基于AFM的光盘形貌研究

介绍了原子力显微镜(AFM)的原理及特点。用AFM对光盘上记录信息用的凹坑结构进行了三维检测,并对测量结果进行了分析。结论表明AFM在光盘质量检测过程中具有独特的优势。     

原子力显微镜(AFM)在光盘检测及其质量控制中的应用

综述了原子力显微镜(AFM)在光盘质量检测中的应用.AFM能够在nm尺度上直接对光盘及其模板上的信息位几何结构的特征尺寸及其误差进行三维测量,从而可以建立生产工艺参数和信息位几何结构之间、信息位几何结构和盘片电气性能之间的关系,进而找出影响光盘质量的直接原因.用AFM进行光盘质量检测主要有三方面：盘片和模板表面的定性观测;信息位几何结构的半定量分析;信息位特征尺寸的统计分析.定性观测和半定量分析可以对盘片播放的高误差率、凹坑形态和块出错率、凸台形态及其表面粗糙度等参数进行有针对性的检测;而信息位特征尺寸的统计分析则可以对信息位几何结构的关键参数进行面向生产过程的统计分析.所得结论表明AFM在光盘质量检测过程中具有独特的优势.     

一种高精度多功能双用原子力显微镜技术及应用

主要研究了一种基于高精度IPC-205B型扫描隧道显微镜(STM)的新型高精度多功能双用原子力显微镜(AFM)技术及其应用.阐述该原子力显微镜的工作原理、组成及应用,详细介绍了该AFM镜体的独特结构和新型微悬臂的制作及其检测方法.该AFM采用简单适用的新型微悬臂.并利用STM检测微悬臂的起伏,通过四维机械驱动和双压电陶瓷扫描,有效提高了扫描精度,扩大了扫描范围.该机型集AFM和STM功能为一体,其中STM可以单独使用.该机型检测精度可达:横向0.1 nm,纵向0.01 nm.并用该样机进行了样品表面形貌和隧道谱的实验研究.     

AFM在煤体微结构研究中的应用

介绍了煤表面的微结构特点和煤表面的各种检测方法及其特点.经过比较,选用原子力显微镜(AFM)对煤体表面进行了三维检测,利用CSPM-2000 lmager软件对扫描得到的图像进行了颗粒度分析,并提出了一种计算煤表面突出颗粒与孔隙所占比例的方法.结论表明AFM在煤体微结构检测过程中具有独特的优势.     

利用原子力显微技术对神经胶质细胞超微结构及其相互间的纳米连接结构的观察

本研究利用原子力显微技术（AFM）观察原代培养的神经胶质细胞及其相互间的纳米连接结构。选择生长良好的神经胶质细胞用戊二醛固定30分钟,固定于AFM基底上进行扫描成像,用AFM脱机软件（SPM OFFLINE 2．20）进行检测。观察到胶质细胞平铺于培养皿的底部,胞体形状不规则,表面较扁平。突起丰富,但没有极性,无轴突树突之分,还观察到两胶质细胞间存在长程纤维管状连接结构。     

原子力显微镜在细胞生物学中应用的现状

原子力显微镜(AFM)是近十几年来表面成像技术最重要的进展之一.AFM具有原子级分辨率,它的产生和发展为细胞生物学研究提供了一种有效的工具.本文介绍原子力显微镜在细胞生物学中应用的现状,包括细胞固定,细胞成像,力检测及细胞操纵,并对原子力显微镜技术的发展进行展望.     

原子力显微镜传感器的微机械加工技术的研究

分析了现有的AFM力传感器的工艺特点及问题。在此基础上研究用KOH溶液两步法P+自停止腐蚀制作厚度精确可控的单晶硅悬臂梁;以SiO2为掩模,SF6刻蚀硅,用RIE与各向同性湿法化学腐蚀相结合使悬臂梁探针一次成形和用湿法腐蚀锐化探针,针尖半径约50nm.制定了适于批量生产的AFM力传感器加工工艺。     

基于AFM的煤体微结构研究

比较了扫描电子显微镜和原子力显微镜的原理及特点。得出了AFM的独特优势。用AFM对煤的表面微形貌进行了三维测量，观测到煤中的颗粒和气孔，气孔形状以圆形为主，其次有椭圆形，且边缘光滑，轮廓清晰，据AFM分析，平均气孔孔径为92.25nm，最小孔径10nm，最大孔径800nm。结论表明。用AFM可以观测到煤真实、精确的表面微形貌，为分析瓦斯分子在煤孔隙中的分布提供了一种研究和测量方法。     

气/液两用型原子力显微镜及其应用研究

发展了一种气/液两用型原子力显微镜(AFM)系统,讨论了其工作原理,给出了优化的气/液两用型探头及扫描与反馈控制电路。利用该型AFM系统分别对大气环境下的硅片以及液体环境下的刀片和多孔氧化铝样品进行了扫描检测。实验结果表明,该型AFM系统在大气和液体环境中均可扫描获得理想的AFM图像,分辨力达到纳米量级,扫描范围可达4000nm×4000nm,可满足各种微纳米扫描测量的要求。     

基于AFM的微注射量检测装置设计

介绍了一种基于原子力显微镜(AFM)的微注射量检测的新方法,设计聚酯悬臂感应结构,利用原子力显微镜具有纳米级高度分辨率的特点,对聚酯悬臂在注射微滴重力作用产生的挠度进行检测,达到微滴量检测的目的.通过改进检测装置隔震系统的阻尼器结构,抑制影响微滴检测过程的低频扰动因素.最后对30pl内的微注射量进行检测试验.     

Carbon nanotubes: a promising standard for quantitative evaluation of AFM tip apex geometry

The direct contact between tip and sample in atomic force microscopy (AFM) leads to demand for a quantitative knowledge of the AFM tip apex geometry in high-resolution AFM imaging and many other types of AFM applications like force measurements and surface roughness measurements. Given, the AFM tip apex may change continuously during measurements due to wear or during storage due to oxidation, it is very desirable to develop an easy and quick way for quantitative evaluation of AFM tip radius when necessary. In this study, we present an efficient method based on Zenhausern model (Scanning 14 (1992) 212) by measuring single-wall carbon nanotubes deposited on a flat substrate to reach this goal. Experimental results show the method can be used for routine quantitative evaluation of AFM tip apex geometry for tips with effective radii down to the nanometer scale.     

Study of the tip mass and interaction force effects on the frequency response and mode shapes of the AFM cantilever

The vibrational characteristics of an atomic force microscope (AFM) cantilever beam play a key role in dynamic mode of the atomic force microscope. As the oscillating AFM cantilever tip approaches the sample, the tip–sample interaction force influences the cantilever dynamics. In this paper, we present a detailed theoretical analysis of the frequency response and mode shape behavior of a cantilever beam in the dynamic mode subject to changes in the tip mass and the interaction regime between the AFM cantilever system and the sample. We consider a distributed parameter model for AFM and use Euler–Bernoulli method to derive an expression for AFM characteristics equation contains tip mass and interaction force terms. We study the frequency response of AFM cantilever under variations of interaction force between AFM tip and sample. Also, we investigate the effect of tip mass on the frequency response and also the quality factor and spring constant of each eigenmodes of AFM micro-cantilever. In addition, the mode shape analysis of AFM cantilever under variations of tip mass and interaction force is investigated. This will incorporate the presentation of explicit analytical expressions and numerical analysis. The results show that by considering the tip mass, the resonance frequencies of the cantilever are decreased. Also, the tip mass has a significant effect on the mode shape of the higher eigenmodes of the AFM cantilever. Moreover, tip mass affects the quality factor and spring constant of each modes.     

A large-sample atomic force microscope observing in both air and liquid

A large-sample atomic force microscope (AFM) that allows high resolution observation in both air and liquid has been developed. With a unique beam tracking method, laser beam is capable of reflecting off the same spot on the AFM cantilever throughout raster scan over the entire scan area, either operating in air or in liquid environment. Incorporating the stand-alone AFM probe unit with an automated large sample stage, wide-scan-range imaging can be realized with high resolution and slight distortion. In addition, an image stitching method is utilized to build a broad merged image with range up to millimeters while keeping nanometer order resolution. By using a large-volume liquid bath, large and massive sample can be observed in liquid with this AFM system. Several typical experiments have been carried out to demonstrate the imaging ability and stability of this AFM. Topographic structures of gold pattern on a glass substrate are scanned at two different places on the same specimen surface. The porosity of a sheet of filter paper is then characterized in both air and water. Finally, larger-area AFM image of anodic aluminum oxide template in oxalic acid is on spot obtained by merging several individually scanned images together. Experiments show that this AFM system can offer high resolution and wide range AFM images even for large samples with remarkable capabilities in various environments.     

Investigation of influence of gas atmosphere and pressure upon non-contact atomic force microscopy

Resonance measurements and atomic force microscopy (AFM) observations were carried out by the non-contact AFM operating in various gas atmospheres (hydrogen, helium, nitrogen and argon) over the range of pressures from 0.1 to 1.1 MPa. In each atmosphere, the resonance frequency of the AFM cantilever depended on the pressure of gases studied. The plots of the relative resonance frequency at a constant pressure vs. the gas density gave a straight line. It was found that the characteristic of the resonance frequency for the AFM cantilever were dependent on the density of the gas species. The resolution of the AFM was hardly influenced by the gas atmosphere under the present experimental conditions.     

Finite-element vibration analysis of tapping-mode atomic force microscopy in liquid

Investigation of morphology and mechanical properties of biological specimens using atomic force microscopy (AFM) often requires its operation in liquid environment. Due to the hydrodynamic force, the vibration of AFM cantilevers in liquid shows dramatically different dynamic characteristics from that in air. A good understanding of the dynamics of AFM cantilevers vibrating in liquid is needed for the interpretation of scanning images, selection of AFM operating conditions, and evaluation of sample's mechanical properties. In this study, a finite element (FE) model is used for frequency and transient response analysis of AFM cantilevers in tapping mode (TM) operated in air or liquid. Hydrodynamic force exerted by the fluid on AFM cantilevers is approximated by additional mass and hydrodynamic damping. The additional mass and hydrodynamic damping matrices corresponding to beam elements are derived. With this model, numerical simulations are performed for an AFM cantilever to obtain the frequency and transient responses of the cantilever in air and liquid. The comparison between our simulated results and the experimentally obtained ones shows good agreement. Based on the simulations, different characteristics of cantilever dynamics in air and liquid are discussed.     

原子力显微镜在蛋白质研究中的应用

AFM对于蛋白质的研究是一个极好的工具,它可以进行表面成像、分析蛋白质的大小和体积、测量蛋白质空间结构,表征蛋白质的结构与功能、了解分子间的相互作用等等。本文主要从AFM样品制备及其在蛋白质研究中的应用等几个方面进行了系统地阐述。     

Atomic force microscopy of freeze-fracture replicas of rat atrial tissue

Atomic force microscopy (AFM) has provided three-dimensional (3-D) surface images of many biological specimens at molecular resolution. In the absence of spectroscopic capability for AFM, it is often difficult to distinguish individual components if the specimen contains a population of mixed structures such as in a cellular membrane. In an effort to understand the AFM images better, a correlative study between AFM and the well-established technique of transmission electron microscopy (TEM) was performed. Freeze-fractured replicas of adult rat atrial tissue were examined by both TEM and AFM. The same replicas were analysed and the same details were identified, which allowed a critical comparison of surface topography by both techniques. AFM images of large-scale subcellular structures (nuclei, mitochondria, granules) correlated well with TEM images. AFM images of smaller features and surface textures appeared somewhat different from the TEM images. This presumably reflects the difference in the surface sensitivity of AFM versus TEM, as well as the nature of images in AFM (3-D surface contour) and TEM (2-D projection). AFM images also provided new information about the replica itself. Unlike TEM, it was possible to examine both sides of the replica with AFM; the resolution on one side was significantly greater compared with the other side. It was also possible to obtain quantitative height information which is not readily available with TEM.     

AFM针尖"突跳"研究

为了研究原子力显微镜（AFM）“突跳”现象的产生机理，基于经典弹性理论和Lennard-Jones势能定律建立了AFM针尖与样品纳米接触的弹性模型。给出了在AFM针尖逐渐趋近样品表面的过程中，AFM针尖与样品间的粘着力、样品表面的轮廓曲线和样品表面的变形量随AFM针尖与样品表面间距的变化规律。分析了AFM“突跳”现象的产生机理和影响因素。研究表明，AFM“突跳”现象主要是由样品表面在粘着引力的作用下产生拉伸变形并与AFM针尖“突跳”接触引起的。     

Dynamic analysis of tapping mode atomic force microscope (AFM) for critical dimension measurement

Transient dynamics of tapping mode atomic force microscope (AFM) for critical dimension measurement are analyzed. A simplified nonlinear model of AFM is presented to describe the forced vibration of the micro cantilever-tip system with consideration of both contact and non-contact transient behavior for critical dimension measurement. The governing motion equations of the AFM cantilever system are derived from the developed model. Based on the established dynamic model, motion state of the AFM cantilever system is calculated utilizing the method of averaging with the form of slow flow equations. Further analytical solutions are obtained to reveal the effects of critical parameters on the system dynamic performance. In addition, features of dynamic response of tapping mode AFM in critical dimension measurement are studied, where the effects of equivalent contact stiffness, quality factor and resonance frequency of cantilever on the system dynamic behavior are investigated. Contact behavior between the tip and sample is also analyzed and the frequency drift in contact phase is further explored. Influence of the interaction between the tip and sample on the subsequent non-contact phase is studied with regard to different parameters. The dependence of the minimum amplitude of tip displacement and maximum phase difference on the equivalent contact stiffness, quality factor and resonance frequency are investigated. This study brings further insights into the dynamic characteristics of tapping mode AFM for critical dimension measurement, and thus provides guidelines for the high fidelity tapping mode AFM scanning.     

Fabrication of ball-shaped atomic force microscope tips by ion-beam-induced deposition of platinum on multiwall carbon nanotubes

Ball-shaped atomic force microscope (AFM) tips (ball tips) are useful in AFM metrology, particularly in critical dimension AFM metrology and in micro-tribology. However, a systematic fabrication method for nano-scale ball tips has not been reported. We report that nano-scale ball tips can be fabricated by ion-beam-induced deposition (IBID) of Pt at the free end of multiwall carbon nanotubes that are attached to AFM tips. Scanning electron microscopy and transmission electron microscopy analyses were done on the Pt ball tips produced by IBID in this manner, using ranges of Ga ion beam conditions. The Pt ball tips produced consisted of aggregated Pt nano-particles and were found to be strong enough for AFM imaging.