激光冲击辅助图形化金属亚十纳米间隙及其局部场增强特性

Increasing the resolution of patterning techniques (e.g. Moore’s law) has been one of the most challenging and also fastest advancing topics in the past decades. With the fast shrinkage of the size of the product and improvement of device performance, the corresponding fabrication method has become more and more costly and difficult. The development of manufacturing approaches with the dual capability of large-scale production and high-precision fabrication has been one of the most important research goals of laser manufacturing and related fields. With a focus on metallic materials and a base on laser shock imprinting, this proposal investigates the deformation behavior of metallic micro and nano structures under ultrahigh strain rate through experimental and numerical approaches, and also the influences of ultrafine nanogaps on the local field characteristics of volume-conserved metallic structures, in order to develop an efficient and effective patterning technique for sub-10 nm metallic nanogap fabrication. Firstly, by combining with electron beam lithography, we will investigate the deformation mechanism of metallic gaps on the order of 100 nm under laser shock. Secondly, based on the optical property characterization of the gap and numerical modeling with finite-difference time-domain method, we will study the “structure-property” relationship of this technique. Finally, we will optimize the fabrication process by using the local field enhancement factor as the objective function, and carry out a through and comprehensive investigation and analysis on the characteristics of optical fields of volume-conserved three-dimensional metallic structures fabricated from laser shock imprinting, and their relationships with the parameters in laser processing. The research in this project will provide a high-precision metallic gap patterning technique.

以“摩尔定律”为代表的图形化制造技术的精度提升是当今世界竞争最激烈、发展最迅速的课题之一。随着产品尺寸迅速缩小，性能提高的同时，制造的成本和难度显著增加。开发同时具备大规模制造和高精度制造的制造方法已成为激光先进制造及相关领域的重要研究目标之一。本项目将针对金属材料，基于激光冲击压印技术，通过实验和数值研究超高应变率作用下金属微纳结构的变形机理，结合超精细纳米间隙对恒量三维金属结构局部光强的影响特性，发展高效的亚十纳米金属间隙的快速图形化方法。首先通过结合电子束刻蚀，研究激光冲击作用下百纳米级金属间隙的变形机理；其次在此基础上研究表征间隙的光学性能，并借助于光学时域差分模拟，得到“结构-性能”的内在联系；最后以间隙局部场增强因子为目标函数进行工艺优化，对激光冲击制造的恒量三维金属结构的光学场特性与激光工艺参数的关系进行全面的探索和分析。本项目的研究能提供高精度的金属间隙图形化制备方法。

本项目完成了通过使用电子束刻蚀制备百纳米级金属结构，并进行了金属间隙的激光冲击缩距的实验探索。同时，使用分子动力学方法，对激光冲击过程中的结构响应进行模拟，结合结构的微观表征方法，实现可控制备超精细金属间隙。利用光学显微镜，对制备得到的超精细金属间隙进行局部和远场光学性能表征，并结合结构微观表征结果分析其对光学性能的影响。借助光学时域差分模拟分析了在不同波长下光与超精细金属间隙的相互作用，结合超精细金属间隙的形成特征揭示高强局部光强纳米间隙的激光冲击调控机理并进行了工艺优化。本项目的研究清晰地指出了激光冲击金属变形的机制与广泛应用价值。.总体而言，已按照设定计划较好地执行完科研任务。目前，以本项目为第一资助在领域广受认可的期刊杂志发表通讯作者文章13篇，以激光冲击金属响应为主题11篇（包括Nano Letters，International Journal of Machine Tools and Manufacture（2篇），Materials Science and Engineering: A，International Journal of Mechanical Sciences等领域内具有较好声誉的中科院一区文章9篇，多篇为唯一通讯作者论文），1篇文章获选为期刊封面（Nano Letters），此外还有多篇文章在投；以项目主持人为第一申请者获批国家发明专利15项，在审专利5项。

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