基于LIGA技术的硬X射线纳米聚焦折射透镜的研制

X射线折射透镜是目前同步辐射纳米聚焦技术的研究前沿与热点。为实现其优异的聚焦性能，优化的理论设计是前提，而优良的制备工艺是保证和关键。本项目基于LIGA工艺，重点在于工艺的优化和结构性能的提高，以研制PMMA材质的大深度硬X射线（5~50KeV）纳米聚焦折射透镜为目的。在理论方面，使用衍射动力学及光束传播等方法对透镜性能进行模拟，设计理想面型。在器件制作方面，依托北京同步辐射装置LIGA和光刻站，采用电子束直写和同步辐射纳米光刻技术，通过制备两次掩膜版的方法来保证透镜良好的形貌，包括直角、尖角结构和侧壁粗糙度。通过改变PMMA性能获得大高宽比的高硬度PMMA结构，采用纳米阵列衬底来解决光刻胶脱胶等工艺难题，以获得拥有良好面形的硬X射线折射透镜。依据在线性能测试结果，通过优化工艺参数最终得到深度大于100微米、口径大于150微米、X射线聚焦半高全宽小于150纳米的硬X射线纳米聚焦折射透镜。

Refraction lens is presently the frontier and hot topic of research of nano-focusing technique for synchrotron radiation. For refraction lens, the optimization theoretical design is the premise, while the satisfactory fabrication process is the guarantee and key to excellent performance. This project focuses on the fabrication process optimization and plans to search for PMMA hard X-ray (5 ~ 50 KeV) refraction nano-focusing lens with great depth by LIGA technology. In theory, we use the diffraction dynamics and beam propagation method to simulate the focusing performance, and design the ideal lens surface. In fabrication, relying on Beijing Synchrotron Radiation Facility (BSRF) LIGA and lithography station, we use the electron beam of writing and the twice mask preparation to ensure the good morphology including right-angle、sharp-angle structure and the roughness of surface. Large aspect ratio and high hardness of PMMA structure are made by changing the PMMA property, the nanopillar arrays on silicon substrate are used to solve the falling-off problem of the photoresist, and then the nano-focusing refraction lens with great morphology are gotten. According to the feedback from online test results, the fabrication procedure will be optimized, the PMMA hard X-ray refraction nano-focusing lens with deeper than 100 micrometers in depth, larger than 150 micrometers in aperture diameter and less than 150 nanometers in full width at half maximum of X-ray focus will be gotten ultimately.