基于热动力回馈的有源微机电谐振器研究

Micro-electro-mechanical systems (MEMS) sensor is one of the key components for Internet of Things. As the core sensing element of a resonant MEMS sensor, MEMS resonator is facing the challenges of low quality factor (Q) and difficulty in Q tuning, which impose significant impact on the performance of the sensor (i.e. sensitivity and resolution), and thus constrain the practical application and further development of resonant MEMS sensors. The operation of silicon piezoresistive MEMS resonators involve multiple physical domains (i.e. thermal, mechanical and electrical), the mutual coupling between different physical domains results in a so-called “thermodynamic feedback effect” that can dramatically change Q of the resonator. Thus, this project will study the active MEMS resonator based on thermodynamic feedback, investigate the mechanism of thermodynamic feedback and the factors that may impact the its feedback efficiency, propose Q tuning method and realize high Q active MEMS resonator. The major research content includes (1) the mechanism and modeling of thermodynamic feedback based on coupled multi-physics analysis, (2) key factors that influence the thermodynamic feedback efficiency, (3) design and experimental validation of the active MEMS resonators. This project is an advancement of current research progress on the high-performance active MEMS resonators. Its outcome will lead to a comprehensive solution for device simulation, modeling, design and characterization. It can benefit the research, development and application of high-performance MEMS sensors.

微机电（MEMS）传感器是物联网的关键元器件之一。微机电谐振器作为谐振式微机电传感器的核心敏感单元，目前存在品质因数（Q值）较低且调控较难的问题，直接影响传感器的灵敏度和分辨率等重要指标，由此极大地制约了谐振式微机电传感器的应用与发展。压阻式微机电谐振器涉及到热-力-电等多个物理场，其相互耦合作用而产生的热动力回馈效应可使得谐振器Q值显著变化。因此，本项目拟研究基于热动力回馈的有源微机电谐振器，探索热动力回馈效应机制及影响回馈效率的因素，提出调控方法并实现具有高Q值的有源微机电谐振器。主要的研究内容如下：（1）基于多物理场分析的热动力回馈效应机理及建模研究；（2）热动力回馈效率影响因素研究；（3）有源微机电谐振器的设计与实验验证。本项目是对高性能有源微机电谐振器研究的进一步发展，其成果可形成一套较为完善的器件建模、设计、加工以及测试方案，对于推动高性能微机电传感器的研发及应用具有重要意义。

微机电（MEMS）传感器是物联网的关键元器件之一。MEMS谐振器作为谐振式微机电传感器的核心敏感单元，目前存在品质因数（Q值）较低且调控较难的问题，直接影响传感器的灵敏度和分辨率等重要指标，由此极大地制约了谐振式MEMS传感器的应用与发展。压阻式MEMS谐振器涉及到热-力-电等多个物理场，其相互耦合作用而产生的热动力回馈效应可使得谐振器Q值显著变化。本项目对硅基压阻式MEMS谐振器的热动力回馈效应开展了深入研究：研究了温度对热动力回馈效应的影响，建立温度影响相关参数的函数模型，在此基础上建立了完整的三维多物理场耦合有限元模型，并实现热动力回馈效应对Q值影响的准确预测；基于所建立的三维多物理场耦合有限元模型，设计并实现了高机电耦合系数、高储能能力、低频率偏移的体模态压阻式MEMS谐振器；开发并改进了基于SOI-MEMS的压阻式MEMS谐振器加工工艺，通过选择性掺杂实现了电极的低欧姆接触电阻的同时，保证了谐振器的具有较高压阻换能和较好的线性响应。本项目的开展，对于开发具有高机电换能效率的硅基MEMS传感器具有一定的指导意义。相关的工作发表SCI期刊论文3篇，EI会议论文5篇；进行国际会议邀请报告1次；申请发明专利3项，其中2项已授权；培养1名博士研究生，3名硕士研究生。

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