A Novel 2D Phononic Crystal-based Laterally-excited Bulk Wave Resonator

The commercialization of the laterally-excited bulk wave resonator (XBAR) in 5G communications are limited due to its poor mechanical reliability and heat dissipation. In this paper, a novel 2D phononic crystal-based XBAR (PnC-XBAR) is designed to selectively suppress the leakage of acoustic waves in the substrate. The properties of different types of substrates (the cavity, the Bragg reflector, and the phononic crystal) are analyzed using 2D-FEM. According to the simulations, the PnC substrate offers effective suppression for acoustic leakage and therefore enhances the mechanical quality factor (Q) of the resonator, as well as reduces the thermal stress. It also turns out that spurious modes like A1-3 are eliminated in the PnC-XBAR. This work provides a solution to subsequently enhancing of the mechanical reliability and heat dissipation of the XBAR, and has great application prospects.