40~90 nm波段极紫外多层膜研究进展

Research developments of extreme ultra-violet multilayers for 40-90 nm

极紫外多层膜反射镜在许多科学与技术领域,如极紫外光刻、天体物理学、等离子体诊断、阿秒物理和自由电子激光等方面有重要应用。多层膜使极紫外波段反射镜在正入射条件下具有高反射率和窄带宽成为可能。多层膜反射镜是极紫外成像和光谱应用的重要器件,多层膜构成的极紫外成像系统已成功完成多个太阳单一谱线的成像观测。本文综述了40~90 nm波段最有前景的多层膜的研究进展。首先简要介绍了多层膜的基本原理,叙述了40~90 nm波段材料光学常数的测量,总结了Mg基、Sc基和镧系材料以及其他材料组成多层膜的进展,给出了目前达到的最佳反射率和带宽,阐明了多层膜的时间稳定性,从而为40~90 nm波段多层膜制备提供了技术指导。

The multilayer mirrors in the extreme ultraviolet region have significantly advanced various sci⁃entific and technological fields,including extreme ultraviolet lithography,astrophysics,plasma diagnosis,attophysics,and free electron lasers.These multilayer coatings are crucial for developing mirrors that achieve high reflectivity and narrow bandwidth at normal incidence within the extreme ultraviolet spec⁃trum.Multilayer mirrors are now key components in both imaging and spectroscopy across various applica⁃tions.Optical imaging systems equipped with multilayer mirrors have conducted numerous solar observa⁃tions in different emission lines,achieving unprecedented spatial and spectral resolutions.This paper re⁃views the progress of the most promising multilayer mirrors,covering the 40 nm to 90 nm range.Follow⁃ing a brief introduction to multilayer theory,it highlights the most promising material pairs and layer stack structures based on Mg,Sc,and lanthanides.The review emphasizes multilayer mirrors that exhibit high reflectivity within the 40 nm to 90 nm wavelength range and discusses their temporal stability.