低串扰、低损耗高频超声阵列换能器关键技术研究

The project focuses on the demand of low-crosstalk and low-loss ultrasonic array transducers applied in future high-frequency (above 100 MHz) ultrasonic detection and imaging. To remove the technological bottleneck of isolation kerfs of high aspect ratio, the project will explore the method of bottom-up and self-defined patterning of piezoelectric films, a ridge-type restraint structure and dense film growth technology. The effect and principle of restraint structure on lateral growth of thin films will be studied. The effects of electric field, lattice matching, solution composition, concentration, temperature and reaction time on the grain size, grain orientation, density, growth rate, uniformity and electromechanical conversion coefficient of the thin films will be investigated. The physical and chemical laws in the reaction processes such as the kinetics, charge transfer and molecular assembly will be found. The interface effect, load effect and compensation method will be investigated. The breakthrough and innovation of the preparation method, structure design, process flow and film forming principle can be obtained, which lays the foundation for the realization of low-crosstalk and low-loss high-frequency ultrasonic array transducers. After carrying out this project, the following achievements will be brought forth: working frequency of 100MHz-300MHz, crosstalk below -20dB, kerfs of aspect ratio higher than 6:1, 4-6 publications in SCI/EI journals, more than 2 patents, and 1-2 master and doctor.

针对未来高频（100 MHz以上）超声检测与成像领域对低串扰、低损耗超声阵列换能器的应用需求，解决高深宽比隔离缝隙的制备技术瓶颈，探索自下而上的自定义图形化压电薄膜生长方法、田埂式束缚型结构、压电材料致密成膜技术，研究束缚型结构抑制薄膜横向生长的作用和原理，阐明电场、晶格匹配、溶液成分、浓度、温度、反应时间等因素对薄膜晶粒、晶向、致密度、生长速率、均匀性和机电转换系数等特性的影响，发现反应过程的动力学、电荷传输、分子组装等物理、化学规律，掌握图形化生长中的界面效应、负载效应及补偿方法，取得制备方法、结构设计和工艺流程、成膜原理的突破和创新，为实现低串扰、低损耗的高频超声阵列换能器奠定基础。实现高频氧化锌阵列：中心工作频率100 MHz - 300 MHz，阵元间串扰 < -20 dB，隔离缝隙深宽比 > 6:1；发表SCI/EI论文4-6 篇；申请发明专利2 项以上；培养1-2 名研究生。

本项目针对未来高频（100 MHz以上）超声检测与成像领域对低串扰、低损耗的超声阵列换能器的应用需求，在高频超声换能器理论模型、氧化锌薄膜成膜理论、微纳结构制备方法、高频超声阵列换能器的高频激励信号产生方法以及高频超声换能器性能测试系统等方面开展研究。建立了高频超声阵列换能器的声波传输特性和声阻抗匹配、固液耦合等仿真模型，分析了器件参数对超声换能器性能的影响，设计了高频超声阵列换能器结构；发现了反应过程的动力学、电荷传输、分子组装等物理、化学规律，掌握了图形化生长中的界面效应、负载效应及补偿方法，制备成功致密氧化锌薄膜，开发了具有自主知识产权的高精度、微型化、批量化新型压电阵列器件的构筑技术，为实现高频超声阵列换能器奠定了基础。设计了前置微分电路式三极管雪崩击穿脉冲发生电路，以产生高频超声换能器带宽、串扰、机电转换效率等性能测试所需的高频激励信号。研制了一套高频超声换能器脉冲-回波测试系统，可实现换能器中心频率、带宽、串扰、机电耦合系数、焦距、景深等多种电学和声学参数的测量。实现了高频氧化锌阵列达到中心频率100 MHz - 300 MHz，阵元间串扰 < -20 dB，隔离缝隙深宽比 > 6:1；发表SCI/EI论文13篇；取得该研究方向的核心自主知识产权，申请发明专利7 项；培养2 名研究生。