Sequential Stretching Lithography
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0961-O06-07
Sequential Stretching Lithography Haojing Lin1, Ocelio V Lima1, Li Tan1, Zheng Li1,2, and Jiangyu Li3 1 Department of Engineering Mechanics and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, 68588 2 Department of Mechanics and Engineering Science, Peking University, Beijing, China, People's Republic of 3 Department of Mechanical Engineering, University of Washington, Seattle, WA, 89195 ABSTRACT We developed an embossing/imprinting based nanofabrication technique, dubbed sequential stretching lithography (SSL). In this process, a master pattern is imprinted into an elastomer containing a film of uncured elastomer. The elastomer is cured and then elongated to increase feature density and reduce feature size. Replication of this substrate yields a new master that can be used in further reduction steps. One-dimensional grating features with a pitch size below 200 nm were fabricated from 750 nm-pitch grating lines. This process gives us a faithful pattern miniaturization in all aspects and, as a result, a much effective control on density and dimension regulation. INTRODUCTION Over the last years, Nanoscience and Nanotechnology has seen a significant amount of efforts aimed at producing well-defined nanostructures and they can be divided into so called ‘top-down miniaturization’ or ‘bottom-up synthesis’ approaches. Major top-down nanofabrication techniques include extreme UV photolithography (EUV), e-beam lithography (EBL), scanning probe lithography (SPL), focused ion beam lithography (FIB), embossing/imprinting lithography and among others. Extreme UV and X-rays have demonstrated the resolution down to 100 nm, however, optics capable of supporting a robust and cost-effective process still faces significant challenges [1]. Although a resolution as good as a few or tens of nanometers has been achieved in SPL, EBL and FIB respectively, it is impractical for mass production due to their serial-writing and thus, low-throughput nature [2]. On the other hand, embossing/ imprinting has been proven as a low cost, parallel processing method for direct patterning of polymers [3]. In practice, a layer of polymer thin film is cast over or displaced by a mold or stamp to produce copies of desired structural features. Feature sizes measuring 5 nanometers have been reported [4]. Further miniaturization using these methods, though, is not trivial due to the precision requirements in mold making and alignments between steps. One of the challenges, for instance, is to regulate feature density on the parent mold, thus affording tunability in structure dimension and density among copies. This acute need forms the scope of this paper, where a new nanofabrication technique that integrates feature density tunability into the easy-to-process nature of embossing/imprinting is presented. Many efforts have been invested to afford manufacture flexibility to embossing/imprinting, in which small scale structures with size or shape different from those on the master stamp were demonstrated. Pathways c
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