Lu Hao, Hao Xiaorun, Yang Ling, Hou Bin, Zhang Meng, Wu Mei, Dong Jie, Ma Xiaohua
School of Microelectronics, Xidian University, Xi'an 710126, China.
Micromachines (Basel). 2025 Feb 11;16(2):205. doi: 10.3390/mi16020205.
AlN-based bulk acoustic wave (BAW) filters have emerged as crucial components in 5G communication due to their high frequency, wide bandwidth, high power capacity, and compact size. This paper mainly reviews the basic principles and recent research advances of AlN-based BAW resonators, which are the backbone of BAW filters. We begin by summarizing the epitaxial growth of single-crystal, polycrystalline, and doped AlN films, with a focus on single-crystal AlN and ScAlN, which are currently the most popular. The discussion then extends to the structure and fabrication of BAW resonators, including the basic solidly mounted resonator (SMR) and the film bulk acoustic resonator (FBAR). The new Xtended Bulk Acoustic Wave (XBAW) technology is highlighted as an effective method to enhance filter bandwidth. Hybrid SAW/BAW resonators (HSBRs) combine the benefits of BAW and SAW resonators to significantly reduce temperature drift. The paper further explores the application of BAW resonators in ladder and lattice BAW filters, highlighting advancements in their design improvements. The frequency-reconfigurable BAW filter, which broadens the filter's application range, has garnered substantial attention from researchers. Additionally, optimization algorithms for designing AlN-based BAW filters are outlined to reduce design time and improve efficiency. This work aims to serve as a reference for future research on AlN-based BAW filters and to provide insight for similar device studies.
基于氮化铝（AlN）的体声波（BAW）滤波器因其高频、宽带宽、高功率容量和紧凑尺寸，已成为5G通信中的关键组件。本文主要综述了基于AlN的BAW谐振器的基本原理和最新研究进展，BAW谐振器是BAW滤波器的核心。我们首先总结了单晶、多晶和掺杂AlN薄膜的外延生长，重点关注目前最流行的单晶AlN和钪铝氮（ScAlN）。接着讨论扩展到BAW谐振器的结构和制造，包括基本的固态安装谐振器（SMR）和薄膜体声波谐振器（FBAR）。新型扩展体声波（XBAW）技术被视为增强滤波器带宽的有效方法。混合声表面波/体声波谐振器（HSBR）结合了BAW和谐振器的优点，显著降低了温度漂移。本文进一步探讨了BAW谐振器在梯形和晶格BAW滤波器中的应用，突出了其设计改进方面的进展。拓宽滤波器应用范围的频率可重构BAW滤波器已引起研究人员的广泛关注。此外，概述了用于设计基于AlN的BAW滤波器的优化算法，以减少设计时间并提高效率。这项工作旨在为未来基于AlN的BAW滤波器研究提供参考，并为类似器件研究提供见解。
