低温固体表面亚稳态无定形冰膜的形成与延寿机制

与传统电子束光刻技术相比，冰胶电子束光刻技术（简称冰刻）更适合在非平面衬底或易损柔性材料上构建三维微纳结构。冰刻所需的非晶态无定形冰膜具有亚稳态结构，其寿命短、极易转变成表面微观结构凹凸不平的晶态冰，难以满足大面积长时间曝光的加工要求。本项目以水蒸气在低温固体表面形成亚稳态无定形冰的过程调控为核心，围绕该过程所涉及的成冰路径、成冰形态和形态转变三个层面，结合理论分析及光学显微、拉曼光谱和电子显微的实验方法，从不同时间和空间尺度深入研究影响这三个层面的关键因素，揭示亚稳态无定形冰膜的形成及其向晶态冰转变的机制，提出水蒸气在低温固体表面形成无定形冰膜的方法以及调控其亚稳态结构寿命的策略。项目的研究成果有望为发展以冰刻为代表的低温精密制造业提供理论依据和技术支撑。

Compared with traditional electron beam lithography, ice lithography is more suitable for constructing 3D micro- and nano-structures on non-planar substrates or flexible materials. Amorphous solid water (ASW) films, which are required by ice lithography, have metastable structures, short lifetimes and are easy to transform into crystalline ice films with rough surface microstructures. Therefore, it is difficult to meet the processing requirements of large-area and long-time exposure. This project takes the process control of the formation of metastable ASW films by depositing water vapor on cryogenic surfaces as the core. The three aspects of this process including ice-formation paths, ice forms and further transformations will be investigated using combined methods of theoretical analysis and experimental investigations by using optical microscopy, Raman spectroscopy and electron microscopy. The key factors affecting these three aspects will be studied in different time and space scales to clarify the mechanism of the formation of ASW films and their transformations to crystalline ice films. The methods of forming ASW films on cryogenic surfaces and controlling their metastable structure lifetimes will be proposed. The research results of the project are expected to provide theoretical basis and technical support for the development of cryogenic precision manufacturing industry represented by ice lithography.