纳米操作系统的研究现状与关键技术

纳米操作是用于研究纳米材料、结构和装置的性质特征的基本技术,也是纳米构筑单元准备、纳米设备装配的必备技术。目前典型的纳米操作系统有基于扫描探针显微镜的系统,基于电子显微镜的系统,基于光镊的系统及混合式系统。详细阐述了各类系统的特点和发展现状。分析了末端工具、显微成像、定位与驱动、操作策略等纳米操作系统中的关键技术,并对发展趋势进行了展望。     

SPM三维纳米级微定位的研究

介绍了一种三维纳米级微定位系统。该系统可用于各种扫描探针显微镜（ＳＰＭ）探针和样品的微定位,探针可在样品表面１０ｍｍ×１０ｍｍ区域内定位,重复定位精度小于１００ｎｍ,在高度方向,探针可 顺利地进入样品表面１０ｎｍ区域内。     

扫描探针显微镜在粗糙度、纳米尺寸、表面形貌观测方面的应用

扫描探针显微镜是近十几年来在表面特征表面形貌观测方面最重大的进展之一，是纳米测量学的基本工具，本文叙述了扫描探针显微镜的工作原理、检测模式及在观察检测纳米级的粗糙度、微小尺寸、表面形貌方面的特点和方法，比较了原子力显微镜、常规的表面轮廓仪、干涉显微镜、扫描电子显微镜在表面特性、表面形貌观测方面的性能，着重介绍了扫描探针显微镜在这方面的应用和存在的问题。     

纳结构的连续激光复合微纳探针刻划加工

为了加工形貌稳定且尺寸尽可能小的纳结构,建立了一套连续激光复合微纳探针的加工系统,并研究了光纤探针导光的连续激光辐照微纳探针的近场增强效应以及该系统的加工性能。首先,根据表面等离子体激元理论仿真分析了激光辐照原子力显微镜(AFM)探针的近场增强因子,并研究了微纳探针的针尖温度场和针尖热膨胀。接着,搭建了基于光纤探针导光的连续激光复合微纳探针的纳结构加工系统。最后,对聚乙烯片状材料样品进行了纳结构加工。结果显示:加工得到的纳米点尺度为200nm左右;纳米线的尺度为30~40nm。结果表明:光纤探针导光连续激光复合微纳探针系统避免了复杂的空间光路结构,是一种成本低廉,结构简单的系统,能够实现纳结构的加工。     

基于图像聚焦定位的AFM自动逼近方法研究

原子力显微镜(AFM)是纳米科学技术领域中的常用工具。AFM扫描成像前需要手动或半自动操作步骤实现探针与样品逼近过程,自动化程度低、操作繁琐,探针容易受损。由此,提出了一种粗精结合的分段式自动定位方法。在粗定位阶段,采用自动聚焦定位方法,提出了一种最强边缘拉普拉斯算子均值算法,具有很强的抗噪性能,可以适应AFM长行程、不同纹理样品自动聚焦,以确定探针和样品的相对位置;精定位阶段,采用精确力反馈控制方法,当样品和探针作用力超过设定值时,探针在Z向纳米平台的带动下能够自动回退,使针尖得到有效保护。通过这两种方法的有效技术融合,可以实现探针-样品逼近过程的自动化操作,提高AFM的易用性和使用效率。     

大范围扫描的高精度三维数显镜体的设计

介绍了一种新型扫描探针显微镜镜体的设计,该镜体的扫描工作平台可以在3个方向以每步10nm的精度移动,它突破了扫描探针显微镜中压电陶瓷对扫描范围的限制,采用非压电陶瓷机械传动装置实现了大范围扫描.该设计采用逐级定位扫描放大技术将纳米测量与纳米加工范围延伸到25mm×25mm,甚至更大,镜体设计已经获得国家实用新型专利(ZL02221502.6).将该镜体应用在STM和AFM上,实现了对样品的大范围扫描检测,并保证了测量的高精度.     

基于光点偏转方法的原子力显微镜的研制

讨论了光点偏转方法检测微小位移的原理，建立了相应的光电检测系统，用于检测微悬臂（针尖）的微位移，并在此基础上研制了纳米级分辨率的原子力显微镜。仪器最大扫描范围可达2×2μm2。文中给出了部分样品的测试结果。     

基于SPM的纳米加工技术研究

扫描探针显微镜(SPM)纳米加工技术是当前非常活跃的纳米加工研究领域,其研究成果有可能成为微纳米器件制作的主要方法。论文主要介绍了单原子操纵、阳极氧化法,以及机械刻蚀加工等SPM纳米加工方法的机理、特点及研究进展动向。     

基于SPM的纳米加工技术研究

扫描探针显微镜（SPM）纳米加工技术是当前非常活跃的纳米加工研究领域,其研究成果有可能成为微纳米器件制作的主要方法。论文主要介绍了单原子操纵、阳极氧化法,以及机械刻蚀加工等SPM纳米加工方法的机理、特点及研究进展动向。     

应用聚焦离子束/电子束技术的碳纳米管探针制备工艺研究

提出利用电子束诱导铂沉积和聚焦离子束铣削技术,实现碳纳米管原子力显微镜探针针尖的制备和结构优化研究。结合高分辨率扫描电子显微镜观测和纳米操纵仪,利用电子束诱导铂沉积实现碳纳米管固定到普通原子力显微镜探针末端,可实现直径小于10nm的纳米管探针制备。提出基于聚焦离子束铣削和照射技术实现对纳米管针尖的长度、角度的精确调控优化,纳米管探针的角度调控精度优于1°。     

基于SPM的纳米加工技术研究进展

扫描探针显微镜(SPM)使人们不仅可以观察到物质表面的微观形貌,还可以在微纳米尺度上对样品表面进行加工,这种方法有可能成为未来微纳米器件的主要制作方法,成为推动人类科学和技术发展的新动力。主要介绍基于SPM的三种纳米加工方法:单原子操纵法、阳极氧化法和机械刻蚀法。详细阐述了各自的原理、特点及发展状况,并指出阳极氧化法是目前最有可能应用在实际生产制造中的加工方法,而机械刻蚀法则不仅可以作为纳米加工的手段,还可以应用于纳米加工机理方面的研究。     

Probing highly confined optical fields in the focal region of a high NA parabolic mirror with subwavelength spatial resolution

Parabolic mirrors with a high numerical aperture can be conveniently used to produce highly confined optical fields in the focal region. Furthermore, these fields can have interesting polarization behaviour due to the high numerical aperture. In particular, if the mirror is illuminated with a size matched radially polarized or azimuthally polarized doughnut mode, the electric field has in the focal region almost exclusively a longitudinal or a transverse polarization component. Such field distributions are interesting for applications in confocal or near‐field optical microscopy. Here we present experimental results where we have probed some of these field distributions by raster scanning a fine gold tip in nanometer steps through the focal region and detecting the scattered light intensity. The measured intensity patterns are compared with corresponding vector‐field calculations.     

Vibration assisted wire electrochemical micro machining of array micro tools

Micro structures and components are widely used in modern industries, and micro machining has therefore become a popular research topic. As micro tools are essential in micro machining, wire electrochemical micro machining is introduced in the fabrication of micro tools in this paper, and micro square column tool arrays are fabricated using wire cathodes by two steps. In order to improve the machining efficiency and quality, an electrode vibration technique is used, and the effects of bubble behaviour on slit width homogeneity and edge radius are studied through simulations of the electric field. The influences of various machining parameters such as vibration conditions, electrical properties, electrolyte concentration and feedrate on the standard deviation of the slit width and on the value of the edge radius are investigated. In addition, the micro dimple array is fabricated using electrochemical micro machining by employing the micro square column tool array as the cathode.     

Experimental research on effects of process parameters on servo scanning 3D micro electrical discharge machining

Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials.In 3D SSMEDM process,the axial wear of tool electrode can be compensated automatically by servo-keeping discharge gap,instead of the traditional methods that depend on experiential models or intermittent compensation.However,the effects of process parameters on 3D SSMEDM have not been reported up until now.In this study,the emphasis is laid on the effects of pulse duration,peak current,machining polarity,track style,track overlap,and scanning velocity on the 3D SSMEDM performances of machining efficiency,processing status,and surface accuracy.A series of experiments were carried out by machining a micro-rectangle cavity (900 μm×600 μm) on doped silicon.The experimental results were obtained as follows.Peak current plays a main role in machining efficiency and surface accuracy.Pulse duration affects obviously the stability of discharge state.The material removal rate of cathode processing is about 3/5 of that of anode processing.Compared with direction-parallel path,contour-parallel path is better in counteracting the lateral wear of tool electrode end.Scanning velocity should be selected moderately to avoid electric arc and short.Track overlap should be slightly less than the radius of tool electrode.In addition,a typical 3D micro structure of eye shape was machined based on the optimized process parameters.These results are beneficial to improve machining stability,accuracy,and efficiency in 3D SSMEDM.     

Improvement of Local Surface Quality by Using Single Abrasive Abrasion Process

AFM-based wear process actually is single abrasive abrasion process. It is widely employed in the surface micro/nano machining for fabrication of structures at the nanometer scale exhibiting high removing ability of nanometer scale materials. In this study, application of AFM-based single abrasive abrasion process in the local surface quality (surface roughness) improvement was studied. Merged holes were fabricated using an AFM diamond tip with different wear parameters on the surface of germanium (Ge) machined by conventional ultra-precision diamond turning. Results showed that cracks left by diamond turning can be removed and the local surface quality can be improved. Also effects of the wear parameters on the surface roughness were investigated. The optimized parameters of the abrasion process for improving the surface quality were provided. It is verified that AFM-based single abrasive abrasion process is a novel approach to modify or repair local surface on the surface of parts manufactured by other methods.     

Recent researches in micro electrical machining

The demand for micro parts and moulds has been increasing in various fields. Among the various micro machining technologies, micro electrical machining is one of the most widely used because it can be applied for conductive or nonconductive materials. This paper discusses the recent studies that explore many ways to improve micro electrical machining performance. Many researchers proposed ways to improve productivity and accuracy through experimental or analytical studies. The improved-performance trends of micro electrical machining are expected to continue thanks to the miniaturization of manufactured goods in a high-tech industry.     

Design and characterization of a PZT driven micromachining tool based on single-point tool tip geometry

This paper presents the design and characterization of a piezoelectric tube scanner (PZT) driven micromachining tool that is based on single-point tool tip geometries. The cutting module is made of a diamond stylus, which is known as the hardest material available. Therefore, this tool can be used to machine a wide range of materials ranging from polymers, through metals to glass. The microscopic cutting motion is achieved by using a piezo tube scanner as an actuator. The tool tip is attached to the free end of the PZT while the other end is firmly held stationary. By applying sinusoidal waveforms with different phase angles to the x and y electrodes of the PZT, the micro orbital motion of the diamond tip can be generated for machining purposes. This paper details the design of the tool and reports on its dynamic behavior in both short- and long-term experiments.     

Vibration assisted electrochemical micromachining of high aspect ratio micro features

The most used processes for generation of high aspect ratio microchannels are Nd: YAG laser technology on silica substrate and ultra violate lithography (UV-LIGA) process on metals. There are a few micromachining technologies such as micro mechanical milling, micro electro discharge machining (EDM) and electrochemical micromachining (EMM) for production of high-aspect-ratio micro features on highly stressed and anticorrosive metal like stainless steel. This paper discusses the micro fabrication of high aspect ratio micro features at the intended location on high strength stainless steel sheet of very small thickness to high thickness with highest average aspect ratio 14.33 achieved during microchannel generation by EMM with the help of coated microtool. Mathematical model relating aspect ratio with various parameters and machining conditions is derived to explore the ways to increase the aspect ratio of micro features. Experimental investigations were carried out to know the effect of vibration of microtool, frequency of pulsed voltage, microtool tip shape, thickness of work piece and non-conducting layer coated microtool on high aspect ratio micro features. Vibration of microtool with very small amplitude improved the stability of micromachining due to improved flow of electrolyte.     

Analytical and experimental study on the integration of ultrasonically vibrated tool into the micro electro-chemical discharge drilling

Electrochemical discharge machining (ECDM) is a non-traditional machining process which is used to create micro-features on non-conductive materials. Micro holes and micro channels are the most interested features that have been fabricated by researchers. In recent years, some technical augmentations have been added to the ECDM process to achieve a more efficient machining process, but the employment of each augmentation in the most efficient way is not subjected. In this research, ultrasonic vibration is concentrated on the tool tip which directly and continuously effects on the machining zone and avoids global undesirable effects. For this purpose, modal analysis is used to design a special configuration which achieves the maximum amplitude of vibration in the tool tip. Also, an analytical model is presented for both of the electro-chemical discharge machining (ECDM) and ultrasonic assisted electro-chemical discharge machining (UAECDM) to study the effect of ultrasonic vibration on the thickness of gas film. Practical gas film thickness, machining speed, entrance overcut and tapering zone are studied for both of the ECDM and UAECDM to comprehensive understanding the effect of integration of ultrasonic vibration into the traditional ECDM process. Captures of gas film in different condition confirmed that ultrasonic vibration has reduced the thickness of gas film. Same behavior was achieved by employment of the analytical modeling. As a result, numerous small discharges were achieved which increased the material removal rate (MRR) and hole accuracy, simultaneously. Results showed that ultrasonic vibration can increase MRR up to 82%. Also, tapering zone and entrance overcut deviation as accuracy parameters improved 50% and 40%, respectively.     

A compact CCD‐monitored atomic force microscope with optical vision and improved performances

A novel CCD‐monitored atomic force microscope (AFM) with optical vision and improved performances has been developed. Compact optical paths are specifically devised for both tip‐sample microscopic monitoring and cantilever's deflection detecting with minimized volume and optimal light‐amplifying ratio. The ingeniously designed AFM probe with such optical paths enables quick and safe tip‐sample approaching, convenient and effective tip‐sample positioning, and high quality image scanning. An image stitching method is also developed to build a wider‐range AFM image under monitoring. Experiments show that this AFM system can offer real‐time optical vision for tip‐sample monitoring with wide visual field and/or high lateral optical resolution by simply switching the objective; meanwhile, it has the elegant performances of nanometer resolution, high stability, and high scan speed. Furthermore, it is capable of conducting wider‐range image measurement while keeping nanometer resolution. Microsc. Res. Tech. 76:931–935, 2013. © 2013 Wiley Periodicals, Inc.