压印光刻工艺中光刻胶填充流变模拟与试验研究

压印光刻工艺中,为了实现高质量的压印复型,必须能够理解和预测压印载荷作用下光刻胶的流变填充行为。根据实际采用的光刻胶的特性,建立了基于粘性流体的光刻胶流变填充有限元模型,采用体积率法对光刻胶流场的运动边界进行追踪,研究模板特征几何尺寸、胶层厚度及及尺度效应对压印填充过程的影响及其作用机理。结果表明,光刻胶流变填充以单峰或双峰两种模式进行,模式的转变点可由特征凹槽宽度和初始胶厚度的比值来预测,并受表界面效应的影响;最有利于填充的特征深宽比约为0.8;最佳初始胶层厚度约为特征深度的2倍。进行了相应的压印试验,试验结果与模拟计算的结论吻合,说明仿真结果可信,可以作为压印光刻工艺中模板图形几何特征、胶厚以及模板表面处理的工艺设计依据。     

我国机电产品出口跃居世界第三紫外纳米压印模板表面修饰工艺研究

研究紫外纳米压印技术的模板表面修饰工艺,对经过表面修饰的模板与未经修饰的模板得到的不同压印结果,通过大量实验进行对比分析,验证模板表面修饰工艺是有效控制压印结果,确保压印复型精度的关键.     

冷压印光刻工艺精密定位工作台的研制

冷压印光刻工艺是一种将模板图形翻制到硅片上的技术。为了获得高分辨率压印图形，为压印光刻机设计了一个精密定位工作台。精密定位工作台是压印光刻机的关键部件，它既能够保证模板-抗蚀剂-硅片结构间的接触均匀一致，并实现模板与承片台间的三个运动自由度，即沿z轴的直线运动和绕x、y轴的旋转运动(α和β)，又可以实现步进对准所需要的沿x、y轴的直线运动和绕z轴的旋转运动(θ)。设计中采用了柔性机械结构，消除了使用铰链连接所引起的间隙与摩擦等问题。压印实验结果显示定位系统在200mm的行程中，精密定位工作台定位精度达到8nm以内。实现了压印光刻工艺在集成电路制造中的高精度定位要求。     

下一代光刻技术——压印光刻

通过分析集成电路制造工艺中的核心环节--光刻技术,采用机械微复形原理的压印光刻技术可避免传统光学光刻的光学衍射限制,能够对最小到6 nm特征尺寸的图形进行复制.通过研究压印光刻原理,详细分析对比热压印及常温压印的工艺特点、复形面积、模具结构和阻蚀胶固化过程等,揭示出常温压印更适用于多层套刻的图形制作.针对基于紫外光固化的常温压印光刻工艺在压印过程中的关键技术:阻蚀胶成膜控制、对准、套刻、精确加载、留膜厚度控制、阻蚀胶固化控制等进行深入研究,提出释放保形软压印工艺,能够实现基于常温软模具压印的大面积亚100 nm级特征尺寸图形的复制.最后,以SIL-Ⅰ型分步式常温紫外光固化压印光刻机的研究为例,对其结构特性做出深入分析,估算出系统的精度等级;通过试验,对系统的压印复形精度做出评估.     

基于柔性纳米压印工艺制备中红外双层金属纳米光栅

用纳米压印工艺制备红外金属光栅时,硬模板压印极易造成光栅结构缺陷致使光栅性能下降。本文采用柔性纳米压印工艺作为替代方法制备了适合在3-5μm波段工作,高度为100nm,上下金属层厚为40nm的双层金属纳米光栅,其光栅结构参数为:周期200nm,线宽100nm,深宽比1∶1。该方法采用热纳米压印工艺将母模板光栅结构复制到IPS(Intermediate Ploymer Sheet)材料上,制作出压印所需软模板;随后通过紫外纳米压印工艺将IPS软模板压印到STU-7压印胶,得到结构完整均匀的介质光栅;最后在介质光栅上垂直热蒸镀金属铝,完成中红外双层金属纳米光栅的制备。对所制备光栅进行了测试,结果表明,所制备光栅在2.5~5μm波段的TM偏振透射率超过70%,在2.7~5μm波段的消光比超过30dB,在2.72~3.93μm波段的消光比超过35dB,显示了优异的消光比特性和偏振特性。该研究结果在红外偏振探测、红外偏振传感等方面具有潜在应用。     

一种微区微纳米压印技术及设备

本文介绍了一种新型的分布微区微纳米压印技术。相比于传统的微纳米压印技术,本文所提出的压印主要技术特征在于,通过对尺寸在几十微米至数毫米范围的微小区域单元的压印组合,实现大幅面微纳米结构的制作。这种压印方式还具有的优点是,在计算机控制下压印模仁可在工作平面内旋转,各微区压印单元有不同的压印取向,压印力大小均可由程序设定,因而可以实现每个单元压印深度的控制。本文给出了微区微纳米压印技术的设计思想、实现方法以及实验结果。该技术和装备,特别适合大幅面光学衍射图像、平板显示器件的微结构制作。     

基于聚合物模板的变种压印工艺研究

纳米尺度的结构成形是纳米技术和纳米制造中的核心工艺之一。纳米压印技术以高分辨率、高效率、低成本的独特优势已经成为具有广泛应用前景的纳米成形工艺方法。压印模板是压印技术的核心要素,压印模板的特性也决定了压印工艺的技术路线和特点。因此,研究和开发新型的压印模板及其相应的新压印工艺是压印技术研究方向的主要课题。     

一种提高压印光刻软模复制精度的方法

由于传统的光刻生产工艺有透镜光学极限性 ,压印光刻为集成电路的生产提供了一种新思路。在压印光刻中 ,模具的制造是重点。为了获得高精度的压印模具 ,在实验中着重从模具材料的选择、固化剂的添加量、真空压力大小、固化温度、固化时间等方面进行分析和研究。采用正交实验方式和数理方差分析 ,通过检测压印模具的平整度、一致性、特征尺寸及模具表面的固化收缩率等参数的变化 ,特别是模具的特征尺寸变化 ,得到了压印模具制作的最佳工艺组合     

基于ABAQUS的微结构滚压印仿真

借助有限元软件ABAQUS,对滚动热压印成型过程进行二维仿真。聚合物材料采用PM-MA的理想弹塑性模型,以图形面积的复制率、图形的最大宽度和最大深度为评定判据,详细分析了滚子与聚合物表面距离、图案大小、图案占空比、滚子的滚动速度、聚合物弹性模量对压印图形质量及压印力的影响。仿真计算结果表明,滚子与聚合物的距离、图案占空比、聚合物的弹性模量对压印图形的质量影响较大,而滚子滚动速度以及图案大小对压印图形的质量影响较小;同时,滚子与聚合物距离、聚合物弹性模量、图案大小对压印力的影响较大,反之,其他的情况基本可以忽略。     

光刻热熔微透镜阵列的电铸成形复制技术研究

我们运用光刻胶热熔成形的方法,制作了２０×２０ｍｍ的光刻胶折射型微透镜阵列,单元微透镜相对口径为Ｆ／２,单元透镜直径９０μｍ,中心间隔１００μｍ。在此基础上,采用微电铸镍的方法进行成形复制技术的研究,获得了表面图形转移质量和基底性能均良好的镍模板。本文详细讨论了电铸成形技术的工艺参数控制,以及所得的电铸镍板图形质量分析。     

Molecular dynamics study of pattern transfer in nanoimprint lithography

A molecular dynamics simulations model of nanoimprint lithography (NIL) is proposed in order to study the pattern transfer and its related phenomena. The proposed model is similar to a real NIL process imprinting an α-quartz stamp with a rectangular line pattern into an amorphous poly-(methylmethacrylate) (PMMA) film. The polymer deformation behavior and the adhesion and friction effects between the stamp and the polymer film are investigated and their dependency on the pattern aspect ratio is discussed. Force fields including bond, angle, torsion, van der Waals, and electrostatic potentials are used to describe intermolecular and intramolecular interacting forces. Nosé-Hoover thermostat is used to control the temperature of the polymer film and cell multipole method is adopted to treat long range interactions. The deformation of the polymer film is observed for two stamps having different aspect ratio patterns. The distributions of density and stress in the polymer film are calculated for the detail analysis of deformation behavior. For a high aspect ratio pattern (aspect ratio = 2.5, imprint depth = 8.0 nm), large amount of springback of the residual polymer film is observed, which is mainly due to the residual compressive stress left in the polymer film. However, for a low aspect ratio pattern (aspect ratio = 1.0, imprint depth = 3.0 nm), the springback is not observed. In addition, adhesion and friction forces are obtained by dividing the polymer film into subregions and calculating the interacting force between each subregion and the stamp. While the adhesion force is nearly constant regardless of the pattern aspect ratio, the friction force increases as the pattern aspect ratio grows, so the friction force becomes larger than the adhesion force when the pattern aspect ratio increases.     

An ice lithography instrument

We describe the design of an instrument that can fully implement a new nanopatterning method called ice lithography, where ice is used as the resist. Water vapor is introduced into a scanning electron microscope (SEM) vacuum chamber above a sample cooled down to 110 K. The vapor condenses, covering the sample with an amorphous layer of ice. To form a lift-off mask, ice is removed by the SEM electron beam (e-beam) guided by an e-beam lithography system. Without breaking vacuum, the sample with the ice mask is then transferred into a metal deposition chamber where metals are deposited by sputtering. The cold sample is then unloaded from the vacuum system and immersed in isopropanol at room temperature. As the ice melts, metal deposited on the ice disperses while the metals deposited on the sample where the ice had been removed by the e-beam remains. The instrument combines a high beam-current thermal field emission SEM fitted with an e-beam lithography system, cryogenic systems, and a high vacuum metal deposition system in a design that optimizes ice lithography for high throughput nanodevice fabrication. The nanoscale capability of the instrument is demonstrated with the fabrication of nanoscale metal lines.     

大面积软X射线自支撑金透射光栅的研制

针对等离子体诊断及空间环境探测等领域对软X射线透射光栅的需要,采用全息光刻和微电镀技术制作了自支撑软X射线金透射光栅.在基底与光刻胶之间增加减反膜层以降低高反射基底引起的驻波效应对掩模槽形的影响,使用全息光刻技术获得了侧壁陡直的光栅掩模.然后,在掩模顶部镀保护层并使用反应离子刻蚀获得电镀掩模,通过改变保护层厚度来调节电...     

Contact mechanics of a flexible imprinter for photocured nanoimprint lithography

A flexible imprinter can be used to accommodate substrate or template roughness in nanoimprint lithography. The contact mechanics of a multi-layer imprinter incorporating bending and local deformation is described. With the right combination of dimensions, moduli, and viscosity, the imprinter can transfer a pattern evenly to a non-flat substrate. These concepts have been used to pattern magnetic media for high density information storage.     

NANOIMPRINT LITHOGRAPHY TECHNOLOGY WITH AUTOMATIC ALIGNMENT

Nanoimprint lithography (NIL) is recognized as one of the most promising candidates for the next generation lithography (NGL) to obtain sub-100 nm patterns because of its simplicity, high-throughput and low-cost. While substantial effort has been expending on NIL for producing smaller and smaller feature sizes, considerably less effort has been devoted to the equally important issue—alignment between template and substrate. A homemade prototype nanoimprint lithography tool with a high precision automatic alignment system based on Moiré signals is presented. Coarse and fine pitch gratings are adopted to produce Moiré signals to control macro and micro actuators and enable the substrate to move towards the desired position automatically. Linear motors with 300 mm travel range and 1 μm step resolution are used as macro actuators, and piezoelectric translators with 50 μm travel range and 1 nm step resolution are used as micro actuators. In addition, the prototype provides one translation (z displacement) and two tilting motion(α and β ) to automatically bring uniform intact contact between the template and substrate surfaces by using a flexure stage. As a result, 10 μm coarse alignment accuracy and 20 nm fine alignment accuracy can be achieved. Finally, some results of nanostructures and micro devices such as nanoscale trenches and holes, gratings and microlens array fabricated using the prototype tool are presented, and hot embossing lithography, one typical NIL technology, are depicted by taking nanoscale gratings fabrication as an example.     

Digital in-line holography on amplitude and phase objects prepared with electron beam lithography

We report on the fabrication and characterization of amplitude and phase samples consisting of well defined Au or Al features formed on ultrathin silicon nitride membranes. The samples were manufactured using electron beam lithography, metallization and a lift-off technique, which allow precise lateral control and thickness of the metal features. The fabricated specimens were evaluated by conventional microscopy, atomic force microscopy and with the digital in-line holography set-up at the Lund Laser Centre. The latter uses high-order harmonic generation as a light source, and is capable of recovering both the shape and phase shifting properties of the samples. We report on the details of the sample production and on the imaging tests with the holography set-up.     

用于1 m Seya-Namioka单色仪的 1 200 lp/mm Laminar光栅

针对国家同步辐射实验室燃烧与火焰实验站中1 m Seya-Namioka 单色仪对光栅的需求,采用全息离子束刻蚀工艺制作了1 200 lp/mm Laminar光栅。首先,通过光刻胶灰化技术调节光刻胶光栅掩模占空比,在理论设计的误差允许范围内,对此光栅掩模进行扫描离子束刻蚀;然后,将光栅图形转移到光栅基底中去除残余光刻胶;最后,采用离子束溅射法镀制厚约40 nm的金反射膜,采用热蒸发法镀制厚约60 nm的铝反射膜。用原子力显微镜分析光栅微结构,结果显示光栅槽深为40 nm,占空比为0.45。同步辐射在线波长扫描测试结果表明,镀铝光栅效率明显高于镀金光栅,获得的实验结果与理论计算结果基本符合。镀金光栅已替代进口光栅在线使用3 年,其寿命大大超过复制光栅,基本满足了燃烧实验站的实验研究需求。     

Fidelity of soft nano-imprint lithographic replication of polymer masters fabricated by two-photon polymerization

Using modern laser fabrication techniques such as two-photon polymerisation (2PP), complex 3D and planar structures with the resolutions down to 100?nm can be achieved. Advantages of 2PP can be exploited by combining it with the nano-imprint lithography (NIL). We report on the fabrication of masters by 2PP and its replicas by the soft NIL technique using poly(dimethylsiloxane) (PDMS). With PDMS stamps, very reproducible replicas of the master can be created. The stamp surface quality can be better than that of the master due to hydrostatic pressure during the stamp fabrication. Putting the stamp under stress allows the fabrication of structures with controllable reduction of the structural dimensions in one direction compared to the original master. Experimental investigations of the shape transfer fidelity and surface roughness of the replicas are presented.     

多方向金属光栅偏振器及在偏振导航中的应用

在同一聚碳酸酯基底上制作了6个不同方向的双层金属光栅偏振器,用于消除分立器件带来的安装误差。将该偏振器应用于偏振导航传感器上并进行了测角精度测试,基于神经网络法研究了角度测量的误差补偿方法。首先,基于严格耦合波理论设计了一种亚波长双层金属光栅偏振器,分析了它的周期和金属厚度对偏振器性能的影响,其在510nm波长入射时TM偏振光透射率高于71%,消光比大于2 100。应用纳米压印技术在聚碳酸酯基底上加工制作了设计的偏振器,其基底上设有6块结构参数相同但朝向不同的双层金属光栅结构。将此偏振器安装在偏振导航传感器上并在测试平台上测试了测角精度,测试的原始误差在±1°以内;经BP神经网络法误差补偿后,测角误差在±0.2°以内。得到的结果可较好地满足偏振导航的要求。