用AFM探针诱导局域氧化工艺制备纳米样板的研究

本文介绍了纳米测量系统的组成和纳米样板的研究现状，讨论了AFM探针诱导局域氧化工艺的原理及其影响参数。用该方法进行了一维纳米结构样板的制备，并对实验结果进行了分析。     

纳米测量及纳米样板

介绍了纳米测量系统的组成以及纳米样板的研究现状．提出了两种制备纳米结构样板的方法：Si基底上的原子力显微镜(AFM)探针诱导阳极氧化工艺和Au膜上的AFM探针机械划刻工艺．最后对Si基底上制备的纳米结构样板进行了精度分析．     

基于AFM硅表面局域阳极氧化的特性研究及纳米计量标准样板的制作

基于原子力显微镜(AFM)在硅(Si)表面进行局域阳极氧化的技术,以其成本低、易加工等优势被广泛应用于各种纳米元器件的制造.本文基于AFM在Si表面进行局域阳极氧化来制作纳米计量标准样板,首先分别在接触模式和轻敲模式下进行实验,定量分析了偏置电压、移动速率和刻蚀方向等主要参数对所得纳米线尺寸的影响,从而得到标准样板制作的最佳加工参数:在探针针尖电压为-7 V、移动速率为0.3μm/s、Z Distance值为-45 nm时,可以产生稳定的标准样板结构;同时两种模式下对纳米氧化线的影响趋势相同.最后在此最佳参数下,利用AFM在Si表面进行局域阳极氧化,加工得到了一维线光栅、二维光栅和圆形光栅结构.     

典型纳米结构制备及其测量表征

针对纳米器件中的典型几何特征,制备了3种纳米结构,采用扫描电子显微镜(SEM)、原子力显微镜(AFM)等测量工具对所制备的纳米样板进行了测量、分析和表征。提出转换薄膜厚度为线宽的公称值、基于多层薄膜淀积技术制备纳米宽度结构的方法,制备出了具有名义线宽尺寸分别为20 nm、25 nm、35 nm的纳米栅线结构。用离线的图像分析算法对所制备的纳米线宽样板的线边缘粗糙度/线宽粗糙度(LER/LWR)以及栅线线宽的一致性进行了评估。实验表明所制备纳米线宽样板的栅线具有较好的一致性,LER/LWR值小,且具有垂直的侧壁。采用电子束直写技术(EBL)和感应耦合等离子体刻蚀(ICP)制备了名义高度为220 nm的硅台阶样板。实验表明刻蚀后栅线边缘LER/LWR的高频成分减少,相关长度变长,均方根偏差值(σ)增大。采用聚焦离子束(FIB)制备了纳米单台阶和多台阶结构,并对Z方向的尺度与加工能量之间的关系进行了分析。     

用SPM纳米刻蚀方法在Ti表面制备纳米结构的研究

本文用导电原子力显微镜（AFM）针尘诱导局域氧化反应的方法，在Ti膜表面制备了TiO2纳米结构。实验结果表明，Ti膜的氧化阈值为-7伏，制备的TiO2纳米线的最小线宽达到10nm，TiO2纳米线的高度和宽度随针尘偏压的增大而增大。在优化的氧化刻蚀条件下，通过控制针尘偏压和扫描方式制备出了图形化的TiO2结构，本研究表明基于导电AFM的纳米刻蚀技术将成为构筑纳米电子器件的重要工具。     

用SPM纳米刻蚀方法在Ti表面制备纳米结构的研究

本文用导电原子力显微镜 (AFM)针尖诱导局域氧化反应的方法 ,在Ti膜表面制备了TiO2 纳米结构。实验结果表明 ,Ti膜的氧化阈值为 - 7伏 ,制备的TiO2 纳米线的最小线宽达到 10nm ,TiO2 纳米线的高度和宽度随针尖偏压的增大而增大。在优化的氧化刻蚀条件下 ,通过控制针尖偏压和扫描方式制备出了图形化的TiO2 结构 ,本研究表明基于导电AFM的纳米刻蚀技术将成为构筑纳米电子器件的重要工具     

纳米尺度栅线结构的线边缘粗糙度分析和表征

为了对线边缘粗糙度(LER)和线宽粗糙度(LWR)进行分析和表征,采用电子束光刻工艺和感应耦合等离子体刻蚀工艺制备了两种纳米尺度栅线结构,用扫描电子显微镜(SEM)对所制备结构进行了检测和定性分析.基于离线SEM图像分析法提取了纳米栅线结构的线边缘轮廓.将所提取的线边缘轮廓视为随机信号,分别采用均方根偏差σ、偏斜度Sk、峭度Ku、高高相关函数和功率谱密度函数表征了LER/LWR的幅度特征、形状特征和空间特征,研究了LER/LWR各参数从光刻图形到刻蚀图形的变化,实现了LER/LWR的定量分析和表征.     

TiO2纳米管阵列的制备工艺对其光催化性能的影响

采用阳极氧化法,在醇(丙三醇、乙二醇)-水-NH4F电解液体系中制备高度有序的TiO2纳米管阵列。采用场发射扫描电子显微镜(SEM)、X射线衍射仪(XRD)对TiO2纳米管阵列的形貌和晶型结构进行表征,讨论了阳极氧化法制备工艺(阳极氧化电压、氧化时间、电解液)对TiO2纳米管的形貌、结构及其甲基橙光催化降解性能的影响;分析了退火温度对TiO2阵列的物相及其光催化性能的影响。研究结果表明,采用高电压、增加氧化时间有利于TiO2纳米管阵列光催化的提高,在其它参数相同的情况下,采用丙三醇作为电解液制备获得的TiO2纳米管阵列较乙二醇体系具有更加优异的光催化性能。     

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。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粗糙度、纳米尺寸、表面形貌观测方面的应用和存在的问题。     

纳米尺度铁电畴的扫描力显微镜成像研究进展

扫描力显微镜(SFM)作为一种新型的超分辨率近场扫描探针显微仪器正日益受到各学科领域的高度重视.在铁电材料领域,SFM是开展纳米尺度铁电畴结构成像、纳米尺度畴结构控制及纳米尺度微区的铁电性、介电性、压电性等特性研究的潜在的强有力的研究工具.本文就纳米尺度铁电畴的扫描力显微镜的成像原理的研究进展作一综述.     

Fabrication of holographic blazed grating with Fourier synthesis exposure

A simple, direct, and universal fabrication method for holographic blazed gratings is proposed and a 79 lines/mm holographic echelle grating with 4 μm depth quasi-triangular grooves experimentally demonstrated as an example of a blazed grating fabricated directly by Fourier synthesis exposure. With the method, we converted a periodic grating groove profile into the exposure energy spatial distribution on the surface of a photoresist with the response characteristics of the particular photoresist. Then the exposure energy could be decomposed into a series of sinusoidal functions using Fourier series, and realized by superposing a series of two-beam interference patterns. In contrast with mechanically ruled gratings, the fabrication process of holographic gratings is quite quick and low cost, and especially no Rowland ghosts appear in their dispersion spectrum. The reported work will offer a new approach for blazed grating fabrication with a holographic process.     

Single-shot fabrication of waveguide ternary gratings with narrow-band optical response

Single-shot fabrication of three sets of nano-scale grating structures with different periods is reported, which are constructed on a glass substrate coated with a waveguide layer made of 200-nm-thick indium tin oxide (ITO). Multiple waveguide resonance modes are observed in the visible spectral range with a bandwidth as narrow as 10 nm. Angle-resolved tuning properties of these resonance modes enable simultaneous three-color optical response of the nanodevice to cover the whole visible spectrum. This implies very simple methods for the potential design and realization of flexible optoelectronic devices.     

Interferometric characterization of phase masks

We demonstrate a novel interferometric technique for highly accurate characterization of phase masks used in optical fiber grating fabrication. The principle of the measurement scheme is based on the analysis of the interference pattern formed between the first- and zero-order beams transmitted through or reflected from the grating under test. For spatial resolution of a few millimeters, our methods allow the determination of local variations of the order of 1-microm grating period with an accuracy of a few picometers. These methods are applicable to a broad class of diffractive grating structures.     

Subwavelength triangular random gratings

A subwavelength triangular diffractive element, whose local periods are not regular as an ordinary grating but has random values within a certain range, is proposed as a substitute for a common subwavelength antireflection grating. Its diffraction properties are electromagnetically analysed by the finite-difference time-domain method. Such a random grating shows some interesting properties, including suppression of higher diffraction orders. This improves the signal-to-noise ratio of a signal wave. Also, it is found possible for a random grating to retain a diffraction effciency comparable with that of a regular grating, even when some local periods violate the subwavelength condition, provided that the random local period range is properly chosen. This is another advantage of a random grating over the regular grating in the fabrication process, because upper limitation on feature sizes is partially relieved. In addition, application to general random scattering problems is discussed.     

Theory of Electron Beam Moiré

When a specimen surface carrying a high-frequency line grating is examined under a scanning electron microscope (SEM), moiré fringes are observed at several different magnifications. The fringes are characterized by their spatial frequency, orientation, and contrast. These features of the moiré pattern depend on the spatial frequency mismatch between the specimen grating and the raster scan lines, the diameter of the electron beam, and the detailed topography of the lines on the specimen.A mathematical model of e-beam moiré is developed that expresses the spatial dependence of the SEM image brightness as a product of the local intensity of the scanning beam and the local scattering function from the specimen grating. Equations are derived that give the spatial frequency of the moiré fringes as functions of the microscope settings and the spatial frequency of the specimen grating. The model also describes the contrast of several different types of moiré fringes that are observed at different magnifications. We analyze the formation of these different fringe patterns, and divide them into different categories including natural fringes, fringes of multiplication, fringes of division, and fringes of rotation.     

Fabrication of three-dimensional polymer quadratic nonlinear grating structures by layer-by-layer direct laser writing technique

We demonstrate the fabrication of a three-dimensional (3D) polymer quadratic nonlinear (χ(2)) grating structure. By performing layer-by-layer direct laser writing (DLW) and spin-coating approaches, desired photobleached grating patterns were embedded in the guest-host dispersed-red-1/poly(methylmethacrylate) (DR1/PMMA) active layers of an active-passive alternative multilayer structure through photobleaching of DR1 molecules. Polyvinyl-alcohol and SU8 thin films were deposited between DR1/PMMA layers serving as a passive layer to separate DR1/PMMA active layers. After applying the corona electric field poling to the multilayer structure, nonbleached DR1 molecules in the active layers formed polar distribution, and a 3D χ(2) grating structure was obtained. The χ(2) grating structures at different DR1/PMMA nonlinear layers were mapped by laser scanning second harmonic (SH) microscopy, and no cross talk was observed between SH images obtained from neighboring nonlinear layers. The layer-by-layer DLW technique is favorable to fabricating hierarchical 3D polymer nonlinear structures for optoelectronic applications with flexible structural design.     

On-axis beam extinction through diffraction design and analysis

To optimize the functions of the surface-relief diffractive optical elements for optical limiters and other applications, we present a systematic design and analysis with numerical illustrations of the transmission properties of different surface-relief phase gratings and Fabry-Perot elements. The spectral response and the tolerance of fabrication errors have been included. An analysis shows that the blazed grating and the echelon grating, a multilevel element as a substitute of the blazed grating, can make the on-axis transmittance very low (less than 1% with one grating) over the broad visible band with a large tolerance of fabrication errors. The results are highly significant for the design of optical-limiting devices.     

3D印刷技术研究进展及其在防伪领域中的应用

综述了柱透镜光栅印刷技术和微透镜光栅印刷技术在国内外的研究现状及其在防伪领域中的应用,指出3D印刷技术未来的发展趋势为3D微透镜光栅动态成像技术、高线数光栅印刷技术、纸基3D直印光栅技术,这3种印刷技术均面临其发展瓶颈,如何解决其发展瓶颈将是未来研究的重点。     

Fabrication of nano-scale Cu bond pads with seal design in 3D integration applications

A method to fabricate nano-scale Cu bond pads for improving bonding quality in 3D integration applications is reported. The effect of Cu bonding quality on inter-level via structural reliability for 3D integration applications is investigated. We developed a Cu nano-scale-height bond pad structure and fabrication process for improved bonding quality by recessing oxides using a combination of SiO2 CMP process and dilute HF wet etching. In addition, in order to achieve improved wafer-level bonding, we introduced a seal design concept that prevents corrosion and provides extra mechanical support. Demonstrations of these concepts and processes provide the feasibility of reliable nano-scale 3D integration applications.