Giant Piezoelectricity In Sodium Niobate FBAR Achieving Coupling Coefficient Of 21.6% At 3 GHz

Bulk Acoustic Wave (BAW) resonators are important for 5G and sub-6GHz telecommunications. While lithium niobate films boast high electromechanical coupling coefficients, they face spurious mode issues. In contrast, Aluminum Nitride (AlN) and Sc-doped AlN have fewer spurious modes, though Sc-doping introduces stress and frequency non-uniformity problems. We introduce sodium niobate (NaNbO
3
) as a new piezoelectric material, which avoids spurious modes and enhances the electromechanical coupling coefficient. Finite Element Analysis (FEA) of a NaNbO
3
Film Bulk Acoustic Resonator (FBAR) demonstrated an improved electromechanical coupling coefficient (21.6%) over that of Sc
0.3
Al
0.7
N (18.1%).