低真空封装的新型变电容面积MEMS惯性传感器阶跃响应特性分析

一种新型变电容面积MEMS惯性传感器与传统的梳齿电容传感器相比,具有对梳齿电容不平行敏感度低,可加测试电压高等优点。通过对该传感器在低真空封装条件下的惯性阶跃响应特性分析,着重研究了不同梳齿电容倾斜角度对该传感器的阶跃惯性信号响应的影响,以及不同倾斜角度梳齿的位移响应和测试电压、空气真空度的关系,并把该结果和梳齿结构的情况进行比较。结果表明,工艺因素对变电容面积MEMS惯性传感器在低真空封装下的阶跃惯性响应影响很小;另外,该结构上可加的测试电压可以是梳齿电容结构上可加测试电压的近10倍,这有利于减小接口电路的噪声。以上分析论证了该新型传感器有利于降低器件的工艺要求和提高传感器的分辨率。     

梳齿的不平行对电容式微机械传感器阶跃信号响应的影响

分析了梳齿电容式传感器在三种电容驱动方式下,梳齿电容极板的不平行对传感器受到阶跃加速度信号作用时可靠工作条件的影响。得到了梳齿倾斜效应对传感器阶跃加速度响应影响的分析模型。结果表明梳齿电容在同样的电压驱动下,若电容极板的倾斜角变到0.5°时,对于单边电容结构、双边电容结构和有力反馈的双边电容结构,传感器能够承受的临界阶跃加速度分别变为电容极板完全平行时的0.34、0.44、0.52。并针对DRIE工艺刻蚀梳齿的原理,讨论了改进梳齿不平行的方法。     

低热机械噪声MEMS加速度计设计

介绍了一种能够在大气条件下具备低噪声、高灵敏度特性的MEMS加速度计设计、制作与测试.器件采用梳齿电容检测方法,利用MEMS体硅加工工艺,实现了210对梳齿的加速度计制作.该加速度计不需要真空封装和阻尼孔就能实现低热机械噪声特性,其理论热机械噪声为0.018μg/√Hz.加速度计芯片在大气封装和无阻尼孔情况下Q值高达4...     

基于微位移定位系统MEMS梳齿位移传感器的研究

MEMS硫齿位移传感器是一种基于MEMS技术电容理论的传感器,具有体积小、重量轻、性能稳定、功耗低和易于集成等特点.首先探讨了梳齿传感器的工作原理,随后介绍了使用梳齿传感器有效检测微动工作台位移的方法,并进行了结构失效和梳齿电极不平行失效的可靠性分析.通过采用这种传感器可以达到提高微位移定位平台系统的集成度、精度、分辨...     

用于器件级真空封装的MEMS加速度传感器的设计与制作

设计了一种可用于器件级真空封装的三明治电容式MEMS加速度传感器.该传感器被设计为四层硅结构,其中上下两层为固定电极,中间两层为硅-硅直接键合的双面梁-质量块结构的可动电极.利用自停止腐蚀工艺在中间质量块键合层上腐蚀出2个深入腔内的V型抽气槽,使得MEMS器件在后续的封装中能够实现内部真空.为防止V型抽气槽在划片中被水或硅渣堵塞,采用双面划片工艺.划片后,器件的总尺寸为6.8mm ×5.6mm ×1.72 mm,其中,敏感质量块尺寸为3.2mm×3.2mm ×0.86mm,检测电容间隙2.1 μm.对器件级真空封装后的MEMS加速度传感器进行了初步测试,结果表明:制作的传感器的谐振频率为861 Hz,品质因数Q为76,灵敏度为1.53 V/gn,C-V特性正常,氦气细漏＜1×10-9 atm-cm3/s,粗漏无气泡.     

倾斜梳齿的MEMS电容式加速度传感器自我标定特性研究

本论文研究MEMS电容式加速度传感器的自我标定方法,模拟机械振动台标定,提高标定效率和降低标定成本,并从理论上分析了DRIE工艺误差对传感器自我标定精度的影响。本文分析的传感器模型梳齿间距为4um,厚度80um,传感器自我标定以模拟幅值为1g的振动台标定为例,针对DRIE工艺加工的高深宽比梳齿电容存在正负侧壁倾斜角α的情况,分析了该倾斜角对梳齿式传感器自我标定的影响。分析结果表明：传感器工作在开环电路时,梳齿的倾斜对传感器自我标定影响明显,且随着倾斜角度的增大而增大。与梳齿完全平行时传感器的自我标定相比,倾斜角为±0.1°时,自我标定误差约为10%;倾斜角为0.5°时,自我标定误差约为27%;倾斜角为-0.5°时,极板发生吸合。表明传感器工作在开环电路时,梳齿的倾斜角对传感器的自我标定影响明显,而传感器工作在闭环电路时,梳齿的倾斜对自我标定的影响明显降低,当倾斜角小于±0.5°时,自我标定的误差小于0.6%,理论误差接近于激光干涉仪绝对标定法的误差(0.5%－1%),证明了自我标定方法的可行性。本文还分析了倾斜角影响自我标定精度的原因以及提出了开环自我标定时减小倾斜角误差的方法,并阐述了具体的修正步骤。     

地震勘探用三维MEMS加速度传感器的研究

以MEMS加速度传感器为基础的新型数字地震检波器是地震勘探所用仪器的发展方向之一。介绍了一种三维MEMS加速度检波器结构,这有别于传统三分量MEMS传感器通过用3只MEMS加速度传感器按正交直角组装。并通过PSpice软件对其进行了整体仿真,仿真结果表明其阶跃响应和正弦响应基本和理论分析的结果吻合。     

基于永磁薄膜的MEMS磁传感器设计与制作

提出了一种基于永磁薄膜的新型MEMS磁传感器,磁传感器由MEMS扭摆、CoNiMnP永磁薄膜和差分检测电容等部分组成。分析了磁传感器的磁敏感原理和电容检测原理,提出了器件的结构参数并对器件进行了模态仿真。利用MEMS加工技术成功制作了MEMS磁传感器样品,并进行了测试。测试结果表明:得到的MEMS磁传感器的电容灵敏度可达到27.7 fF/mT,且具有良好的线性度。根据现有的微小电容检测技术,传感器的磁场分辨率可达到36 nT。     

圆片级低真空封装的MEMS压电振动能量收集器结构设计

MEMS低真空封装技术能为MEMS器件的可动部分提供低阻尼环境,降低能量损耗,有效提高器件的能量转换效率,具有重要的研究意义和应用前景,是MEMS技术的研究热点和难点。为了进一步提高MEMS压电振动能量收集器的输出性能,提出了圆片级低真空封装的共质量块MEMS压电悬臂梁阵列振动能量收集器新结构,通过有限元分析方法对器件结构参数进行了优化设计,在优化结构参数下仿真器件输出性能：在610 Hz、2 gn加速度下,器件的输出电压为8.88 V,输出功率为1220μW,能满足实际应用需求;根据器件结构设计了加工工艺流程,对低真空封装结构的实现和封装工艺探索具有重要意义。     

中国微米纳米-----梳齿式加速度传感器敏感结构等效并联电阻对输出的影响分析

梳齿式加速度传感器敏感结构间感应电容的测量会受到结构间等效电路参数的影响。多层瓷片电容的结构与梳齿式加速度传感器敏感结构类似。本文类比多层瓷片电容中等效电路参数的研究,分析了梳齿式加速度传感器敏感结构间等效电路参数对感应电容测试结果产生的影响。     

Metallic micro displacement capacitive sensor fabricated by laser micromachining technology

This paper presents design, fabrication and performance testing results of the micro displacement capacitive microsensor fabricated by femtosecond laser machining technology. The microsensor having overall dimensions of 1,275 (W)×1,153 (L) μm consisted of 20 pairs of comb fingers of 24 (W)×300 (L) μm with a gap between the fingers of 6 μm, suspension springs, inertial mass and support anchors. The sensor structure was fabricated from a 25 μm thick tungsten foil. The fabricated microsensor was able to deliver 230 fF capacitance variations for measured displacements up to 25 μm. The results on the performance testing and geometry evaluation under pins the laser micromachining technology as an effective tool to fabricate miniature functional components and mechanisms. The developed microsensor can be used for micro/nano scale displacement measurements in MEMS applications.     

不同检测电容结构对MEMS电容传感器性能的影响分析

改进传感器检测电容几何结构能有效改善传感器的性能。本文对梳齿电极结构、栅形电极结构及梳栅电极结构检测电容的性能特点进行分析比较,重点分析了振子质量、空气阻尼、系统阻尼系数比以及灵敏度等特性,得出在相同的外轮廓尺寸、支撑梁、振子厚度以及振子到衬底的距离的条件下,栅形结构传感器的振子质量最大,空气阻尼最小,适合制作高分辨率的传感器;在大气下,梳齿结构灵敏度增加的同时空气阻尼力也会增加,且振子质量较小,适合制作高灵敏度,低分辨率传感器结构;梳栅结构的特点居于两者之间,适合制作需要兼顾分辨率和灵敏度的传感器。通过实例计算,证明了该结果。     

Reliability design of thermally actuated MEMS switches based on V-shape beams

This paper presents the design and fabrication of the thermally actuated MEMS switches based on out-of-plane V-beams. The purpose of this research is to analyze the mechanical response of a V-thermal actuator fabricated from aluminum in order to improve the accuracy in response and to increase the switch lifetime. The actuation of this kind of switches is based on the thermal displacement of the mobile electrode under thermal load that is generated when the actuation voltage is applied. It can be used either as a capacitive switch or as a metal-to-metal one. The displacement of the mobile electrode for a given temperature is analytically calculated and validated both numerically and experimentally. Experimental investigations are performed on a macro-scale sample using a 3D digital image correlation measuring system, a heating source and a thermal camera for temperature monitoring. The first fabrication steps of the MEMS switch based on the V-beam thermal actuator are presented. The out-of-plane V-beams thermal MEMS switches can be monolithically integrated in RF applications.

     

高精度电容位移传感器设计

采用多极板电容结构设计了电容位移传感器,由振荡器电路、二极管环形检波电路、低通滤波器、放大器等组成测试系统,测试了此传感器的位移-输出电压特性,并对测试数据进行回归分析.发现该传感器具有结构简单、灵敏度高、非线性误差小等特点,在位移等非电量测量方面具有较好的应用前景.     

A resonant microstructure tunability analysis for an out-of-plane capacitive detection MEMS magnetometer

In this paper, the method of tuning the resonant frequency of a micro-resonant clamped–clamped beam has been successfully applied to a MEMS capacitive magnetometer. The resonant structure frequency, which presents the vital component of the sensor, was tuned by applying a bias voltage between the interdigitated capacitive comb-fingers in order to control its spring constant. It has been proved that an applied DC voltage increases the structure stiffness and as a result the resonance frequency to higher values, especially for low motion magnitude. The shifting causes were described through an accurate analytic analysis using the generated electrostatic force between movable and fixed combs, and thereafter have been proved by characterization. The measured resonance frequency of the clamped–clamped beam structure was changed by up to 38 % from the original value (around 18.2 kHz) when a bias voltage of 52 V was applied. Tuning the resonant frequency of the resonating structure has many advantages for the magnetometer since it can serve as a feedback mechanism for error compensation.

     

Active gap reduction in comb drive of three axes capacitive micro accelerometer for enhancing sense capacitance and sensitivity

The performance of micro-machined sensors is primarily determined via the sensitivity of sensing electrode to displacement. This paper presents the design, modelling, optimization and fabrication of an active gap reduction mechanism used on a conventional comb drive to enhance the capacitance in a three axes capacitive micro accelerometer. The design parameters of the active gap reduced comb drive (AGRCD) are optimized for best performance. The finite element analysis of the AGRCD is performed for design verification. The modeling and simulation results demonstrated a 534 % increase in sensitivity of the three axes capacitive micro accelerometer. The three axes capacitive micro accelerometer with AGRCD is fabricated using a commercially available standard metal-multi user MEMS processes.     

Modeling flexural plate wave devices

A lumped-parameter model is derived for flexural plate wave (FPW) devices which are rectangular plates or diaphragms with structural layers, a piezoelectric layer, and with interdigitated conducting combs for driving and sensing. This configuration is often used in micromechanical chemical sensors. The model is based an a closed-form solution of a resonating beam; however, the results are applicable to plates supported on four edges. The model gives a voltage or charge output from the sense combs as a function of voltage applied to the drive combs. The analysis predicts the response of the multiple plate modes to axial tensions and to comb finger dimensions and position relative to the diaphragm eigenfunctions. These models are much more detailed than those described in the literature on acoustic chemical sensors and are difficult to obtain by finite-element solutions. Frequency responses of FPW devices constructed from silicon with deposited aluminum nitride as the piezoelectric compared well with analytic results. The effects of boundary conditions on the plate's lateral edges are discussed in both the analysis and testing     

用于硅基氮化镓可调微镜的静电梳齿型微驱动器设计

提出并设计了一种用于硅基氮化镓(GaN)可调微镜的静电梳齿型微驱动器.利用有限元软件建立了该器件的几何结构模型,对器件的结构进行了仿真优化.此外,采用微机电系统(MEMS)加工工艺,制作出了用于硅基氮化镓可调微镜的梳齿型微驱动器,并对其驱动特性进行测试.测试结果表明:所制作的微驱动器的位移随着电压的变化呈二次方关系,与仿真结果基本一致.当加载驱动电压为200 V时,微驱动器的驱动位移可达到1.08 μm.     

Pull-In Analysis of Torsional Scanners Actuated by Electrostatic Vertical Combdrives

This paper presents pull-in analysis of torsional MEMS scanners actuated by electrostatic vertical combdrives with general comb gap arrangements and cross sections. The analysis is based on a 2-DOF actuator with a single voltage control. Three failure modes of the scanners are identified as in-plane twist, transversal motion, and out-of-plane twist. For each failure mode, analytical expressions of pull-in deflection are obtained by applying 2D analytical capacitance models to the derived pull-in equations. From these, the dominant pull-in mechanism is shown to be in-plane twist for scanners with high-aspect-ratio torsional springs. The analytical calculations for both symmetric and asymmetric capacitances are shown to be in good agreement with simulation results. The optimum scanner design is achieved when the pull-in deflection matches the capacitance maximum angle. The condition can be expressed in terms of the ratio of the comb thickness to the comb gap, which is smaller than the typical aspect ratio of deep reactive ion etching. The optimum tradeoff between the maximum deflection angle and the number of movable combs is achieved by adjusting the overlap of the movable and fixed combs and the distance of the comb sets from the axis of the rotation.