Design and Fabrication of LAMB Wave Resonator Based on 15% Scandium-Doped Aluminum Nitride Thin Film

Abstract

This work reports the Lamb wave resonator based on 15% Sc-doped (Al0.85Sc0.15N) thin films using magnetron co-sputtering. The dispersion characteristics of Lamb wave resonators are simulated for Al0.85Sc0.15N. The dispersion properties of Lamb waves on the coupling coefficient in Al0.85Sc0.15N thin films were simulated. An electromechanical coupling factor of nearly 4% can be obtained for S0 mode Lamb wave resonators. Optimized design using 3D finite element analysis (FEA) with perfectly matched layer (PML) to improve quality factor. The resonator fabrication process is discussed in detail. Al0.85Sc0.15N thin films with a 1.7° FWHM of (0002) rocking curve were obtained. Al0.85Sc0.15N Lamb wave resonators operating at approximately 310 MHz were fabricated. A high electromechanical coupling coefficient (kt²) of 3.7 % is reported, with the loaded quality factor of 1165.7 and unloaded quality factor of 1253.2, respectively.