Atomic force microscope characterization of PAH/PAZO multilayers

The buildup of a poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) layer adsorbed onto a already adsorbed layer of poly(allylamine hydrochloride) (PAH) was shown to be ruled by two processes, a nucleation process which occurs for short adsorption times and a process having longer characteristic times. During the nucleation process the adsorbed amount is seen to increase very rapidly and is dependent of PAZO concentration. The adsorbed PAZO molecules create a potential barrier that to make difficult that more molecules are adsorbed. However the presence of cations in the solution accounts for adsorption the continuation of adsorption in a second process, as they tend to be adsorbed lowering the potential barrier and allowing more PAZO molecules to be adsorbed. These processes are shown to be consistent with surface morphology evolution, it was observed an increase of roughness for short adsorption periods of time and a subsequent decrease of the surface roughness for longer adsorption times.     

基于Linux的单机全数字控制的扫描探针显微镜

扫描探针显微镜的全数字控制通常采用数字信号处理器来进行,而PC机只辅助进行数据处理和显示。本文给出一种新的全数字控制方案,即在普通PC机上使用修改了内核的Linux操作系统实现对扫描探针显微镜进行多线程、高精度的实时控制。这种方法省掉了数字信号处理器的硬件开销及其与PC机通信部分的技术投入,而充分利用PC机自身强大的运算和编程功能,实现了对扫描探针进行任意方式的操控。此方法已成功应用于一套实验室自制的超高真空扫描隧道显微镜中,得到了清洁Si(111)表面7×7重构的原子分辨像。     

一种用于光学薄膜表面无损表征的原子力显微镜

研制了一种用于大面积光学薄膜表面无损表征的新型原子力显微镜(AFM)。利用开放式样品台及探头系统可检测大尺寸、大重量的样品。样品最大尺寸可达600 mm×1000 mm。利用X、Y方向上的步进电机可实现探头在大尺寸样品表面任意位置的定位。另外还设计了优化的光点跟踪光路以实现大范围扫描成像,在扫描范围和反馈范围增大的同时,保持了较高的精度。利用步进电机和扫描器配合扫描,可得到序列图像,通过序列图像的拼接可获得更大范围的扫描图像。本文中测试了三种大面积薄膜样品,实验结果表明,单幅扫描图像最大范围达20 μm×20 μm,同时保持高的横向及纵向分辨率。     

A new bifunctional topography and current probe for scanning force microscope testing of integrated circuits

A new probe for scanning force microscope testing of ntegrated ircuits (IC) was developed enabling both investigation of topography and contactless current detection in conducting lines via evaluation of the magnetic field due to the currents by means of an anisotropic agneto- esistive (AMR) sensor. First measurements of the topography and the current detection down to 10 μA with a frequency of 1 kHz are shown on a test structure containing 15 μm and 4 μm wide conducting lines. These promising results point out an application for advanced function and failure analysis of integrated circuits in the near future.     

High-density data storage based on the atomic force microscope

The atomic force microscope (AFM), with its ability to image and modify surfaces on the nanometer scale, offers the potential for simple, compact, high-density data storage devices. At the heart of the technique is a microfabricated cantilever with a sharp tip on the end. Using modern micromachining techniques, it is possible to batch fabricate cantilevers with tips that are sharp on the scale of 100 Å. We have pursued a particular AFM storage scheme based on mechanical readback of topographic data using high-frequency piezoresistive silicon cantilevers. Areal densities of 65 Gbit/in² have been demonstrated, with readback rates greater than 10 Mbit/s. Nanoreplication techniques have been used to produce read-only disks. In addition, a write-once scheme was developed that uses integrated heating elements on the cantilevers in order to perform thermomechanical writing on a polymer substrate. Considerable progress has been made in addressing critical issues such as data rate, reliability, and practical implementation, but significant challenges still remain, both in the technology and in finding the most suitable applications     

Microwave near-field microscope based on a photonic crystal with a cavity and a controlled coupling element as a probe

It is demonstrated that a 1D photonic crystal with periodicity defects can be used as a tunable cavity that makes it possible to control resonance features in the reflection spectrum of the probe of a microwave near-field microscope based on a cylindrical cavity with a loop coupling element. The probe is sensitive to variations in the parameters of dielectric plates under study with different permittivities and thicknesses of nanometer metal layers deposited on the dielectric plates in the measurements at fixed distances from the probe tip and in contact regime.     

基于原子力显微镜的压痕模式和双模纳米力学模式在模量表征中的影响因素

原子力显微镜是表征材料微观力学性质的重要手段,本文基于原子力显微镜的压痕法和双模纳米力学法,探究薄膜/基底材料与多层二维材料杨氏模量测定过程中的影响因素,分析了基底硬度、二维材料厚度以及环境湿度对两种纳米力学表征结果的影响,为研究适用于纳米材料微观力学的测定提供参考.     

扫描探针显微镜进行细胞扫描时探针对于细胞活性的影响

扫描探针显微镜(scanning probe microsope,SPM)是近几年发展很快的一种形貌表征仪器。它的一个突出优点是,可在溶液中以很高的分辨率对细胞活体进行观察。不同于光学显微镜,SPM是利用探针和样品之间的相互作用来扫描成像,探针对细胞有力的作用。这种作用力会在扫描过程中直接影响细胞的状态。为了研究SPM成像过程中探针作用力对于细胞的影响,我们用SPM的接触模式(contact mode)和敲击模式(tapping mode)对培养液中的生物活细胞进行了较长时间的扫描观察。结果显示,尽管接触模式SPM成像清楚,但长时间的扫描会造成细胞凋零;敲击模式SPM进行长时间扫描时也会造成细胞变形,而细胞会以新的形态来适应外力的影响。     

Atomic force microscopy with carbon nanotube probe resolves the subunit organization of protein complexes

Among many scanning probe microscopies, atomic force microscopy (AFM) is a useful technique to analyse the structure of biological materials because of its applicability to non-conductors in physiological conditions with high resolution. However, the resolution has been limited to an inherent property of the technique; tip effect associated with a large radius of the scanning probe. To overcome this problem, we developed a carbon nanotube probe by attaching a carbon nanotube to a conventional scanning probe under a well-controlled process. Because of the constant and small radius of the tip (2.5-10 nm) and the high aspect ratio (1:100) of the carbon nanotube, the lateral resolution has been much improved judging from the apparent widths of DNA and nucleosomes. The carbon nanotube probes also possessed a higher durability than the conventional probes. We further evaluated the quality of carbon nanotube probes by three parameters to find out the best condition for AFM imaging: the angle to the tip axis; the length; and the tight fixation to the conventional tip. These carbon nanotube probes, with high vertical resolution, enabled us to clearly visualize the subunit organization of multi-subunit proteins and to propose structural models for proliferating cell nuclear antigen and replication factor C. This success in the application of carbon nanotube probes provides the current AFM technology with an additional power for the analyses of the detailed structure of biological materials and the relationship between the structure and function of proteins.     

The magnetic-resonance force microscope: a new tool for high-resolution, 3-D, subsurface scanned probe imaging

The magnetic-resonance force microscope (MRFM) is a novel scanned probe instrument which combines the three-dimensional (3-D) imaging capabilities of magnetic-resonance imaging with the high sensitivity and resolution of atomic-force microscopy. It will enable nondestructive, chemical-specific, high-resolution microscopic studies and imaging of subsurface properties of a broad range of materials. The MRFM has demonstrated its utility for study of microscopic ferromagnets, and it will enable microscopic understanding of the nonequilibrium spin polarization resulting from spin injection. Microscopic MRFM studies will provide unprecedented insight into the physics of magnetic and spin-based materials. We will describe the principles and the state-of-the-art in magnetic-resonance force microscopy, discuss existing cryogenic MRFM instruments incorporating high-Q, single-crystal microresonators with integral submicrometer probe magnets, and indicate future directions for enhancing MRFM instrument capabilities.     

On the reliability of scanning probe based electrostatic force measurements

The dimensions of semiconductor devices rapidly decreasing, the detection and control of spatial inhomogeneities of material properties on a sub-μm scale becomes essential.For mapping various electrical properties with nearly nm-resolution, scanning probe techniques appear to be ideally suited. However, data evaluation always involves a transfer from measured to real properties by a device depending convolution procedure.We report on our results for different modes of electrical measurements, namely scanning Kelvin probe microscopy (SKM) and scanning capacitance microscopy (SCM) on various sample systems discussing the influence of experimental parameters. In addition, results of finite element simulations on this topic are presented.It turns out that the averaging function correlating real and measured data may appear quite simple, thus making a reliable reconstruction possible. On the other hand, the existence of surface charges can drastically change the results.     

基于隧道电流检测方式的原子力显微镜纳米检测系统设计

原子力显微镜（AFM）是当前进行材料表面微观形貌观察及分析的强有力工具之一。本文主要介绍一种隧道显微镜（STM）检测方式的原子力显微镜纳米检测系统（AFM.IPC-208B）,该AFM系统设计是在STM.IPC-205B系统设计的基础上,采用隧道电流工作方式,将STM与AFM功能组合兼容。文章详细阐述了AFM.IPC-208B系统的设计原理、镜体、扫描控制以及数据采集。新设计的AFM.IPC-208B系统仍具有0.1nm的分辨率,检测范围为0～2mm×2mm,系统操作简易,工作效率高,与原STM.IPC-205B系统兼容,工作性能稳定可靠。     

低噪声原子力显微镜测量单元设计

为进一步提高大气下非接触式原子力显微镜(NC-AFM)表征样品形貌的分辨率及纵向检测灵敏度,本文提出了一种基于光偏转检测方法的新型非接触式噪声溯源抑制模型及多级隔振的机械振动噪声主动隔振装置.通过多源噪声抑制系统的设计,实现了实验环境下传递到实验装置的高低频振动由69 nm有效的衰减至0.03 nm以下.结合光偏转理论...     

Sensitivity of V-shaped atomic force microscope cantilevers based on a modified couple stress theory

A relationship based on a modified couple stress theory is developed to investigate the flexural sensitivity of a V-shaped cantilever of an atomic force microscope (AFM) taking into account the normal interaction force between the cantilever tip and the sample surface. An approximate solution to the flexural vibration problem is obtained using the Rayleigh-Ritz method. The results show that the sensitivity of the V-shaped AFM cantilever using the modified couple stress theory is smaller than that using the classical beam theory for the lower contact stiffness. However, when the contact stiffness becomes higher, the situation is reversed. Furthermore, as the ratio of cantilever thickness to internal material length scale parameter decreases, the sensitivity of the cantilever decreases.     

Voltage contrast measurements on sub-micrometer structures with an electric force microscope based test system

Electric force microscopy (EFM) testing is a promising tool for contact-less circuit internal function and failure analysis of integrated circuits (IC). Up to now several EFM-test techniques have been developed and their efficiency was mostly demonstrated on test structures with geometrical dimensions down to 1 μm not presenting the state-of-the-art. This paper presents voltage contrast measurements at sub-micrometer interconnection lines successfully demonstrating the applicability of EFM-testing in next generation ICs. For the analysis of the ability of EFM-testing regarding voltage contrast measurements at sub-micrometer structures as a first step the dependence of measurement sensitivity on the structure width and on the number of active conducting lines under the probe tip is investigated. The results will be discussed.     

基于微石英晶振的动态非接触静电力显微测量(EFM)技术

在一台基于微晶振的原子力显微镜的基础上,通过在针式传感器前端细小针尖加入可调交流偏压,获得高分辨率动态非接触静电力显微镜。此装置可以分别利用微小针尖与样品间的范德华力与附加的可调整电力信号,同时获得样品表面微观形貌特征和表面电特性,如表面电荷分布,表面电势等。     

Scanning near-field optical microscope for the characterization ofoptical integrated waveguides

A scanning near-field optical microscope for the characterization of optical integrated devices has been developed. Compatible with a normal optical characterization setup the experimental setup allows a tapered uncoated optical fiber to scan the optical device with constant height by means of a shear force control using a tuning fork, and to obtain the evanescent field emerging from it. In this way, images showing simultaneously the topography with lateral resolution better than 10 nm and vertical resolution of 1 nm, and the optical field distribution have been obtained. Images obtained over rib waveguides show the guided mode intensity distribution, allowing characterization of the propagation of the light in the device for up to 1 mm. Identification of the guided mode propagation has been achieved by comparing the images with computer simulations. Measurement of the experimental decay lengths of the evanescent field obtained by the microscope allows a determination of the effective refractive index of the structure to be made     

Atomic layer deposition for quantum dots based devices

Quantum dots (QDs) are promising candidates for the next-generation optical and electronic devices due to the out-standing photoluminance efficiency, tunable ba...     

Characterization of fritting phenomena on Al electrode for low contact force probe card

We have investigated the characteristics of fritting of thin oxide film on an aluminum electrode for application to a probe card with low contact force. The fritting is a kind of electric breakdown of oxide film on metal electrode. It can be utilized for making electric contacts between the test probe and the electrode on LSI chips without a large force. The voltage and the contact force needed to cause fritting on a sputtered Al film was measured using W, BeCu and Pd needle probes. The contact resistance was also measured. A fritting was occurred by applying a contact load of 1 mN and voltage of 5 V. The contact resistance decreases with increasing the maximum current that passes through the contact. A current of 500 mA is enough to obtain the contact resistance of 1 /spl Omega/, which is low enough in practical test of signal lines. No damages were found on the Al film by optical microscope and scanning electron microscope observation.