Max Planck Institute for Intelligent Systems , Heisenbergstrasse 3, D-70569 Stuttgart, Germany.
ACS Nano. 2013 Nov 26;7(11):9788-97. doi: 10.1021/nn403295k. Epub 2013 Nov 7.
A significant challenge to the wide utilization of X-ray microscopy lies in the difficulty in fabricating adequate high-resolution optics. To date, electron beam lithography has been the dominant technique for the fabrication of diffractive focusing optics called Fresnel zone plates (FZP), even though this preparation method is usually very complicated and is composed of many fabrication steps. In this work, we demonstrate an alternative method that allows the direct, simple, and fast fabrication of FZPs using focused Ga(+) beam lithography practically, in a single step. This method enabled us to prepare a high-resolution FZP in less than 13 min. The performance of the FZP was evaluated in a scanning transmission soft X-ray microscope where nanostructures as small as sub-29 nm in width were clearly resolved, with an ultimate cutoff resolution of 24.25 nm, demonstrating the highest first-order resolution for any FZP fabricated by the ion beam lithography technique. This rapid and simple fabrication scheme illustrates the capabilities and the potential of direct ion beam lithography (IBL) and is expected to increase the accessibility of high-resolution optics to a wider community of researchers working on soft X-ray and extreme ultraviolet microscopy using synchrotron radiation and advanced laboratory sources.
X 射线显微镜的广泛应用面临一个重大挑战，那就是难以制造出足够高分辨率的光学器件。迄今为止，电子束光刻一直是用于制造称为菲涅耳波带片（FZP）的衍射聚焦光学器件的主要技术，尽管这种制备方法通常非常复杂，由许多制备步骤组成。在这项工作中，我们展示了一种替代方法，该方法允许使用聚焦 Ga(+)束光刻术在实际上一步中直接、简单且快速地制造 FZP。这种方法使我们能够在不到 13 分钟的时间内制备出高分辨率 FZP。我们在扫描透射软 X 射线显微镜中评估了 FZP 的性能，其中可以清楚地分辨出宽度小于 29nm 的纳米结构，其截止分辨率达到 24.25nm，这证明了任何通过离子束光刻技术制造的 FZP 的最高一级分辨率。这种快速简单的制造方案说明了直接离子束光刻（IBL）的能力和潜力，并有望使更多的研究人员能够使用同步辐射和先进的实验室光源，从事软 X 射线和极紫外显微镜研究，从而获得高分辨率光学器件。
