Design, Fabrication, and Characterization of Dual-Mode AlN Lamb Wave Resonators Above 2 GHz

The miniaturization and integration of radio frequency (RF) front-end are research hotspots in academia and industry. Dual-mode acoustic resonators have great potential in this area by reducing the number of devices used. This work proposes a novel dual-mode Lamb wave resonator (DLWR) with two different interdigital transducer (IDT) arrays. A simplified DLWR (S-DLWR) with high fabrication process feasibility is also studied in detail. The characteristics of DLWR and S-DLWR are investigated by finite element analysis (FEA) simulation while a propagation model of the acoustic modes is established as the theoretical support. Based on the optimized design and proposed fabrication process, S-DLWRs are successfully fabricated. The measured result shows that two main acoustic modes are excited simultaneously, whose resonance frequencies can be adjusted independently by changing the thickness of corresponding IDT arrays, which shows great potential to accelerate the development of dual-mode resonators in RF filters and other important applications.