相比于传统的体压电超声换能器，压电式微机械超声换能器（PMUT）因体积小、功耗低、频率调控灵活、易于CMOS集成等显著优势，正在诸多领域发挥日益重要的作用。随着应用需求的不断拓展，同样也对PMUT的带宽、灵敏度等关键性能指标提出了新的挑战。该文首先介绍了PMUT器件结构和工作机理，并以PMUT的空腔制备方法为分类依据，概述了刻蚀法、牺牲释放法、表面键合法、硅迁移法制备PMUT的工艺方案及其优缺点。从压电材料、器件结构、电极激励、声学匹配四个方面系统阐述了PMUT性能优化策略的研究现状。以高压电系数和低介电常数为压电材料的优化目标，通过掺杂、改性及工艺优化等技术手段改善压电材料的性能指标；基于振动模态转变、残余应力调控、声学结构集成及阵列布局等策略，改变PMUT结构实现性能指标优化；通过配置PMUT电极的静态布局及动态激励信号参数实现PMUT的谐振频率、带宽及灵敏度的调控；借助外部材料或结构对PMUT进行声学匹配与封装，改善PMUT的声学特性。最后讨论了当前PMUT的工艺及性能优化方案面临的主要挑战与发展趋势，为PMUT的未来研究与实际应用提供参考。

Compared to traditional bulk piezoelectric ultrasonic transducers, piezoelectric micromechanical ultrasonic transducers (PMUT) play a crucial role in various application fields due to their advantages such as small size, low power consumption, flexible frequency regulation, and the possibility of integration with CMOS. With the continuous expansion of application demands, new challenges are also posed to key performance indicators of PMUT, such as bandwidth and sensitivity. The article introduces the structure and working mechanism of PMUT, and based on the cavity fabrication methods of PMUT summarizes the fabrication processes and their advantages and disadvantages, including etching, sacrificial release, surface bonding, and silicon migration methods. The article summarizes the research status of PMUT performance optimization strategies from four aspects: piezoelectric materials, device structures, electrode excitation, and acoustic matching.

With high piezoelectric coefficient and low dielectric constant as the optimization objectives for piezoelectric materials, the performance indicators of piezoelectric materials are improved through techniques such as doping, modification, and fabrication process. Based on strategies such as vibration mode transformation, residual stress regulation, acoustic structure integration, and array layout, the PMUT structure is modified to achieve performance optimization. By configuring the static layout of PMUT electrodes and the parameters of the dynamic excitation signals, it is possible to regulate the resonance frequency, bandwidth, and sensitivity of the PMUT. Acoustic matching and encapsulation of the PMUT with external materials or structures further enhances its acoustic characteristics. Finally, this paper discusses the main challenges and future development trends faced by PMUT, to provide a reference for the future research and practical application of the technology.