Multilayer AlN-based Piezoelectric Resonator for High-Performance RF MEMS and Frequency-Agile Devices

Abstract

Next-generation wireless communication systems (5G/6G) demand acoustic resonators that simultaneously achieve high operating frequencies, large bandwidth, low loss, and compact, multi-band integration. Meeting these requirements calls for piezoelectric materials and device architectures that provide a high Figure of Merit (FoM) of quality factor (Q) × electromechanical coupling factor (kt2) – to minimize loss and maximize bandwidth – at microwave and millimeter-wave frequencies. In this work, we present a multilayer AlN-based thin-film resonator platform that incorporates advanced piezoelectric materials—including AlN, Al1-xScxN, and emerging variants such as Al1-xBxN—to push the performance limits of RF nano/micro-mechanical (N/MEMS) devices. These ultra-thin films and composite stacks enable enhanced electromechanical coupling and reduced acoustic loss, supporting high-frequency FBAR operation approaching the mm-wave regime with improved power handling [1]. Beyond linear filtering, the same MEMS resonators also form a versatile nonlinear platform capable of generating mechanical frequency combs through modal interactions and parametric coupling. When driven above critical thresholds, the devices exhibit multi-line, tunable spectral outputs, enabling chip-scale multi-frequency sensing and reconfigurable spectral processing. Ongoing advances in material engineering, electrode optimization, and heterogeneous integration strategies further enhance device robustness, nonlinearity controllability, and thermal stability [2]. Together, the multilayer AlN-based thin-film resonator platform and its nonlinear capabilities offer a unified path toward compact, high-performance RF filters and frequency-agile microsystems for future 5G/6G communication, sensing, and signal-processing applications. [1] M. Park, et al., EDL.,2024;[2]  M. Park, et al., JMEMS.,2019..

Bios

Dr. Mingyo Park joined the Department of Electrical Engineering at The Pennsylvania State University (PSU) as an Assistant Professor in Fall 2024 and will serve as the Thomas and Sheila Roell Early Career Professor in Fall 2025. She received her Ph.D. in Electrical and Computer Engineering from the Georgia Institute of Technology (GT) in 2022, where she also completed her Postdoctoral Fellowship from 2022 to 2024. Prior to her doctoral work, she earned her M.S. degree in 2016 and her B.S. degree in 2014 in Electrical and Electronic Engineering from Yonsei University in South Korea.

Dr. Park’s research focuses on developing innovative nano/microelectromechanical system (N/MEMS), emphasizing high-frequency acoustic resonators, nonlinear dynamics, and frequency-agile microsystems. Her work incorporates advanced piezoelectric and functional thin films platforms, as well as heterogeneous integration approaches such as thin-film transfer and multilayer architectures, to enable compact, high-Q, and thermally robust MEMS devices. These efforts support the development of next-generation technologies for 5G/6G communications, sensing, and signal-processing applications.