摘要
We propose an apodization technique based composite thin Film Bulk Acoustic wave Resonator (c-FBAR) design to enable the displacement and strain energy confinement at the central section of the resonator while in operation at the resonance mode. Sinc-shaped AlN on SOI apodized c-FBARs are designed to attain close to 90% energy localization. In this work, single crystal silicon as the mechanical layer and AlN piezoelectric material as the transducer layer of the resonator implemented by InvenSense Inc.&null AlN MEMS-CMOS platform renders an asymmetric feature to the traditional FBAR resonator. The nature of composite Thin film Piezoelectric on Substrate (TPoS) FBAR resonators in the Super High Frequency (SHF) range is studied in detail. Furthermore, a complete de-embedding procedure to extract the resonator parameters from the CMOS+MEMS measured data is also explained meticulously. A complete equivalent circuit modeling for c-FBAR operating in the SHF is provided. Measurement data statistics show that sinc c-FBAR features superior electromechanical coupling coefficient (kteff2) than that of pentagon c-FBAR. As a result, we successfully demonstrate a sinc c-FBAR resonator operating at 3.264 GHz with an electromechanical coupling coefficient of 2.12%, a loaded quality factor (Q) of 790 and an unloaded Q of 2,507.