An Acoustic Resonator with 18% Effective Electromechanical Coupling Exhibiting Low TCF and Improved Thermal Conductivity at 8 GHz

In this work, a high-frequency acoustic resonator is designed. The resonator is a three-layer composite structure composed of lithium niobate (LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> /LN), silicon dioxide (SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) and aluminum nitride (AlN), which excites Lamb waves through a lateral electric field. The influence of design parameters on the thickness shear (TS) type Lamb wave mode of the resonator is systematically studied through the finite element analysis (FEA) method. When the thickness ratio of AlN to LN to SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> approaches 1:4:15, the S4 mode of the resonator obtains a temperature coefficient of frequency (TCF) of −5.2 ppm/K, an effective electromechanical coupling of 18%, and improved thermal conductivity at 8 GHz. The achieved specifications are adequate to meet the demands of 5G frequency bands, with broad application prospects.