紫外纳米压印技术的图形转移层工艺研究

研究了紫外纳米压印技术的图形转移层工艺,通过改变膜厚进行压印对比实验,将转速控制在3000～4000r/min,成功地得到了50nm光栅结构的高保真图形,复型精度可以达到93.75%。同时阐明,纳米压印技术由于具有超高分辨率、低成本、高产量等显著特点,将成为下一代光刻技术(NGL)的主要候选者之一。     

纳米压印用压印胶的研究进展

纳米压印需采用压印胶进行图案转移,作为压印技术的关键材料,压印胶的性能直接影响到纳米压印的质量。根据压印技术的工艺特点对压印胶进行了分类,介绍了纳米压印用热压印胶和紫外压印胶的发展研究现状和性能优缺点,分析了目前压印胶存在的主要问题,并指出压印胶的研究主要是提高压印胶的脱模性能、固化速率以及简化工艺,主要列举了含氟硅类压印胶、双表面能压印胶的性能特点,并展望了未来的发展方向。     

硅油稀释PDMS法制备紫外纳米压印软模板

软模板的制作是紫外纳米压印中关键的技术,模版的分辨率直接决定了压印图形的最小分辨率。使用具有高度均匀、100nm级孔洞阵列结构的多孔氧化铝作为母版,使用基于液态浇铸的硅油稀释聚二甲基硅氧烷(硅油和聚二甲基硅氧烷的质量比为1:2)法制备出具有规则点阵结构的软模板。通过SEM和AFM表征发现,特征图形得到了有效转移,特征尺度保持在100nm左右。相对于传统的模板制备方法,此方法成本低、流程简单、适合大规模生产,是一种非常有前途的软模板制备方法。     

气囊气缸式紫外纳米压印系统的设计

介绍了紫外纳米压印技术原理和自主研发的压印系统.设计了一种利用气囊气缸的新型找平装置,并描述了该装置的原理.研制了相应的光学系统,着重讨论了光学系统的设计和调整.最后,通过使用该系统成功制备了具有100 nm特征尺寸的纳米结构.     

基于光刻版的无留膜紫外纳米压印技术研究

针对纳米压印光刻技术中压印脱模后的留膜去除问题,提出了一种基于光刻版的无留膜紫外纳米压印技术.采用传统的光刻版作为紫外压印模版,由于模版上铬层的遮蔽作用.使得铬层下面的光刻胶不被曝光,从而可以轻易地被去除.实验结果表明,该技术综合了压印与光刻各自的优点,可以获得无留膜厚度的压印图形,省去了压印后的留膜刻蚀工艺.从而避免了由于留膜厚度不均匀所带来的过刻蚀或欠刻蚀的问题.     

紫外纳米压印OLED衬底微结构的制备技术

在有机发光二极管(OLED)器件衬底上制备可传递三维立体微结构可有效消除波导、增加出光耦合,从而增加器件出光效率。纳米压印技术是制备立体微结构的主要方法之一。采用紫外纳米压印技术在OLED衬底上制备三维立体微结构。首先采用电子束光刻(EBL)技术与干法刻蚀相结合的方法来制备高精度的紫外纳米压印模板;然后对模板进行清洗与抗粘连处理;最后采用紫外纳米压印技术在OLED衬底上成功制备了可传递三维立体微结构。制备结果表明,所形成的微结构具有均匀性好和压印精度高的特点。     

紫外固化真空负压纳米压印系统的研制

气体压力施压是实现纳米压印技术中将模板压入转移介质的重要技术路径,在克服应力不均匀、保护基片和模板等方面优势明显。报道了一种旨在提高压印压力均匀性、低压力施压的真空负压紫外固化纳米压印系统的研制。制备真空腔室,腔室顶部利用弹性橡胶环结合紫外透过性好的SiO2玻璃与腔体连接,采用抽真空的方式形成负压,腔室外大气压强通过SiO2玻璃均匀地作用到压印模板上,将其压入液态紫外敏感光刻胶中,再采用紫外光固化光刻胶,分离后实现模板图形向基板的转移。压印力大小取决于腔室内外的气体压强差,通过调节腔室内部气压大小改变施加在模板上的实际压力,内部气压大小通过连通气压表观察。图形转移实验结果表明,所研制纳米压印样机系统能够实现图形的高保真转移,在基片上形成光刻胶材质的结果图形,500nm特征线宽图形转移实验结果清晰,在较大面积基片上的压印压力均匀性良好。     

含氟紫外纳米压印光刻胶的研制

从主体树脂性质、光引发剂的选择、助剂的选择、溶剂的设计等多个方面论述了含氟纳米压印光刻胶的研制工艺。在纯有机材料为主体的光刻胶中引入了全氟丙烯酸酯助剂,解释了含氟助剂在光刻胶中的作用。使用接触角法评估了全氟丙烯酸酯对光刻胶表面性质的影响,并通过接触角数据预测了光刻胶的脱模能力。通过旋涂、压印、刻蚀等实验验证了光刻胶的性能,并通过实验数据筛选出了最佳配方。研制出的光刻胶样品图形保真度高、分辨率好,对底材有良好的黏附力,且具有良好的脱模能力。     

新型高抗粘紫外纳米压印光刻胶的工艺研究

为了减少紫外纳米压印技术脱模过程中的接触粘附力,开发了一种新型高流动、抗粘的紫外纳米压印光刻胶。光刻胶以BMA为聚合单体,添加特定配比的交联剂和光引发剂配置而成。紫外纳米压印实验在本课题组自主研发的IL-NP04型纳米压印机上完成。实验得到光刻胶掩膜膜厚为1.21μm,结构尺寸深246nm,周期937.5nm。实验结果表明,在没有对石英模板表面进行修饰的情况下,该光刻胶依然表现出高可靠性和高图形转移分辨率,有效减少了紫外纳米压印工艺中的模板抗粘修饰的工艺步骤。     

气囊气缸式真空紫外纳米压印设备研制

本文介绍了紫外纳米压印技术原理,以及工艺中模板与基片的平行度对压印质量的影响.研制了气囊气缸式真空紫外纳米压印设备,其通过气囊气缸使模板与基片平行,从而可在大面积基片上确保压力均匀.研制了相应的光学系统,着重讨论了如何实现紫外纳米压印以及光学系统的设计和调整.制备了石英玻璃模板,实现了在商用紫外固化聚合物OG154上的紫外纳米压印,转移复制了具有100nm特征的5cm×5cm面积的纳米结构图形.     

纳米压印光刻胶

光刻胶是纳米压印的关键材料,其性能将影响压印图形复制精度、图形缺陷率和图形向底材转移时刻蚀选择性。提出了成膜性能、硬度黏度、固化速度、界面性质和抗刻蚀能力等压印光刻胶的性能指标。并根据工艺特点和材料成分对光刻胶分类,介绍了热压印光刻胶、紫外压印光刻胶、步进压印式光刻胶和滚动压印式光刻胶的特点以及碳氧类纯有机材料、有机氟材料、有机硅材料做压印光刻胶的优缺点。列举了热压印、紫外压印、步进压印工艺中具有代表性的光刻胶实例,详细分析了其配方中各组分的比例和作用。介绍了可降解光刻胶的原理。展望了压印光刻胶的发展趋势。     

Nanoimprint Lithography Facilitated Plasmonic-Photonic Coupling for Enhanced Photoconductivity and Photocatalysis

Imprint lithography has emerged as a reliable, reproducible, and rapid method for patterning colloidal nanostructures. As a promising alternative to top-down lithographic approaches, the fabrication of nanodevices has thus become effective and straightforward. In this study, a fusion of interference lithography (IL) and nanosphere imprint lithography on various target substrates ranging from carbon film on transmission electron microscope grid to inorganic and dopable polymer semiconductor is reported. 1D plasmonic photonic crystals are printed with 75% yield on the centimeter scale using colloidal ink and an IL-produced polydimethylsiloxane stamp. Atomically smooth facet, single-crystalline, and monodisperse colloidal building blocks of gold (Au) nanoparticles are used to print 1D plasmonic grating on top of a titanium dioxide (TiO₂) slab waveguide, producing waveguide-plasmon polariton modes with superior 10 nm spectral line-width. Plasmon-induced hot electrons are confirmed via two-terminal current measurements with increased photoresponsivity under guiding conditions. The fabricated hybrid structure with Au/TiO₂ heterojunction enhances photocatalytic processes like degradation of methyl orange (MO) dye molecules using the generated hot electrons. This simple colloidal printing technique demonstrated on silicon, glass, Au film, and naphthalenediimide polymer thus marks an important milestone for large-scale implementation in optoelectronic devices.     

新型含硅丙烯酸酯型纳米压印胶的研究与应用

纳米压印技术因其成本低、产量高的优点广受关注,而开发可适用于纳米压印的压印胶成为该工艺的关键。合成了一种硅含量高的单体三(三甲基硅氧基)甲基丙烯酰氧丙基硅烷(TRIS),制备了一种新型紫外纳米压印用含硅丙烯酸酯型压印胶,用四点弯曲实验机和接触角测试仪表征了压印胶与模板的黏附性能,研究了配方组成对模板黏附性能的影响,优化得到了抗黏附性能优异的配方。压印实验结果表明,该压印胶与模板分离时无粘连。AFM与SEM测试结果表明,压印胶上复制得到了线宽149 nm、周期298 nm、深宽比为1的纳米光栅图形,图形结构完整。     

A Universal Scheme for Patterning of Oxides via Thermal Nanoimprint Lithography

Direct patterning of oxides using thermal nanoimprint lithography is performed using either the sol‐gel or methacrylate route. The sol‐gel method results in resists with long shelf‐life, but with high surface energy and a considerable amount of solvent that affects the quality of imprinting. The methacrylate route, which is limited to certain oxides, produces polymerizable resists, leading to low surface energy, but suffers from the shorter shelf‐life of precursors. By combining the benignant elements from both these routes, a universal method of direct thermal nanoimprinting of oxides is demonstrated using precursors produced by reacting an alkoxide with a polymerizable chelating agent such as 2‐(methacryloyloxy)ethyl acetoacetate (MAEAA). MAEAA possesses β‐ketoester, which results in the formation of environmentally stable, chelated alkoxide with long shelf‐life, and methacrylate groups, which provide a reactive monomer pendant for in situ copolymerization with a cross‐linker during imprinting. Polymerization leads to trapping of cations, lowering of surface energy, strengthening of imprints, which enables easy and clean demolding over 1 cm × 2 cm patterned area with ≈100% yield. Heat‐treatment of imprints gives amorphous/crystalline oxide patterns. This alliance between two routes enables the successful imprinting of numerous oxides including Al₂O₃, Ga₂O₃, In₂O₃, Y₂O₃, B₂O₃, TiO₂, SnO₂, ZrO₂, GeO₂, HfO₂, Nb₂O₅, Ta₂O₅, V₂O₅, and WO₃.     

纳米压印抗粘性技术研究进展

纳米压印是一种理想的光刻技术,它具有生产率和分辨率高的特点。脱模过程中,粘连限制了图形的精确转移,因此,抗粘连成为纳米压印技术需要解决的关键问题。氟化自组装单分子层是一种被广泛应用的抗粘连涂层,介绍和分析了其在耐热性和降解方面的最新研究进展。介绍了类金刚石碳膜、在光刻胶上喷涂脱模剂和含氟表面活化剂在纳米压印抗粘连研究上的进展,分析了这些方法所存在的问题及纳米压印抗粘连的发展趋势。     

基于纳米压印的超材料近红外吸收器的制备研究

超材料吸收器的高吸收率源于表面金属颗粒与介质层之间产生的局域等离激元共振以及由金属颗粒--介质层--金属反射层构成的微腔所导致的共振吸收。其吸收特性与金属颗粒的尺寸、形貌和介质层的材料和厚度密切相关。设计优化了一个在近红外波段1.2 μm处具有近完美吸收的超材料吸收器。以该设计为蓝图,利用纳米压印技术制备了一系列具有不同介质层厚度的器件,并利用红外反射谱定量研究了这些器件的吸收特性。实验结果证实,用纳米压印技术制备的超材料器件具有工艺可靠性好、加工精度高等优点。实验测得的吸收率变化趋势与理论预期相符,吸收率较高。     

Nanoimprint Lithography and the Role of Viscoelasticity in the Generation of Residual Stress in Model Polystyrene Patterns

Understanding polymer deformation during the nanoimprinting process is key to achieving robust polymer nanostructures. Information regarding this process can be extracted from monitoring the decay of the imprinted polymer patterns during thermal annealing. In the present work, the effect of both the molar mass and the imprinting temperature on the pattern decay behavior during thermal annealing is investigated. Previously, it was found that the decay rate is fastest for a highly entangled polymer due to the elastic recovery caused by the residual stress created during the imprinting process. The present paper demonstrates that this residual stress level can be modified through control of the imprinting temperature. These results are contrasted with those for an unentangled polymer over a similar range of imprinting temperatures, where it is found that the pattern decay is controlled by simple Newtonian flow. In particular, the pattern decay is well described by surface‐tension‐driven viscous flow, and no imprinting‐temperature effect is observed during thermal annealing. It is shown that the stability of the film against pattern decay can be optimized for moderately entangled polymer films. This effect is attributed to the competition between the effect of increased viscosity with increasing molar mass and increased residual stresses with entanglements. These observations provide guidance for the optimization of imprinting process in terms of selection of molar mass and processing temperatures.     

Patterned Self‐Assembled Monolayers on Silicon Oxide Prepared by Nanoimprint Lithography and Their Applications in Nanofabrication

Nanoimprint lithography (NIL) is used as a tool to pattern self‐assembled monolayers (SAMs) on silicon substrates because of its ability to pattern in the micrometer and nanometer ranges. The polymer template behaves as a physical barrier preventing the formation of a SAM in the covered areas of the substrate. After polymer removal, SAM patterns are obtained. The versatility of the method is shown in various nanofabrication schemes. Substrates are functionalized with a second type of silane adsorbate. Pattern enhancement via selective electrostatic attachment of carboxylate‐functionalized particles is achieved. Further applications of the NIL‐patterned substrates include template‐directed adsorption of particles, as well as the fabrication of electrodes on top of a SAM.     

Nanoimprint lithography fabrication of waveguide-integrated optical gratings with inexpensive stamps

We demonstrate that a replica grating can be effectively used as an inexpensive stamp for nanoimprint lithography to pattern diffractive optical couplers integrated with planar optical waveguides. Imprinted grating patterns were integrated with silicon oxynitride waveguide films to be used as an evanescent wave sensor in the input grating-coupler configuration. An anti-adhesion layer using an inexpensive, two-step chemical functionalization was developed for the stamps. The stamps were able to withstand imprint temperatures ranging from 140 to 190 °C and high fidelity imprints were obtained. The groove pattern was integrated in waveguide films by etch transfer and light-coupling properties of gratings with 1.2 μm pitch were tested using a λ = 1.55 μm laser. Compared to etched silicon masters, replica optical gratings provide uniform pattern density over their entire surface with no unstructured regions, are inexpensive, and readily available for R&D use.