Investigation of 20% Scandium-doped Aluminum Nitride films for MEMS laterally vibrating resonators

RF filtering technologies based on piezoelectric MEMS resonators have been successfully developed and commercialized in the past decade thanks to their size and outstanding performance. The challenge to enhance filter's performance in terms of lower insertion losses and wider bandwidth still makes for an active research topic, especially spurring the interest for new classes of materials such as doped-AlN [1] and thin films of lithium niobate [2]. In this work, we investigate the use of 20% Scandium-doped Aluminum Nitride (ScAlN) thin films for the making of laterally vibrating MEMS resonators (LVRs). The main goals of our work are to demonstrate: 1) a higher k
_t
²
(~ 2x) compared to non-doped AlN, 2) ease of fabrication process compared to lithium niobate thin films [3], 3) fabrication of multi-frequency devices (250 MHz-1 GHz) on the same wafer.