基于Si-SOI键合的微电容超声波换能器设计

发布时间：2018-07-10 12:07

本文选题：MEMS + CMUT　；参考：《中北大学》2014年硕士论文

【摘要】：微电容超声波换能器（CMUT）具有高灵敏度、宽频带、高机电转换效率、硅材料与介质阻抗匹配好、易于加工尺寸多样的微型器件、适合制造大阵列、批量化生产等优势，在工业控制、环保设备、医疗设备、航空航天及水下探测等领域有迫切的需求和广泛的应用前景，因此对CMUT的研究具有极其重要的科研价值和实用意义。本文基于平板电容原理，结合Si-SOI低温键合技术，，设计了一种引线交错式的CMUT结构，期望能减小器件的寄生电容，降低电容检测难度，从而提高换能器的灵敏度。本论文针对器件原理和设计方法、器件加工的关键技术等开展了较为详细的研究，为器件的设计及加工提供技术积累和实验支持。本论文具体研究内容如下：（1）对CMUT进行了理论分析。在机械域，根据振动理论，分析了在均布载荷及静电力作用下薄膜振动行为；从力-电耦合的角度，建立器件的平行板电容模型，得到了CMUT结构的塌陷电压、最大发射声压、接收灵敏度；采用机电类比的方法，建立了等效电路模型，得到薄膜机械阻抗、静态电容、转换系数等参数表达式，建立了完善的CMUT理论体系。（2）通过MATLAB仿真，得到关键性能参数与结构尺寸之间的关系，确定了结构尺寸；利用ANSYS对所设计结构进行了单一场的机械域仿真和多场耦合的静电-机械耦合仿真，得到了器件塌陷电压、工作模式下的谐振频率、所施加的交流电压最大值；通过MATLAB/SIMULINK仿真了所设计结构的发射/接收性能，验证了结构的合理性。（3）结合当前工艺水平，设计了基于Si-SOI低温键合技术的CMUT的工艺流程和加工版图，完成了加工。对其关键工艺、关键步骤进行了仿真和实验研究,包括热氧、离子注入、Si-SOI低温键合、SOI衬底硅的腐蚀等。得到了简单、合理的CMUT加工新方法。（4）利用激光显微镜、拉曼光谱仪、微系统分析仪、阻抗分析仪，对换能器进行初步测试，包括形貌测试、残余应力测试、谐振频率测试、发射性能测试、电容及谐振频率的一致性测试，验证了换能器的性能。
[Abstract]:Micro capacitive ultrasonic transducer (CMUT) has the advantages of high sensitivity, wide frequency band, high electromechanical conversion efficiency, good matching between silicon material and dielectric impedance, easy processing of micro devices of various sizes, suitable for manufacturing large arrays and mass production, etc. In the fields of industrial control, environmental protection equipment, medical equipment, aerospace and underwater detection and other fields, there is an urgent need and wide application prospects, so the research of CMUT has extremely important scientific research value and practical significance. Based on the principle of plate capacitance and the Si-SOI low temperature bonding technology, this paper designs a kind of CMUT structure with lead interleaving, which is expected to reduce the parasitic capacitance of the device, reduce the difficulty of capacitance detection, and improve the sensitivity of the transducer. In this paper, the principle and design method of the device, the key technology of device processing and so on are studied in detail, which provides the technical accumulation and experimental support for the design and fabrication of the device. The main contents of this thesis are as follows: (1) theoretical analysis of CMUT. In the mechanical domain, according to the vibration theory, the film vibration behavior under uniform load and electrostatic force is analyzed, the parallel plate capacitance model of the device is established from the angle of mechanical-electric coupling, the collapse voltage of CMUT structure and the maximum emission sound pressure are obtained. Receiving sensitivity, using electromechanical analogy method, the equivalent circuit model is established, and the expressions of membrane mechanical impedance, static capacitance and conversion coefficient are obtained, and a perfect CMUT theoretical system is established. (2) Simulation by MATLAB, The relationship between the key performance parameters and the structure size is obtained and the structure size is determined. The single-field mechanical simulation and the electrostatic-mechanical coupling simulation of the designed structure are carried out with ANSYS, and the device collapse voltage is obtained. The resonant frequency in the working mode, the maximum AC voltage applied, the emulation of the transmission / reception performance of the designed structure by MATLAB / Simulink, and the rationality of the structure are verified. (3) combining with the current process level, The process and layout of CMUT based on Si-SOI low temperature bonding technology are designed. The key processes and key steps are simulated and experimentally studied, including thermal oxygen, silicon corrosion of Si-SOI substrate bonded by ion implantation at low temperature, and so on. A simple and reasonable new method of CMUT processing is obtained. (4) the preliminary measurement of the transducer, including morphology test, residual stress test, using laser microscope, Raman spectrometer, microsystem analyzer, impedance analyzer, etc. Resonance frequency test, emission performance test, capacitance and resonant frequency consistency test, verify the performance of the transducer.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB552

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