Systematic variation of polymer jacketed fibres and the effects on tip etching dynamics

Using a chemically etched fibre probe through a plastic jacket provides a simple way to smooth a tip's surface. Convection flow in the plastic tube and lateral diffusion with fixed meniscus height has been proposed to explain such improvement. Fibres with additive thin polymer layers and bare fibres with thick untapered/tapered plastic layers have been prepared to verify the dominant mechanism. The additive layers greatly change the tip's geometry and bare‐fibres with untapered plastics cannot form tips. This confirmed that lateral diffusion dominates the etching process. Based on our investigation, we propose a new non‐meniscus end‐etching method by using tapered plastics. Unlike etching methods with meniscus, the end‐etching method can regularly form very smooth tips. It is insensitive to vibrations and temperature drifts and also suitable for most fibres.     

Fabrication of hierarchical micro/nanostructures via scanning probe lithography and wet chemical etching

In this study, we propose a simple and effective method for fabricating hierarchical silicon structures via the combination of scanning probe lithography (SPL) and wet chemical etching. Here, silicon oxide structures were protruded from a 100-oriented silicon surface, followed by the passivation of silicon nitride by AFM tip-induced local oxidation. Based on the two-dimensional (2D) silicon oxide patterns, three-dimensional (3D) microstructures with high aspect ratios were formed by wet etching with HF and KOH. A variety of combinations of SPL and the etching process allowed us to fabricate diverse silicon-based structures such as deep-etched microstructures and multi-terraced nanostructures.     

Dynamic etching method for fabricating a variety of tip shapes in the optical fibre probe of a scanning near-field optical microscope

A novel etching method for an optical fibre probe of a scanning near-field optical microscope (SNOM) was developed to fabricate a variety of tip shapes through dynamic movement during etching. By moving the fibre in two-phase fluids of HF solution and organic solvent, the taper length and angle can be varied according to the movement of the position of the meniscus on the optical fibre. This method produces both long (sharp angle) and short (wide angle) tapered tips compared to tips made with stationary etching processes. A bent-type probe for a SNOM/AFM was fabricated by applying this technique and its throughput efficiency was examined. A wide-angle probe with a 50° angle at the tip showed a throughput efficiency of 3.3 × 10⁻⁴ at a resolution of 100 nm.     

虹吸动态腐蚀大锥角光纤探针制备

基于虹吸原理和动态大锥角化学腐蚀方法进行改进融合,成功制备出理想的高光传输效率和高分辨力的光纤探针。针尖尺寸在80nm~300nm,锥角可以控制在32~°45°内。并通过SPSS(statistical product and serv ice so lutions)数据分析软件从数理统计方面客观分析了该方法与静态化学腐蚀方法的显著差异。     

Fabrication of WC micro-shaft by using electrochemical etching

Tungsten carbide (WC) micro-shaft can be used as various micro-tools for MEMS because of its high rigidity and toughness. In this study, we performed fabrication experiments of the WC micro-shaft using electrochemical etching. H₂SO₄ solution was used as the electrolyte because it can dissolve tungsten and cobalt simultaneously. Optimal electrolyte concentration and applied voltage resulting in uniform shape, good surface quality, and high material removal rate (MRR) of a workpiece were experimentally selected. A straight micro-shaft with 5 μm diameter and 3 mm length was obtained by controlling the various machining parameters. Using the fabricated micro-shafts as tools, we machined a high quality micro-hole with 8 μm diameter and a micro-groove with 9 μm width in stainless steel 304 (304 SS).     

复合湿法腐蚀工艺制备硅基三维曲面

提出了将各向异性湿法腐蚀与各向同性湿法腐蚀相结合的复合工艺,通过控制刻蚀工艺参数进行体硅加工,成功刻蚀了硅基材料三维曲面回转体结构.在各向同性腐蚀过程中,由各向异性刻蚀得到的多面体结构的表面垂直腐蚀速率与刻蚀液浓度呈指数关系,而搅拌使得多面体结构表面峰值与谷底的刻蚀液存在流速差,基于此原理可得到光滑的三维曲面.刻蚀过程中,通过各向异性湿法腐蚀控制结构深度,通过各向同性湿法腐蚀"抛光"结构曲面.最后,采用实验优化湿法腐蚀过程的工艺参数,基于直径为600～1 000 μm的圆形掩模板,在硅材料表面制备得到了高度为100～200μm的三维曲面回转结构.提出的工艺简单、有效且便于操作,有望用于制作不同曲面形状的三维硅结构及聚合物光学器件模具.     

Shape control of near-field probes using dynamic meniscus etching

Dynamic etching methods for fabricating fibre optic tips are explored and modelled. By vertically translating the fibre during etching by an HF solution under an organic protective layer, a variety of tip shapes were created. The probe taper lengths, cone angles and geometrical probe shapes were measured in order to evaluate the dynamic meniscus etching process. Fibre motion, etching rate, meniscus distortion and etching time were all found to be important variables that can be used to control the final probe shape.     

全息离子束摆动刻蚀凸面闪耀光栅制备技术

高衍射效率的凸面闪耀光栅是高光谱分辨率成像光谱仪的核心分光元件,其制作方法包括机械刻划法、电子束直写法、X射线光刻法、全息离子束刻蚀法等,其中全息离子束刻蚀法因为具备良好的各向异性,不受尺寸与曲面形状限制,杂散光低,完全没有鬼线,制造时间短等优点成为现今光栅制造领域常用方法之一.传统全息离子束刻蚀凸面光栅时基底的弯曲会...     

AFM与SNOM表征抗原抗体分子的分布与特异性作用

分析免疫系统中抗原抗体分子的分布及其特异性作用对研究生命体生理机能、疾病的诊断与治疗等方面有着重要的作用。随着免疫学研究从细胞水平向分子水平的深入,高分辨和高灵敏度仪器得到更重要和广泛地应用。简单介绍了原子力显微镜(AFM)和扫描近场光学显微镜(SNOM)的特点,对近几年AFM和SNOM原位探测细胞表面分子的研究进行了分析总结,同时着重阐述了AFM和SNOM在抗原抗体分子之间特异性作用、抗体分子结构以及细胞表面抗原抗体的分布等方面的应用。     

Mesoscopic structures and dynamics of merocyanine J-aggregate studied by time-resolved fluorescence SNOM

Time-resolved fluorescence SNOM is used to probe the mesoscopic structure and dynamics of long-chain merocyanine (C₁₈MC) J-aggregates on glass plates prepared by spin coating, casting, and casting of water-soluble polymer films. A globular structure with an average diameter of ∼ 1 µm and a height of ∼ 50 nm was attributed to the J-aggregate of C₁₈MC in the spin-coating film. In polymer films, the bandwidth of the absorption of J-aggregate is much narrower in polyvinyl alcohol (PVA, ∼ 20 nm) than that in polyvinyl sulphate (PVS, ∼ 60 nm). We have demonstrated that the large bandwidth of the spectrum is due to the inhomogeneous distribution of the J-aggregate. The fluorescence image of the J-aggregate in PVA film was rather uniform, whereas non-uniform distribution of the fluorescence was observed in PVS film. The fluorescence of C₁₈MC J-aggregate in a small domain of PVA film was a single exponential decay with a lifetime as short as 19 ps, which was shorter than that in PVS film with a two-exponential decay (average lifetime of ∼ 25 ps). The fluorescence lifetime of the J-aggregate and its single exponential behaviour are considered to be indicators of the uniform distribution of the J-aggregate. The non-uniform distribution of the J-aggregate in PVS film was interpreted in terms of electrostatic interaction between PVS and merocyanine.     

Fabrication of gold tips by chemical etching in aqua regia

We present a method to produce sharp gold tips for applications in apertureless near-field optical microscopy and spectroscopy. Thin gold wires are tapered by chemical etching in aqua regia, covered by an isooctane protective layer. Tips with apical radii of curvature of <50 nm are obtained with a 40% yield. The tip performances have been checked by shear-force imaging of amyloid fibrils samples and compared to optical fiber probes. The analysis of the tip morphology, carried out by scanning electron microscopy, shows the existence of two different etching processes occurring in bulk and at the liquid-liquid interface. A simple analytical model is presented to describe the dynamics of the tip formation at the liquid-liquid meniscus interface that fits remarkably well the experimental results in terms of tip shape and length.     

光纤激光诱导背面干法刻蚀制备二元衍射光学元件

为了降低激光直接辐照透明介电材料的表面加工粗糙度和激光能量密度刻蚀阈值,提高微光学元件的产出率,介绍了一种用固体介质作吸收层,激光直接作用在透明光学材料上进行微纳加工的激光诱导背面干法刻蚀工艺。首先,选用95氧化铝陶瓷作固体材料辅助吸收层,应用中心波长为1 064 nm的掺镱光纤激光器,在3.2 mm厚的熔融石英玻璃表面刻蚀了亚微米尺度的二维周期性光栅结构。然后,对刻蚀参数进行拟合并探讨了激光能量密度对刻蚀参数的影响。最后,观察该二元光学元件的衍射花样图形并讨论其衍射特性。实验制备了槽深为4.2 μm,槽底均方根粗糙度小于40 nm,光栅常数为25 μm的二维微透射光栅,其刻蚀阈值低于7.66 J/cm²。结果表明,应用该工艺制备二维透射光栅,降低了激光刻蚀透明材料的密度阈值及加工结构的表面粗糙度。     

Nano-patterning photosensitive polymers using local field enhancement at the end of apertureless SNOM tips

We show experimentally that local optical field enhancement can occur at the end of an apertureless SNOM tip illuminated by an external light source. Our approach consists in the use of a photosensitive polymer, placed in the tip near‐field, to record intensity distribution in the vicinity of the tip end. The excited nanometre‐size light source permits us to produce nano‐patterns on the polymer surface which are then characterized by atomic force microscopy. Experimental images show the influence, on the field enhancement, of three important experimental parameters: the polarization state of the incident light, the geometry of the external illumination and the radius of curvature of the tip apex. These results are shown to be in good agreement with two‐dimensional numerical calculations based on the finite‐difference time‐domain method. We show preliminary nanometre‐size patterns created by this nano‐source excited at a metallic tip extremity and discuss the potential of this approach for near‐field optical lithography.     

Fabrication of nanoscale step height structure using atomic layer deposition combined with wet etching

The current techniques used for the fabrication of nanosteps are normally done by layer growth and then ion beam thinning. There are also extra films grown on the step surfaces in order to reduce the roughness. So the whole process is time consuming. In this paper, a nanoscale step height structure is fabricated by atomic layer deposition(ALD) and wet etching techniques. According to the traceable of the step height value, the fabrication process is controllable. Because ALD technology can grow a variety of materials, aluminum oxide(Al_2O_3) is used to fabricate the nanostep. There are three steps of Al_2O_3 in this structure including 8 nm, 18 nm and 44 nm. The thickness of Al_2O_3 film and the height of the step are measured by anellipsometer. The experimental results show that the thickness of Al_2O_3 film is consistent with the height of the step. The height of the step is measured by AFM. The measurement results show that the height is related to the number of cycles of ALD and the wet etching time. The bottom and the sidewall surface roughness are related to the wet etching time. The step height is calibrated by Physikalisch-Technische Bundesanstalt(PTB) and the results were 7.5±1.5 nm, 15.5±2.0 nm and 41.8±2.1 nm, respectively. This research provides a method for the fabrication of step height at nanoscale and the nanostep fabricated is potential used for standard references.     

Improvement in etching efficiency of borosilicate glass by dissolving internal silver precipitates

Solid-state ion exchange with an applied voltage enables metal doping into alkali-silicate glass surfaces. The effect is especially prominent when silver is a dopant material, with additional voltage application producing silver nanowire networks in a glass substrate. We aimed to improve the wet etching efficiency of a glass substrate using internal networks as penetration paths of etchants. Silver precipitated glass when immersed in hydrofluoric acid (HF), allowing etchant infiltration via cracks around the nanowires. As a result, the silver-precipitated area was selectively dissolved, due to which blind/through-holes were formed with similar shapes. The etch rate (etched depth per unit time) of the silver-precipitated area was 1.9 μm/min, and was 3.3 times higher than that of the as-received glass (0.58 μm/min) in 20 wt% HF at 297 K.     

XPS表征Ar~+刻蚀对PET表面结构的损伤

Ar+刻蚀应用于聚合物的深度剖析中时,通常会造成聚合物表面结构的损伤,从而无法得到真实的聚合物结构信息。本实验结合X射线光电子能谱(XPS)分析测试技术,以聚对苯二甲酸乙二醇酯(PET)为对象,研究Ar+刻蚀对其表面结构的损伤,以及Ar+刻蚀参数对其损伤作用的影响。     

Improving the etching performance of high-aspect-ratio contacts by wafer temperature control: Uniform temperature design and etching rate enhancement

A novel wafer temperature control system using direct expansion cycles is developed to improve etching performance. This system enables rapid temperature control of a wafer with low power consumption. In a previous report, we confirmed that the etching rate and mask selectivity of high-aspect-ratio contact etching could be increased by around 6% and 14%, respectively, by controlling the temperature of the wafer during the etching process. In this study, an advanced wafer temperature control system that realizes not only rapid response but also uniform wafer cooling is developed, and a new etching process that controls O₂ gas flow rate as well as wafer temperature during etching is evaluated to decrease the etching rate depression of high-aspect-ratio contact etching. As a result, a rate of wafer temperature change of 1 °C/s and uniformity of ±0.7% with a coefficient of performance exceeding 3 is achieved over a wafer with a diameter of 300 mm during the etching process. Furthermore, etching rate depression in C₄F₆/Ar/O₂ plasma is decreased from 14.4% to 7.8% for a sample with a diameter of 100 nm and aspect ratio of 30.     

Localized etching of silicon in water using a catalytically active platinum-coated atomic force microscopy probe

This paper presents a novel atomic force microscopy (AFM)-based nanofabrication technique for Si in water that is based on highly localized catalytic etching with a Pt-coated AFM probe. It has been shown that nanoscale grooves can be fabricated on the Si surface at room temperature via Pt-assisted catalytic chemical etching in water without the addition of any chemicals. Furthermore, dissolved oxygen (O₂) in water has been found to be a key element for driving the chemical reaction of Si with water in the Si removal process. Experimental results have also suggested that an oscillating cantilever of the Pt-coated AFM probe for the stirring of water is essential in order to overcome the oxygen mass-transfer limitations and enhance the Si removal rate. The elementary chemical reactions taking place during the etching of Si has been estimated on the basis of electrochemical theory. It is proposed that in the first step, dissolved oxygen is reduced and forms hydroxide ions (OH⁻) with water molecules (H₂O) on the surface of the Pt-coated tip. In the second step, Si atoms are oxidized on reaction with OH⁻ ions and water soluble silicates are formed. The catalytic reaction taking place on the surface of a Pt-coated tip can be enhanced by the application of an anodic potential to an additional Pt wire electrode, resulting in a dramatic fifty-fold increase in the Si removal rate.     

Chemical etching of natural fluorapatite crystals in acid solutions studied with the scanning electron microscope

Different aspects of the chemical etching process for natural fluorapatite (FAP) crystals in pure phosphoric acid solutions and for those with additives of Ca²⁺ and H₂SO₄ have been studied by means of the scanning electron microscope. The resulting experimental data obtained in the etching process are very sensitive to dissolving conditions, type of crystal face, and the presence or absence of any epitaxial coatings on the surface of dissolving crystals. It was found that the pyramidal crystal faces of the FAP have the highest dissolution rate value and, as a result, are not etched at all. The prism and pinacoid faces usually are covered by hexagonal etch pits under the same conditions. Additives of Ca²⁺ to the phosphoric acid solution result in transition from a chemical etching to a chemical polishing process, and additives of H₂SO₄ result in epitaxial coatings of CaSO₄· xH₂O (x = 0,0.5, 2) and shapeless pits formation.     

K9玻璃亚表面损伤的分步腐蚀法测量

为了消除HF酸差动腐蚀法测试中环境因素对测试精度的影响,提出了HF酸分步腐蚀法,并引入修正系数Ki来对不同腐蚀阶段的环境变化做适当的修正以提高测量精度。采用HF酸分步腐蚀法测量了固结磨料抛光垫（FAP）研磨后K9玻璃的亚表面损伤层深度,并与HF酸差动腐蚀速率法和磁流变抛光斑点法的测量结果进行了对比研究。结果显示,用本文提出的方法测量得到的亚表面损伤层深度为3.479 μm,其他两种测量方法测得的结果分别为0.837 μm和2.82 μm。测量结果表明,分步腐蚀法的测量精度更高,其结果更加符合实际情况。另外测试中引入了实验校正系数Ki,很大程度上减少了操作环境及重复操作带来的累积误差。