基于高磁致伸缩薄膜材料与磁电耦合的射频微机电回转器研究

Radio frequency non-reciprocal devices are key enablers for full-duplex radios that can simultaneously transmit and receive over the same bandwidth. Conventional ferrite based nonreciprocal devices operate exclusively in the electromagnetic (EM) domain and therefore have sizes comparable to EM wavelength. As a result, they are typically bulky and difficult to integrate at chip-scale to synthesize more complex non-reciprocal networks with advanced signal processing capabilities. To drastically reduce size of non-reciprocal devices while maintaining competitive performance, this proposal takes inspiration from miniaturization approaches used in other front-end components, such as RF filters. We propose to develop a new RF non-reciprocal gyrator based on magnetoelectric thin film heterostructure. Magnetoelectric composite devices, benefiting of small size, low power consumption, large-scale integration, multi-mode operation, etc., are important research topics and have significant potential in many prospects. Recently, we have investigated the process and high frequency parameters of a variety of piezoelectric and piezomagnetic thin film materials, established the device prototype and process flow, simulated the high frequency characteristics of the device, and verified the feasibility of the MEMS gyroscope. This project aims to design and manufacture high performance MEMS magnetoelectric gyrator operating at thickness excitation resonant mode. We aim to explore the different sputtering deposition processes of rare earth alloy materials and analyze the influence of boron doping and alumina heterogeneity on key parameters, such as high-frequency magnetic properties, piezoelectric coupling coefficient, magnetostrictive coefficient, magnetostrictive coefficient, and magnetoelectric interface coupling mechanism, to develop high performance non-reciprocal MEMS magnetoelectric gyrator.

射频非互易性器件是实现全双工无线电的关键器件，在射频微电子和5G通信领域具有巨大的应用价值。传统基于铁氧体材料的分立非互易器件, 体积庞大，价格昂贵，难以与芯片集成形成具有先进信号处理能力的更复杂非互易网络。针对这一技术难点，本项目提出采用压电与压磁相结合的磁电复合结构，利用层状复合结构在厚度方向共振时发生磁电转换，并依靠电压-电流的回转来产生反相位响应，从而实现构建双端口非互易性回转器。前期预研工作已建立了器件原型与工艺流程，根据薄膜材料高频参数仿真分析了器件特性，初步验证了磁电复合微机电回转器的可行性。 本项目将针对高性能微机电回转器的设计和加工难度，探究稀土合金材料的不同溅射沉积工艺，分析硼掺杂与氧化铝异质结构对磁学特性的影响，获取压电耦合系数、高频电磁参数、磁致伸缩系数等关键参数，研究磁致伸缩薄膜材料与氮化铝压电薄膜界面的耦合机理，开发基于磁电耦合的非互易性微机电回转器的技术路线。

项目完成了高质量氮化铝钪薄膜沉积工艺以及基于该薄膜的Lamb波谐振器设计、铁镓硼磁性薄膜的磁控溅射机理与薄膜质量与多层复合薄膜结构的静态和动态特性以及磁电耦合回转器。利用直流脉冲共溅射系统，得到了不同Sc浓度的AlScN薄膜。通过调控N2流量，得到了1.76°的最佳FWHM以及无异向晶粒的AlScN薄膜。在等离子体刻蚀中，通过增加刻蚀气体提高刻蚀各向异性，并增加功率提高刻蚀速率，实现了超过100 nm/min的刻蚀速度和75°以上的刻蚀截面。此外，成功制备了基于AlScN薄膜的高机电耦合兰姆波谐振器，推出了共享服务氮化铝工艺平台。成功制备了硼组分为12%的FeGaB磁性薄膜，表征了2–20GHz的铁磁共振吸收谱，薄膜磁矫顽场Hc低于3Oe。.在磁电耦合回转器中，实现了基于高阶压电轮廓模式谐振器的磁电耦合回转器。这种新型的MEMS回旋器，利用压电和洛伦兹力的混合传导；回转器转换效率是由洛伦兹力和压电转导的组合决定的。通过利用具有较大压电耦合系数的氮化铝钪（AlScN）和可变的外部磁场，实现了芯片级的回转器。在大约388MHz和1.65T的磁场偏压下工作时，具有6.3%的大分数带宽（FBW）。 高性能AlScN薄膜以及更大的FBW和更容易的阻抗匹配显示了射频通信和信号处理的潜力。.在项目执行期间，发表了高水平SCI学术论文20篇，申请专利2项，发表专著1本，完成项目预期目标。