小型微纳米图形电子束曝光制作系统(英文)

为了满足科学实验过程中对制作半导体器件和微纳米结构的需要,同时避免受到昂贵的工业级电子束曝光(electron beam lithography,EBL)机的条件制约,构建了一种基于普通扫描电子显微镜(scanning electron microsco-py,SEM)的桌面级小型电子束曝光系统.建立了以浮点DSP为控制核心的高速图形发生器硬件系统.利用线性计算方法实现了电子束曝光场的增益、旋转和位移的校正算法.在本曝光系统中应用了新型压电陶瓷电机驱动的精密位移台来实现纳米级定位.利用此位移台所具有的纳米定位能力,采用标记追逐法实现了电子束曝光场尺寸和形状的校准.电子束曝光实验结果表明,场拼接及套刻精度误差小于100 nm.为了测试曝光分辨率,在PMMA抗蚀剂上完成了宽度为30 nm的密集线条曝光实验.利用此系统,在负胶SU8和双层PMMA胶表面进行了曝光实验;并通过电子束拼接和套刻工艺实现了氮化物相变存储器微电极的电子束曝光工艺.     

Fabrication and Characterization of Graphitic Carbon Nanostructures with Controllable Size,Shape, and Position

The incorporation of carbon materials in micro‐ and nanoscale devices is being widely investigated due to the promise of enhanced functionality. Challenges in the positioning and addressability of carbon nanotubes provide the motivation for the development of new processes to produce nanoscale carbon materials. Here, the fabrication of conducting, nanometer‐sized carbon structures using a combination of electron beam lithography (EBL) and carbonisation is reported. EBL is used to directly write predefined nanometer‐sized patterns in a thin layer of negative resist in controllable locations. Careful heat treatment results in carbon nanostructures with the size, shape, and location originally defined by EBL. The pyrolysis process results in significant shrinkage of the structures in the vertical direction and minimal loss in the horizontal direction. Characterization of the carbonized material indicates a structure consisting of both amorphous and graphitized carbon with low levels of oxygen. The resistivity of the material is similar to other disordered carbon materials and the resistivity is maintained from the bulk to the nanoscale. This is demonstrated by fabricating a nanoscale structure with predictable resistance. The ability to fabricate these conductive structures with known dimensions and in predefined locations can be exploited for a number of applications. Their use as nanoband electrodes is also demonstrated.     

Electrochemical characterization of parylene-embedded carbon nanotube nanoelectrode arrays

A novel parylene-embedded carbon nanotube nanoelectrode array is presented for use as an electrochemical detector working electrode material. The fabrication process is compatible with standard microfluidic and other MEMS processing without requiring chemical mechanical polishing. Electrochemical studies of the nanoelectrodes showed that they perform comparably to platinum. Electrochemical pretreatment for short periods of time was found to further improve performance as measured by cathodic and anodic peak separation of K(3)Fe(CN)(6). A lower detection limit below 0.1?μM was measured and with further fabrication improvements detection limits between 100?pM and 10?nM are possible. This makes the nanoelectrode arrays particularly suitable for trace electrochemical analysis.     

A large-area nanoscale gold hemisphere pattern as a nanoelectrode array

Two-dimensional (2D) nanostructure patterns have extensive applications in photonic devices, nanoelectronics, electrochemical devices, biosensors, catalysts and high-density magnetic recording devices. It remains a challenge to develop low-cost, high-throughput, high-resolution techniques for the fabrication of large-area (wafer-scale) 2D nanostructure array patterns with controlled feature size, shape and pitch. The present work has demonstrated a low-cost, high-throughput, high-resolution approach for the fabrication of large-area, high-quality nanostructure array patterns by nanosphere lithography combined with electroplating. The gold hemisphere array pattern obtained is capable of functioning as a nanoelectrode array (NEA) in which the gold hemispheres act as individual electrodes that are separated with an insulating polypyrrole (PPY) film. Cyclic voltammetry measurement has shown a sigmoid-shaped voltammogram, which is characteristic of electrochemical characteristics of a nanoelectrode array. NEAs are expected to find extensive applications in fundamental electrochemistry studies and electrochemical devices.     

应用于纳米制造的新型电子束抗蚀剂Calixarene的工艺研究

为了满足电子束光刻（EBL）对高分辨率、性能优秀抗蚀剂的需求,研究了将Calixarene衍生物作为电子束抗蚀剂在胶液配制、电子束曝光及显影等工艺过程中的相关技术.其中电子束曝光实验在JEOL JBX-5000LS系统上进行.实验结果表明,在入射电子能量50 keV、束流50 pA的条件下,Calixarene可以方便地形成50 nm的单线、50nm等线宽与间距的图形结构.通过与常用电子束抗蚀剂的对比,总结了Calixarene在电子束光刻性能上的优缺点,并分析了其成因.作为一种新型的高分辨率电子束光刻抗蚀剂,Calixarene有望应用在纳米结构制造、纳米尺寸器件及电路的研制等领域.     

Polycarbonate-based ordered arrays of electrochemical nanoelectrodes obtained by e-beam lithography

Ordered arrays of nanoelectrodes for electrochemical use are prepared by electron beam lithography (EBL) using polycarbonate as a novel e-beam resist. The nanoelectrodes are fabricated by patterning arrays of holes in a thin film of polycarbonate spin-coated on a gold layer on Si/Si(3)N(4) substrate. Experimental parameters for the successful use of polycarbonate as high resolution EBL resist are optimized. The holes can be filled partially or completely by electrochemical deposition of gold. This enables the preparation of arrays of nanoelectrodes with different recession degree and geometrical characteristics. The polycarbonate is kept on-site and used as the insulator that separates the nanoelectrodes. The obtained nanoelectrode arrays (NEAs) exhibit steady state current controlled by pure radial diffusion in cyclic voltammetry for scan rates up to approximately 50 mV s( - 1). Electrochemical results showed satisfactory agreement between experimental voltammograms and suitable theoretical models. Finally, the peculiarities of NEAs versus ensembles of nanoelectrodes, obtained by membrane template synthesis, are critically evaluated.     

Individual single-walled carbon nanotubes as nanoelectrodes for electrochemistry

We demonstrate the use of individual single-walled carbon nanotubes (SWNTs) as nanoelectrodes for electrochemistry. SWNTs were contacted by nanolithography, and cyclic voltammetry was performed in aqueous solutions. Interestingly, metallic and semiconducting SWNTs yielded similar steady-state voltammetric curves. We clarify this behavior through a model that considers the electronic structure of the SWNTs. Interfacial electron transfer to the SWNTs is observed to be very fast but can nonetheless be resolved due to the nanometer critical dimension of SWNTs. These studies demonstrate the potential of using a SWNT as a model carbon nanoelectrode for electrochemistry.     

Real time and in situ control of the gap size of nanoelectrodes for molecular devices

Molecular electronics is often limited by the lack of a simple method to fabricate nanoelectrodes with controlled gap size. This is partly attributed to the lack of a real time characterization in the fabrication. Here, we report a new method based on an electron induced deposition process operated in scanning electron microscopy that realizes in situ and real time characterization in the nanoelectrode fabrication; thus the gap size can be controlled easily and precisely. It is a clean and nondestructive process for carbon nanotube (CNT) electrodes. The mechanism is detailed. The nanoelectrodes have a pi-conjugated surface due to the deposition of sp(2)-rich amorphous carbon. As an application, DNA molecules are assembled between the CNT electrodes by pi-stacking interaction for current-voltage measurement. Our result provides a feasible route to prepare nanoelectrodes with controlled gap size, and it will be valuable for current efforts in molecular electronics and nanoelectronics.     

Effect of molecular adsorption on the electrical conductance of single au nanowires fabricated by electron-beam lithography and focused ion beam etching

Metal nanowires are one of the potential candidates for nanostructured sensing elements used in future portable devices for chemical detection; however, the optimal methods for fabrication have yet to be fully explored. Two routes to nanowire fabrication, electron-beam lithography (EBL) and focused ion beam (FIB) etching, are studied, and their electrical and chemical sensing properties are compared. Although nanowires fabricated by both techniques exhibit ohmic conductance, I-V characterization indicates that nanowires fabricated by FIB etching exhibit abnormally high resistivity. In addition, the resistivity of nanowires fabricated by FIB etching shows very low sensitivity toward molecular adsorption, while those fabricated by EBL exhibit sensitive resistance change upon exposure to solution-phase adsorbates. The mean grain sizes of nanowires prepared by FIB etching are much smaller than those fabricated by EBL, so their resistance is dominated by grain-boundary scattering. As a result, these nanowires are much less sensitive to molecular adsorption, which mediates nanowire conduction through surface scattering. The much reduced mean grain sizes of these nanowires correlate with Ga ion damage caused during the ion milling process. Thus, even though the nanowires prepared by FIB etching can be smaller than their EBL counterparts, their reduced sensitivity to adsorption suggests that nanowires produced by EBL are preferred for chemical and biochemical sensing applications.     

Convective Delivery of Electroactive Species to Annular Nanoband Electrodes Embedded in Nanocapillary‐Array Membranes

Significant technological drivers motivate interest in the use of reaction sites embedded within nanometer‐scale channels, and an important class of these structures is realized by an embedded annular nanoband electrode (EANE) in a cylindrical nanochannel. In this structure, the convective delivery of electroactive species to the nanoelectrode is tightly coupled to the electrochemical overpotential via electroosmotic flow. Simulation results indicate that EANE arrays significantly outperform comparable microband electrode/microchannel structures, producing higher conversion efficiencies at low Peclet number. The results of this in‐depth analysis are useful in assessing possible implementation of the EANE geometry for a wide range of electrochemical targets within microscale total analysis systems.     

Fabrication of polypyrrole-based nanoelectrode arrays by colloidal lithography

This paper describes a novel technique to produce polypyrrole-based nanoelectrodes for electrochemical detection purpose. The fabrication process relies on the creation of patterned nanotemplates i.e., nanometric gold spots surrounded by an electrically insulating material (SiO(x)). From these templates, polypyrrole nanopillars are grown by classical electrochemical methods. Atomic force microscopy demonstrates that polypyrrole grows selectively inside the gold nanotemplates. The electrochemical characterization by cyclic voltammetry showed a sigmoidal-shaped voltammogram characterizing the typical nanoelectrode array behavior.     

Nanostructuring discotic molecules on ITO support

Patterning of organic compounds on a nanometer length scale is of great interest for solar applications: defined control over the donor-acceptor interface will allow design of an optimized nano-morphology promoting exciton separation and reducing charge recombination. Herein we present an imprinting technique using anodized alumina oxide (AAO) hard templates as stamps. We show an exact pattern transfer of the AAO structures into a solution processable hexa-peri-hexabenzocoronene (HBC), a discotic small molecule with acrylate moieties which is polymerized in situ. Film fabrication is realized for a variety of nanowire dimensions on square centimeter areas. The fabrication directly on conductive glass support and control over the formation of a dense barrier layer render this approach appealing for the fabrication of fully organic nanostructured photovoltaic devices.     

Addressable nanoelectrode membrane arrays: fabrication and steady-state behavior

An addressable nanoelectrode membrane array (ANEMA) based on a Au-filled track-etched polycarbonate membrane was fabricated. The Au-filled membrane was secured to a lithographically fabricated addressable ultramicroelectrode (UME) array patterned with 25 regularly spaced (100 microm center to center spacing), 10 microm diameter recessed Pt UMEs to create 25 microregions of 10 microm diameter nanoelectrode ensembles (NEEs) on the membrane. The steady-state voltammetric behavior of 1.0 mM Ru(NH(3))(6)Cl(3) and 1.0 mM ferrocene methanol in 0.1 M KCl on each of the micro NEEs resulted in sigmoidal-shaped voltammograms which were reproducible across the ANEMA. This reproducibility of the steady-state current was attributed to the overlapping hemispherical diffusion layers at the Au-filled nanopores of each 10 microm diameter NEE of a ANEMA. The track-etched polycarbonate membranes were filled using a gold electroless deposition procedure into the 30 nm diameter pores in the membrane. Electrical connection between the Au-filled template array and the lithographic UME platform array was achieved by potentiostatic electrodeposition of Cu from an acidic copper solution into each of the 25 recessed Pt UMEs on the UME array platform. A multiplexer unit capable of addressing 64 individual micro NEEs on an ANEMA is described. ANEMAs have advantages of high reproducibility, facile fabrication, multitime reuse of lithographically fabricated UME arrays, and purely steady-state behavior.     

Ultrasensitive label-free DNA analysis using an electronic chip based on carbon nanotube nanoelectrode arrays

We report the detection of DNA PCR amplicons using an ultrasensitive label-free electronic technique based on multiwalled carbon nanotube (MWNT) nanoelectrode arrays embedded in an SiO(2) matrix. Specific PCR amplicons are reliably detected using electrochemical (EC) methods through allele-specific oligonucleotide hybridization. The inherent guanine bases in the DNA amplicon target of [Formula: see text] bases serve as signal moieties with the aid of Ru(bpy)(3)(2+) mediators, providing an amplified anodic current associated with the oxidation of guanine groups at the nanoelectrode surface. The reduced size and density of the nanoelectrode array provided by MWNTs dramatically improves the sensitivity of EC detection. In addition, the abundant guanine bases in target DNA produce a large signal. Less than [Formula: see text] target amplicons can be detected on a microspot, approaching the sensitivity limit of conventional laser-based fluorescence techniques. This method also eliminates the labelling requirement and makes the measurements much simpler. This platform can be employed for developing highly automated electronic chips with multiplex nanoelectrode arrays for quick DNA analysis.     

Reaktive Nanometer‐Multischichten als maßgeschneiderte Wärmequellen beim Fügen

Reactive nanometer multilayers as tailored heat sources for joining The use of traditional joining techniques like soldering or brazing for heat sensitive microstructures often results in damaging or stress induced deformation of the components. Therefore a technology would be desirable, where heat is produced locally and only for a short time. A very promising approach is the application of socalled reactive nanometer multilayers. Reactive nanometer multilayers consist of several hundreds or a few thousands of alternating layers wi^th thicknesses in the nanometer range that can exothermic react wi^th each other. After a local activation of the chemical reaction by an electrical spark or a laser pulse, a self‐sustaining reaction starts, which propagates parallel to the multilayer surface resulting in a stable intermetallic single layer. The peak temperature of the reaction can be above 1000 8C, but the maximum temperature is only reached for several ten milliseconds. Therefore, the heat remains localized in the vicinity of the solder layers surrounding the reactive multilayer. During the entire process the components to be joined exhibit temperatures close to room temperature. We will show new results concerning the fabrication of reactive nanometer multilayers by magnetron and ion beam sputter deposition and the fabrication of free standing nanometer multilayers.     

Nanogap Electrodes

Nanogap electrodes (namely, a pair of electrodes with a nanometer gap) are fundamental building blocks for the fabrication of nanometer‐sized devices and circuits. They are also important tools for the examination of material properties at the nanometer scale, even at the molecular scale. In this review, the techniques for the fabrication of nanogap electrodes, the preparation of assembled devices based on the nanogap electrodes, and the potential application of these nanodevices for analysis of material properties are introduced. The history, the research status, and the prospects of nanogap electrodes are also discussed.     

纳米储氢合金制备方法的研究进展

纳米储氢合金的热力学与动力学性能明显超过了相应的微米级合金 ,引起了储氢合金研究者的关注 ,而目前纳米储氢合金的制备方法仅集中于球磨法。本文总结了纳米储氢合金颗粒与复合材料的制备方法 ;并从纳米材料制备技术的角度 ,对潜在的纳米储氢合金的制备方法进行了评述     

纳米贮氢材料及其制备方法的研究进展

贮氢材料纳米化使贮氢材料的发展方向有了一个突破性的飞跃,而纳米贮氢材料的制备是贮氢材料纳米化的基础.详细介绍了纳米贮氢材料的最新研究进展,深入分析和阐述了贮氢合金纳米化提高贮氢性能的机理,综述了各种制备纳米贮氢合金的物理和化学方法,展望了今后纳米贮氢材料制备方法发展的方向和趋势.     

FIB／SEM双束系统在微纳加工与表征中的应用

简要回顾了聚焦离子束／扫描电子显微镜双束系统在国家纳米科学中心的应用。围绕透射电镜样品制备、扫描电子显微镜与扫描离子显微镜、纳米材料的二维与三维表征等材料表征,以及离子束直接刻蚀加工如光子晶体阵列器件原型加下、材料沉积加工如用于电学性能测试的四电极制作、指定点加工如原子力显微镜针尖修饰、三维加工、电子束曝光及其与聚焦离子束联合加工等纳米结构加工两方面,以一些具体实例分类进行了介绍。针对限制其应用的一些不利因素,如加工效率低、面积小、精度不足、加工损伤等问题,一些新技术如新型离子源Plasma、He^＋／Ne^＋离子等与现有Ga^＋聚焦离子束系统配合将成为未来发展方向。     

Nanowire probes for high resolution combined scanning electrochemical microscopy - atomic force microscopy

We describe a method for the production of nanoelectrodes at the apex of atomic force microscopy (AFM) probes. The nanoelectrodes are formed from single-walled carbon nanotube AFM tips which act as the template for the formation of nanowire tips through sputter coating with metal. Subsequent deposition of a conformal insulating coating, and cutting of the probe end, yields a disk-shaped nanoelectrode at the AFM tip apex whose diameter is defined by the amount of metal deposited. We demonstrate that these probes are capable of high-resolution combined electrochemical and topographical imaging. The flexibility of this approach will allow the fabrication of nanoelectrodes of controllable size and composition, enabling the study of electrochemical activity at the nanoscale.