Realization of various sub-micron metal patterns using room temperature nanoimprint lithography

Nanoimprint lithography (RT-NIL) process using hydrogen silsesquioxane (HSQ) provides a simple fabrication method to realize sub-micron-sized patterns because it can be applied at room temperature. When the process is performed on a HSQ-PMMA bi-layer resist, it is suitable to additional metal sputtering and lift-off process because it features negative vertical profiles. However, high viscosity of HSQ at room temperature requires a high imprint pressure, and also limits the applicable mold profile. Thus, the HSQ imprint depth dependencies on prebaking temperature and mold protrusions are investigated and results are analyzed using the equations for squeezed flow of polymers which enable us to predict typical imprint results under specific conditions. Based on these investigations, the RT-NIL process was optimized and, then, various sub-micron-sized metal patterns of line and hole array were fabricated.     

Simple and cost-effective fabrication of size-tunable zinc oxide architectures by multiple size reduction technique

Abstract

We present a simple size reduction technique for fabricating 400 nm zinc oxide (ZnO) architectures using a silicon master containing only microscale architectures. In this approach, the overall fabrication, from the master to the molds and the final ZnO architectures, features cost-effective UV photolithography, instead of electron beam lithography or deep-UV photolithography. A photosensitive Zn-containing sol–gel precursor was used to imprint architectures by direct UV-assisted nanoimprint lithography (UV-NIL). The resulting Zn-containing architectures were then converted to ZnO architectures with reduced feature sizes by thermal annealing at 400 °C for 1 h. The imprinted and annealed ZnO architectures were also used as new masters for the size reduction technique. ZnO pillars of 400 nm diameter were obtained from a silicon master with pillars of 1000 nm diameter by simply repeating the size reduction technique. The photosensitivity and contrast of the Zn-containing precursor were measured as 6.5 J cm^?2 and 16.5, respectively. Interesting complex ZnO patterns, with both microscale pillars and nanoscale holes, were demonstrated by the combination of dose-controlled UV exposure and a two-step UV-NIL.     

Effects of thermal treatment on the tribological characteristics of thermoplastic polymer film

Friction tests were carried out using a microtribometer to investigate the effect of thermal treatment on microscale friction and wear between poly(methyl methacrylate) (PMMA) film and a fused silica lens. Two films were examined: one that was baked at 413 K for 2 min and one that was baked at 433 K for 24 h. The friction forces on the PMMA films were measured under atmospheric conditions as the temperature of the films was increased from 300 K to 443 K. The contact area between the films and the lens was also examined. As the temperature increased, the friction force increased for both films. The slope of the friction force with temperature and the contact area varied, depending on the state of the film surface; glassy, rubbery, and viscous flow states. The baking conditions also affected the slope, contact area, and wear generation. For temperatures at which the samples were in a glassy state, wear particles were not generated on the sample baked for 24 h. The results demonstrate that the tribological characteristics can be altered by the thermal treatment of the PMMA film as well as the temperature. When the film contains some residual solvent, the residual solvent in the PMMA film can diffuse to the PMMA surface due to heating and thus decrease the friction force under room-temperature conditions.     

Fabrication of hydrophobic inorganic coatings on natural lotus leaves for nanoimprint stamps

Hydrophobic inorganic films were obtained by direct deposition of copper or silicon onto natural lotus leaves by ion beam sputtering deposition technique. Scanning electron microscopy observations showed a lotus-leaf-like surface structure of the deposited inorganic films. Hydrophobic nature of the inorganic films on lotus leaves had been improved compared to the inorganic films deposited on flat silicon substrates. Water contact angles measured on the lotus-leaf-like copper and silicon films were 136.3 ± 8° and 117.8 ± 4.4°, respectively. The hydrophobic lotus-leaf-like inorganic films had been repeated used as nanoimprint stamps. Negative structures of lotus-leaf-like inorganic films were obtained on the polystyrene resist layers.     

结构色颜料的加色法制备及性能研究

结构色是利用入射光与微纳米结构之间产生干涉、衍射和散射效应来实现的。物理气相沉积（Physical Vapor Deposition,PVD）工艺是制备结构色颜料的常用方法之一,通过将真空沉积的薄膜粉碎成微米尺度的薄片而获得结构色颜料。当出现新的颜色需求时,通常需要重新设计薄膜结构、优化工艺参数甚至制具等,工作量大、效率低。受到传统绘画调色的启发,解决结构色颜料上述问题的一种方法是将不同的结构色颜料进行混合,从而获得不同的颜色。与传统化学颜料或有机染料不同,结构色是以反射形式产生颜色,遵循加色法混合原则。文章研究了结构色颜料混合前后的光谱和颜色特性。混合型新颜料的光谱实测值与理论计算值一致,L*、a*、b*颜色特性值处于混合前各颜料对应的性能之间。文章提出的结构色颜料混合方法为结构色新颜色的开发提供了一种更快速且可行的方法,有利于大批量生产过程中提高良率和降低成本。     

Fabrication of polycrystalline TiO2 nanopatterns by TiO2 sol base imprint lithography

This paper reports a process for fabricating TiO₂ nano-patterns using nanoimprint lithography and a sol–gel method. An ethanol-based TiO₂ sol was prepared using tetrabutylorthotitanate as a precursor and used as an imprint resin. A replicated polydimethylsiloxane (PDMS) mold was used as an imprint stamp. During the imprinting process at 5 atm and 200 °C for 1 h, the TiO₂ sol changed to a TiO₂ gel by absorbing the solvent into the PDMS mold. After imprinting, a TiO₂ gel pattern was formed on an oxidized Si wafer. After subsequent annealing, it confirmed that patterns of the master template were transferred to TiO₂ patterns by Scanning Electron Microscopy. Furthermore, Transmission Electron Microscopy and X-Ray Diffraction showed that the TiO₂ gel patterns had been converted to an inorganic polycrystalline TiO₂ pattern.     

纳米光子结构软膜紫外光固化纳米压印

紫外光固化纳米压印是实现纳米结构批量复制的一种新技术．其特点是低成本和高分辨，而且可以达到极高的套刻精度．为了得到大面积图案的均匀复制，可用聚二甲基硅氧烷（PDMS）制备透光的压印软模板．其母版图案可由高分辨率电子柬曝光和反应离子刻蚀的方法在硅片基底上获得，然后用浇注的方法将图案转移到PDMS上．本实验特别发展了紫外光固化纳米压印适用于软膜压印的双层膜图型转移技术．该双层膜由廉价的光胶和聚甲基丙烯酸甲脂（PMMA）构成．对光胶层的压印可用普通的光学曝光仪实现．然后再将图案用反应离子刻蚀的方法转移到PMMA层中．为了证明方案的可行性，在两种不同材料的半导体基片上压印了三角晶格的光子晶体和准晶结构的图案，并用剥离的方法将它们转移到金属薄膜上，最后成功地进行了硅片刻蚀实验．相信这一纳米制做方法对大面积纳米光子结构和光学集成芯片的制造是普遍适用的．     

基于光学光刻技术的PDMS微纳敏感结构薄膜加工工艺研究

利用光学光刻技术进行多种形状规格聚二甲基硅氧烷(PDMS)微纳敏感结构的并行加工。研究了基于光学光刻技术的PDMS微纳敏感结构薄膜加工工艺,并加工出不同形状、、不同大小的PDMS微纳敏感结构。此外,对加工后的PDMS微纳敏感结构薄膜进行表征,观察了不同形状、不同大小的PDMS微纳敏感结构的形貌特征。结果表明:基于光学光刻技术的PDMS微纳敏感结构薄膜加工工艺具有加工效率高,加工过程中不需要刻蚀、激光加工等复杂工艺和昂贵设备的特点,并且实现了大批量PDMS微纳敏感结构的并行加工。同时,掩模板上的微纳图案较好地转移到PDMS薄膜上,具有较好的图案曝光成像和图形转移效果。此外,制备的PDMS微纳敏感结构形状较规则、排列整齐,并且不同形状,不同大小的PDMS微纳敏感结构都具有高度一致性较好,侧面轮廓分明,侧壁角接近90°的特征。     

下一代光刻技术展望

介绍了下一代光刻技术的技术要点,国外研究概况和进展。重点讨论了极紫外（软Ｘ射线）光刻、电子束光刻和离子束光刻技术的进展,提出了我国开展下一代光刻技术研究的技术路线。     

掩模投影成像干涉光刻研究

掩模投影成像干涉光刻技术以在很小或几乎不增加光刻系统成本的基础上来提高光刻分辨率为目的,充分利用系统的有限孔径,将掩模图形不同的空间频率分别进行传递,最终以高分辨率对掩模成像。本文阐述了IIL的基本原理,介绍了一种实验系统,并给出了部分模拟和实验结果。研究结果表明,掩模投影成像干涉光刻技术比传统投影光刻能够得到更高的光刻分辨率。     

电子束散射角限制投影光刻掩模研制

掩模制作是电子束散射角限制投影光刻(SCALPEL)的关键技术。通过优化工艺,制作出具有“纳米硅镶嵌结构”的低应力SiNx薄膜作为支撑;开发了电子束直写胶图形的加法工艺,在支撑薄膜上得到清晰的钨 / 铬散射体图形。研制出的SCALPEL掩模,其晶片尺寸为80mm,图形线宽达到0.1m,经缩小投影曝光得到78nm的图形分辨力。     

用于100nm节点ArF准分子激光光刻的相移掩模技术

用于100nm节点ArF准分子激光光刻的相移掩模(PSM)技术主要有无铬相移掩模(CPM),交替相移掩模(APSM)、衰减相移掩模(AttPSM)和混合相移掩模技术。对这些掩模的基本原理、制作方法及性能比较进行了分析研究。研究表明,无铬相位光刻(CPL)PSM和高透AttPSM 相结合构成的混合掩模最适合用于193nmArF光刻,以产生100nm节点抗蚀剂图形。     

TFT光刻平面倾斜对光刻图形的影响及改善

薄膜晶体管光刻制程中,光刻胶光刻平面位置是决定光刻图形质量的关键因素。为了在光刻机最小分辨率条件下改善光刻图形质量,本文从光刻胶内反射光线的反射特点出发,以减小光刻胶内反射光线对非光刻区域的光刻光强及增加光刻区域的光刻胶底部光刻光强为基础,推导出光刻光线倾斜入射光刻胶平面时,光刻胶光刻平面位置调整量的计算公式,并以该公式计算出的调整量对光刻胶光刻平面进行调整。结果表明：对于最小分辨率为3.0 μm的投影光刻机,进行线间距为2.2 μm的产品光刻时,以该公式计算出的调整量对光刻胶光刻平面调整后,较未调整前,光刻图形坡度角提升了13.3%,光刻胶线宽或线间距宽度(DICD)均一性改善了14.7%,光刻图形光刻胶残留得到解决。     

利用近场衍射进行接近式衍射缩小曝光的方法

通过对接近式光刻中光通过掩模版后的近场衍射特性的计算机模拟分析和曝光实验，提出了一种新型的接近式衍射小曝光方法，适用于紫外和Ｘ射线的接近曝光技术条件下，实现缩小曝光，可使实现亚半微米线宽图形的曝光和使基掩模版制作更为容易；并且具有等量缩小和焦深大的特点。