Fast Method for the Design of Apodized BAW Resonators Including Border Ring With Optimized Lateral Modes

This work introduces a Quasi-3D modeling framework for the analysis of Film Bulk Acoustic Resonators (FBARs) and Solidly Mounted Resonators (SMRs) with Border Ring (BR), The method captures thickness-dependent behavior through precomputed dispersion curves, while discretizing the in-plane directions to account for lateral vibrations. Validation against Finite Element Method (FEM) simulations shows close agreement for FBARs and good accuracy for SMRs, despite the added complexity of the Bragg reflector and the presence of additional modes with lower cutoff frequencies. The model is further validated with measurements and applied to optimize SMR with BR designs, including apodized configurations, demonstrating its capability to suppress lateral modes in geometries that are computationally prohibitive for full 3D FEM. A computational analysis confirms that the Quasi-3D approach reduces simulation time and degrees of freedom by orders of magnitude compared to FEM. [2025-0203]