To support the explosive growth of AI-powered applications, immersive extended reality (XR), and a hyper-connected Internet of Things (IoT), wireless systems must migrate to higher frequencies. The cmWave band (7–15 GHz), which strikes a balance between speed and coverage, is at the forefront of 6G planning. Yet, filtering technology has lagged behind: traditional waveguide filters are too bulky for mobile use, and existing acoustic filters suffer at higher frequencies. Being fragile, suspended thin-film devices complicate mass production. Due to these limitations, there is a pressing need to develop compact, durable, and cost-effective RF filters that can perform reliably at cmWave frequencies.
In a study (DOI: 10.1038/s41378-025-00949-9) published in Microsystems & Nanoengineering on May 8, 2025, researchers from the University of Science and Technology of China and the Hong Kong University of Science and Technology presented a scalable solution to this challenge. They introduced shear vertical surface acoustic wave (SV-SAW) radio frequency (RF) filters based on a layered 128°Y LiNbO3/SiO2/poly-Si/Si substrate, designed specifically for 6G cmWave applications. These filters not only meet the demanding performance criteria of high-frequency communication but also promise low manufacturing cost and compatibility with silicon-based semiconductor processing.
The team’s design leverages the unique piezoelectric properties of 128°Y-cut lithium niobate, enabling excitation of shear vertical acoustic waves with strong energy confinement. By embedding additional SiO2 and polycrystalline silicon layers between the piezoelectric layer and the supporting silicon substrate, the device achieves low insertion loss and excellent temperature stability. Experimental results reached center frequencies as high as 8.63 GHz, with insertion loss as low as 1.47 dB and 3-dB bandwidths up to 373 MHz. The resonators demonstrated high quality factors (Bode_Qmax up to 727) and high electromechanical coupling (k² ~ 8.9%). Moreover, the filters maintained performance across a wide thermal range with a temperature coefficient of −46 ppm/°C. Importantly, these were achieved using industry-compatible materials and techniques—laying a clear path toward scalable production.
“This work proves that high-frequency miniature-size RF filters can be both high-performing and manufacturable,” said Prof. Chengjie Zuo, corresponding author of the study. “Our SV-SAW design combines low cost with exceptional signal fidelity and thermal robustness. It’s the first time we've seen filters at this high frequency built on a solid silicon substrate, making it not only a scientific milestone but also a commercially viable innovation.”
The implications are wide-reaching. These SV-SAW filters could be integrated into 6G smartphones, routers, and base stations, dramatically improving data transmission while keeping production costs low. Their compatibility with standard semiconductor fabrication means they can be mass-produced using existing infrastructure. Beyond telecommunications, these filters have potential in aerospace, autonomous systems, and sensing applications—any field that demands compact and energy-efficient components operating at high frequencies. As the world edges closer to 6G deployment, this silicon-acoustic fusion offers a timely and transformative solution.
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References
DOI
10.1038/s41378-025-00949-9
Original Source URL
https://doi.org/10.1038/s41378-025-00949-9
Funding information
This work was supported in part by the National Natural Science Foundation of China under Grant 62231023, in part by the National Key Research and Development Program of China under Grant 2023YFE0202300, in part by the Hong Kong Innovation and Technology Commission under Grant MHP/007/22, in part by the University Synergy Innovation Program of Anhui Province under Grant GXXT-2023-002, in part by the Scientific Research Plan Program of Anhui Province under Grant 2024AH052041, in part by USTC Research Funds of the Double First-Class Initiative under Grant YD2100002014, in part by the University of Science and Technology of China (USTC) Center for Micro and Nanoscale Research and Fabrication, and in part by USTC Institute of Advanced Technology.
About Microsystems & Nanoengineering
Microsystems & Nanoengineering is an online-only, open access international journal devoted to publishing original research results and reviews on all aspects of Micro and Nano Electro Mechanical Systems from fundamental to applied research. The journal is published by Springer Nature in partnership with the Aerospace Information Research Institute, Chinese Academy of Sciences, supported by the State Key Laboratory of Transducer Technology.