可重构MEMS微波功率耦合器的设计及其可靠性研究

发布时间：2018-04-21 13:42

本文选题：可重构定向耦合器 + MEMS梁　；参考：《东南大学》2015年硕士论文

【摘要】：微波功率耦合器广泛地应用在军用和民用微波通讯领域。传统的微波功率耦合器的耦合度是固定的,所以本文提出了一种耦合度可变的可重构MEMS微波功率耦合器,并完成了该可重构MEMS微波功率耦合器的模拟、设计与制备。由于MEMS器件中加入了可动的MEMS梁结构,微观效应造成的可靠性问题成为MEMS器件设计中最难解决的关键问题。针对这一问题,本文还对MEMS梁的可靠性问题进行了一系列研究。本文的主要研究内容及其创新点包括：(1)基于GaAs MMIC工艺,设计了一种可重构MEMS微波功率耦合器。利用HFSS优化设计后的耦合器中心频率为35GHz,在35GHz处可实现7.989dB和10.62dB两种不同的耦合度。在30到40GHz频率范围内,该耦合器在两种状态下的S11小于-15dB,隔离度大于15dB。以上内容的创新之处在于,该耦合器的副线上设计了一种带有悬臂梁的双端梁结构来实现耦合度的调节；该耦合器与传统的双线定向耦合器在同等性能下基本具有相同的尺寸,相比与其它的可重构祸合器在尺寸上有明显的优势。(2)基于粘附会影响MEMS梁的振动频谱的原理,提出了利用振动实验来检测粘附问题的方法。根据振动实验的实验结果,总结了三种常见的振动频谱对应的粘附状态,其中只有振动频谱中的谐振峰出现的频率值与理论预测一致时,MEMS梁才是未粘附的,而其他情况下的MEMS梁都发生了部分或者全部的粘附,该结论与通过观察对应测试梁的表面形貌得出的结论是一致的：利用谐振法对不同干燥温度的MEMS梁的粘附问题进行了检测,实验结果表明,提高干燥温度有利于抑制粘附,这与相关的理论结果是一致的。以上内容的创新之处在于本文提出的谐振法具有无损和适用性广的优点,弥补了SEM法和干涉法无法准确检测宽MEMS梁的粘附问题的缺陷。(3)基于考虑了等效抗扭刚度的简支边界条件,建立了具有阶跃锚区的双端梁的振动模型,并推导了该振动模型的谐振频率和振型函数的理论表达式；利用该振动模型分析了杨氏模量和支撑梁的厚度对阶跃锚区双端梁谐振频率的影响,分析结果表明,随着杨氏模量和支撑梁的厚度的减小,阶跃锚区双端梁的谐振频率也会随之减小；利用ANSYS软件对阶跃锚区双端梁进行了有限元仿真,该仿真结果与本文模型的预测结果的对比表明,在梁长大于200μm时,本文中的振动模型得到的谐振频率的预测值和有限元仿真得到的值之间的误差要小于5%。以上内容的创新之处在于,本文中的振动模型相比固支锚区的模型更有效的描述了阶跃锚区双端梁的谐振特性。(4)为了方便残余应力的测量,设计了四向微旋转梁残余应力测量结构,利用ANSYS软件对四向微旋转梁残余应力测量结构进行了优化设计,并基于GaAs MMIC工艺制备了四向微旋转梁残余应力测量结构；实验测试结果表明,在GaAs MMIC工艺中,残余应力对MEMS梁的屈曲的影响很小。以上内容的创新之处在于,相比于传统的微旋转梁残余应力测量结构,该四向微旋转梁残余应力测量结构不需要制作标尺来测量指针梁的偏转位移,而且测量也更方便。以上可重构MEMS微波功率耦合器的设计方法填补了国内基于GaAs MMIC工艺的微波MEMS器件的空白,具有潜在的应用价值。同时,其中关于实验方法与理论模型的研究论文已被MEMS领域重要学术期刊录用以及审稿,具有较高的学术价值。
[Abstract]:Microwave power couplers are widely used in military and civil microwave communication fields. The coupling degree of traditional microwave power couplers is fixed. So a reconfigurable MEMS microwave power coupler with variable coupling is proposed in this paper, and the simulation, design and preparation of the reconfigurable MEMS microwave power coupling are completed. Because of MEMS devices, the design and preparation of the reconfigurable microwave power coupler are completed. In addition, the dynamic MEMS beam structure is added, and the reliability problem caused by the micro effect has become the most difficult problem to be solved in the design of MEMS devices. In this paper, a series of studies on the reliability of MEMS beams are carried out in this paper. The main contents and innovation points of this paper are as follows: (1) based on the GaAs MMIC process, a kind of design is designed. The MEMS microwave power coupler is reconstructed. The central frequency of the coupler with HFSS optimization is 35GHz, and the two different coupling degrees of 7.989dB and 10.62dB can be realized at 35GHz. In the range of 30 to 40GHz, the coupler is less than -15dB under two states, and the innovation of the isolation degree greater than 15dB. is that the coupler is the coupler. A double end beam with a cantilever beam is designed to adjust the coupling. The coupler has the same size as the traditional double line directional coupler under the same performance. Compared with the other reconfigurable calamers in size, the coupler has the obvious advantage. (2) the original vibration spectrum of the MEMS beam is influenced by the adhesion. According to the experimental results of vibration experiments, three common vibration spectra corresponding adhesion states are summarized. Only when the frequency values of the resonant peaks appear in the vibration spectrum are consistent with the theoretical predictions, MEMS Liang Cai is unadhered, and the other MEMS beams occur in other cases. The conclusion is consistent with the conclusion obtained by observing the surface morphology of the corresponding test beam: the adhesion of MEMS beams with different drying temperatures is detected by the resonance method. The experimental results show that the increase of the drying temperature is beneficial to the inhibition of adhesion, which is in agreement with the relevant theoretical results. The innovation of the content is that the resonance method proposed in this paper has the advantages of nondestructive and wide application, which makes up for the defect that the SEM method and interference method can not accurately detect the adhesion problem of the wide MEMS beam. (3) based on the simple supported boundary condition considering the equivalent torsion stiffness, the vibration model of a double end beam with a step anchor area is established and the vibration of the vibration is derived. The theoretical expression of the resonant frequency and the mode function of the dynamic model is used to analyze the influence of the young's modulus and the thickness of the supporting beam on the resonant frequency of the double end beam in the step anchor area. The results show that the resonance frequency of the double end beam in the step anchor area decreases with the decrease of the young's modulus and the thickness of the supporting beam. The finite element simulation of the double end beam of the step anchor area is carried out by ANSYS software. The comparison of the simulation results and the prediction results of the model shows that the error difference between the predicted value of the resonant frequency and the value obtained by the finite element simulation in this paper is less than the innovation of the content above 5%. when the beam length is more than 200 u m. The vibration model in this paper is more effective than the fixed anchor area model to describe the resonant characteristics of the double end beam in the step anchor area. (4) in order to facilitate the measurement of the residual stress, the residual stress measurement structure of the four direction micro rotating beam is designed. The ANSYS software is used to optimize the residual stress measurement structure of the four direction micro rotating beam, and based on the GaAs MMI The residual stress measurement structure of the four direction micro rotating beam is prepared by the C process. The experimental test results show that in the GaAs MMIC process, the residual stress has little effect on the buckling of the MEMS beam. The innovation of the above content is that the residual stress measurement structure of the four direction micro rotating beam is not needed compared to the traditional residual stress measurement structure of the traditional micro rotating beam. A ruler is made to measure the deflection displacement of the pointer beam, and the measurement is more convenient. The design method of the reconfigurable MEMS microwave power coupler has filled the blank of the microwave MEMS device based on the GaAs MMIC process in China, and it has potential application value. At the same time, the research papers about the experimental method and the theoretical model have been reproduced in the MEMS field. It is of high academic value to employ and review academic journals.

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN622

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