用于微装配的三维微力传感器的研究

采用硅基应变片设计了一种可用于精密微装配作业过程,检测x、y、z方向微接触力的三维微力传感器;经微小改动后,该传感器可成为五维微力传感器。分析了力传感器测量原理,建立其测量模型,并设计了传感器信号放大电路。测试了微力传感器的性能指标,在x、y、z3个方向的微力测量分辨率为0.001 N,测量精度可达0.005 N,测量范围为-0.5~ 0.5 N。最后设计了微装配作业控制系统,并利用该传感器实现力位移混合控制,顺利完成了180μm微型轴与200μm微型孔间的精密微装配实验研究。     

用于微摩擦测试的微力传感器及其制作

微构件表面的摩擦状况和磨损机理与宏观构件有较大的区别，需一种能够测量微米尺度样品摩擦特性的专用仪器。给出了一种新型硅微力传感器的设计原理、结构、制作工艺及其弱信号采集方法。静态性能测试结果表明，传感器最大输出电压2000μV，重复性约为1．3％，灵敏度约为65V／N，分辨率为46μN，总精度为2．3％，基本上满足了微摩擦测试的需要。实验及计算表明，通过优化微力传感器的结构，改进芯片的封装，可以大大减少其体积，并提高其各项性能指标。     

面向三维组装的微纳平台设计与研究

针对20~40μm尺寸范围的微对象夹持需求,设计了一种压电驱动的微组装夹持器平台。使用有限元分析优化了夹持器的结构参数。该平台可以实现两指与三指操作模式的转换及对多种微对象的柔性操作。该文绘制了实验平台中压电陶瓷的驱动电压与执行末端位移的关系,单指的驱动范围0~41μm。压电陶瓷对该平台的输出位移分辨率达到了0.5μm/V。以直径20μm、40μm两种尺寸的硼硅酸盐玻璃球为操作对象,完成了夹持、释放及三维模型组装实验。     

两级位移放大微夹持器的研究

微夹持器是完成微操作、微装配作业任务的重要工具,其体积、质量、张合量、微夹持力等是微夹持器设计过程中的重要指标。利用压电陶瓷作为微驱动元件设计了一种具有两级位移放大的微夹持器,并采用有限元软件对其进行张合量、微夹持力的分析。经实验测试,验证了所设计的微夹持器的合理性和实用性。     

面向扑翼微飞行器的扭矩传感器研究

由于仿昆虫扑翼微飞行器需要在小范围内传输扭矩,且扭矩数值较小,一般的扭矩传感器或力传感器在其动态范围内均难以达到测量精度的要求。为了解决这一问题,提出了一种新型单轴扭矩传感器的设计方案,并完成了实际的制造和测试。该扭矩传感器的主体为殷钢材料,由激光加工制作而成,利用电容式位移传感器测量主轴旋转时目标板的位移,从而建立输出电压与施加扭矩之间的对应关系。传感器带宽和分辨率与微飞行器飞行实验的标准相匹配,同时对离轴负载保持不敏感。经实验测定,该单轴扭矩传感器的带宽为1.1kHz,测量范围为±260.8μNm,分辨率为0.013μNm,可以满足微飞行器扭矩的测量需求。     

基于探针形式的三维硅微力传感器

为满足三维微力测量的需求,以MEMS体硅压阻工艺技术为基础,研制了一种基于微探针形式,具有μN级三维微力测量和传感能力的半导体压阻式三维微力硅微集成传感器。传感器采用相互迟滞的4个单端固支硅悬臂梁,支撑中间的与微力学探针结合在一起的质量悬块的结构形式,在4mm×4mm的硅基半导体芯片上用MEMS体硅工艺集成而成。通过ANSYS数值仿真的方法分析了三维硅微力传感器结构的应力特点,解决了三维微力之间的相互干扰问题,并对传感器性能进行了测试。结果表明,其X、Z方向的线性灵敏度分别为0.1682、0.0106mV/μN,最大非线性度分别为0.19%FS和1.1%FS。该传感器具有高灵敏度、高可靠性、小体积、低成本等特点。     

一种基于厚膜陶瓷电容的微位移传感器

为深入研究微纳米环境中物体的受力与运动状态,实现微纳米环境下的位置感知与位移操作,建立纳米尺度下位移、力检测的理论方法,研制了一种基于厚膜陶瓷电容的微位移传感器。通过采用厚膜混合集成工艺将信号处理电路与厚膜电容芯片一体化集成,即用厚膜电路替代PCB电路板,以达到降低由于温度效应和寄生电容等导致的非线性误差,提高传感器的分辨率和稳定性的效果。传感器性能标定实验结果表明,0~1 000nm量程范围内位移检测分辨率优于2nm,传感器稳定性得到显著提高,能够用于检测纳米级微小位移变化量。此外,还从材料物理属性和电路优化设计等方面分析了一体化集成的厚膜电路相对于PCB电路板的优越性。     

基于FBG的悬臂梁式微力与微位移传感单元北大核心CSCD

设计了一种基于光纤布拉格光栅(fiber Bragg grating,FBG)的微力与微位移双物理量传感单元,采用矩形悬臂梁型弹性体结构以及两片FBG布片方式,提高了力和位移灵敏度,实现了温度补偿,位移灵敏度可通过改变悬臂梁的固定位置和长度进行调整。对传感单元的性能进行了理论分析和实验验证,结果表明:在0~1.2 N测量范围内,力实验灵敏度为889 pm/N,理论和实验的平均相对误差为6.6%,力分辨力为1.1 mN,位移灵敏度随着悬臂梁长度L的增大而减小,位移灵敏度在L为149 mm时为60.7 pm/mm,在L为99 mm时为200.3 pm/mm,位移分辨力为5μm,传感单元的线性度均达0.999以上,保持了优良的线性,可满足不同量程的微力和微位移应用场合。     

基于微环辅助的M-Z温度传感器

针对普通马赫-曾德尔(M-Z)滤波器为了获得良好的滤波性能需要mm量级的臂长差的问题,文章提出了一种基于微环辅助M-Z滤波原理的温度传感器,其具有μm量级的尺寸。在M-Z滤波器的一个臂上耦合一个液体微环腔,利用微流控技术将一些温敏液体注入腔内,通过分析传感器的输出光谱,可以检测到温度的变化。实验结果表明,该传感器具有良好的滤波性能及温度分辨能力,消光比>10 dB,3 dB带宽<1 nm,温度检测分辨率可达到0.1℃。此外,通过改变微环中液体的种类,可以调节传感器的温度检测范围。     

基于光学聚焦方法的热驱动微执行器位移测量

随着微机电系统（MEMS）设计日趋成熟,度量问题越来越成为微系统技术中的热点。使用改进的拉普拉斯求和方法（SML）和深度估计法来测量热度驱动微夹持器末端的弯曲程度。实验中,使用了10幅在42℃时微夹持器的水下工作图像来验证这种光学聚焦方法,结果证明使用光学聚焦方法可以测量出作为驱动器反馈输入的末端弯曲大小,实现对驱动器运动的精确控制。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.