A Manufacturable AlScN Periodically Polarized Piezoelectric Film Bulk Acoustic Wave Resonator (AlScN P3F BAW) Operating in Overtone Mode at X and Ku Band

This paper reports a manufacturable, Periodically Polarized Piezoelectric Film (P3F) Bulk Acoustic Wave (BAW) resonator using Aluminum Scandium Nitride (AlScN) materials operating in overtone mode at X and Ku band. P3F BAW technology benefits from a significantly larger film thickness than the traditional BAW thickness-frequency scaling approach, enabling a manufacturable, high quality-factor (Q), and high frequency resonator technology. A P3F material stack was realized using a combination of single and polycrystalline AlScN layers with desired polarity of layers as deposited, which enables volume manufacturing. An AlScN P3F BAW resonator was manufactured using XBAW®, a unique and patented transferred substrate process technology for next generation resonator and filter solutions. The fabricated P3F BAW resonators demonstrated 2nd overtone operation at 10.7 GHz & 18 GHz, and exhibits a FoM, (Qp × kt2) of 27 and 20, respectively. This result suggests that AlScN P3F BAW using overtone mode operation enables miniature, manufacturable, BAW RF filter technology for X band and higher frequencies.