X-Cut Lithium Niobate Laterally Vibrating MEMS Resonator With Figure of Merit of 1560

This letter reports on the design, fabrication, and testing of an X-cut lithium niobate laterally vibrating resonator operating around 50 MHz and exhibiting a record figure of merit–FoM = product of electromechanical coupling ( $k_{t}^{2}$ ) and quality factor at a resonance ( $Q_{s}$ )–of 1560. For practical applications, the individual resonator is arranged in a large array so as to achieve a static capacitance around 1 pF, while still preserving a high FoM of 570. Modeling of anchor losses through finite element analysis is used to guide the design of these resonators, which simultaneously exhibit high electromechanical coupling ( $k_{t}^{2} > 30$ %) and high quality factor ( $Q_{s} > 5000$ ) in vacuum.l [2018-0097]