BAW Resonator with an Optimized SiO₂/Ta₂O₅ Reflector for 5G Applications

Abstract

In the present work, a lithium niobate (LN) 43°Y cut LN film is transferred onto a substrate with 11 layers of SiO 2 /Ta 2 O 5 and solidly mounted resonators with a reflector are successfully fabricated with the multilayer structure. The design method and fabrication process are demonstrated. The finite element model and the Mason model are used. Scanning electron microscopy and atomic force microscopy are used to characterize film quality. An optimized design of a Bragg reflector to suppress the leakage of acoustic energy by thickness shear mode is proven to be effective. The influence of the reflector on parasitic modes and filter out-of-band suppression is analyzed. The resonator for 3.5 GHz shows an effective electromechanical coupling coefficient of 17.9%, and the figure of merit is 40.4, which is suitable for band pass filter on the N78 band with high rejection.

Enhancing Isolation in Solidly Mounted Resonators for Brain Implantable Microbots

“…They obtained a quality factor of 130-150, and for a multi-layer λ/4 reflector it was between 18 and 67. Closer to our designs, Lu Lv et al used an eleven λ/4 layers stack with a Q-factor of 165 at 3.5 GHz [15]. These values, already considered adequate for the isolation from the substrate, are far from the results that belong to our models, already mentioned.…”

Aluminum Nitride-Based Adjustable Effective Electromechanical Coupling Coefficient Film Bulk Acoustic Resonator

“…The effective electromechanical coupling coefficient ( K eff 2 ) of an FBAR is a vitally important parameter closely related to the bandwidth of the filter [ 12 ]. Generally, it is necessary to reasonably design the K eff 2 of the FBAR device to meet the bandwidth requirements of different frequency bands.…”