q Product Inspired From Bell Plates

This article presents the design, simulation, fabrication, and characterization of the first "bell plate" microelectromechanical resonators in silicon-oninsulator (SOI) technology. These resonators are actuated by electrostatic force and exhibit a high-quality factor of up to 160 at 180 kHz resonant frequency, resulting in an f × Q product exceeding 28 GHz. Several designs were explored, and all (2, 0)-mode resonators systematically outperformed the first clamped-free mode in terms of Q-factor. This mode was investigated through finite element simulations and experimental measurements and compared to the first clamped-free mode. The resonators were actuated with dc lower than 1 V and ac lower than 250 mV at resonance, and their mechanical motion was measured by laser Doppler vibrometry. Dynamic characterization was performed both in open-loop and closed-loop configurations. The temperature coefficient of frequency (TCF) of the (2, 0)-mode is mainly dominated by the silicon properties, leading to a value equal to -48 ppm/°C. These results demonstrate that MEMS resonators with bell plate geometries are promising for high-Q applications such as sensing and time references.