Design, Modeling and Fabrication of TPoS MEMS Resonators With Improved Performance at 1 GHz

In this work, the effects of physical dimensions such as length, width and thickness as well as the mode of vibration and the number of anchors on the performance of longitudinal thin film piezoelectric on silicon (TPoS) MEMS resonators have been studied. TPoS resonators, designed for a resonant frequency of around 1 GHz, were fabricated with a 4 mask CMOS compatible process. A $225~\mu \text{m}$ wide resonator excited in its $23^{rd}$ order had an unloaded quality factor of 9453 (in vacuum), which is the highest value reported so far for similar resonators, motional resistance of $107~\Omega $ and linear thermal coefficient of frequency of -28.4 ppm. We have also studied and modeled the different loss mechanisms in these devices. The model matches well with measured results for resonators of different geometries, modes of vibrations and number of anchors. [2020-0397]