结构锡靶激光等离子体极紫外光辐射特性研究  

Characteristics of Extreme Ultraviolet Emission from Laser-Produced Plasma on Structured Sn Target

作　　者：李镇广 窦银萍[1] 谢卓[1] 王海建 宋晓伟[1] 林景全[1] Li Zhenguang;Dou Yinping;Xie Zhuo;Wang Haijian;Song Xiaowei;Lin Jingquan(School of Science,Changchun University of Science and Technology,Changchun,Jilin 130022,China)

机构地区：[1]长春理工大学理学院,吉林长春130022

出　　处：《中国激光》2021年第16期43-49,共7页Chinese Journal of Lasers

基　　金：国家自然科学基金青年科学基金(62005021);吉林省科技发展计划重点研发项目(20200401052GX)。

摘　　要：开展结构Sn靶激光等离子体极紫外光辐射特性研究,对波长为1064 nm的脉冲激光等离子体产生的极紫外光谱进行研究。实验结果表明,当激光能量为500 mJ,结构靶凹槽深度为100μm、宽度为300μm时,结构靶凹槽产生13.5 nm(2%带宽)带内光辐射积分强度的增强倍率约为平面靶的1.57倍。同时发现,凹槽对激光等离子体膨胀具有抑制作用,导致不同凹槽宽度产生最佳增强倍率所对应的激光能量不同。研究聚焦光斑尺寸对结构靶产生极紫外光辐射的影响。实验结果表明,当聚焦光斑直径与凹槽宽度接近时,凹槽的13.5 nm(2%带宽)带内光辐射积分强度的增强倍率最高。此项研究对提高极紫外光辐射强度及转换效率具有重要意义。Objective Extreme ultraviolet(EUV)radiation plays significant roles in various field applications,such as microscopy imaging,material analysis,and EUV lithography.In particular,EUV lithography is an important technology for manufacturing integrated circuits with a feature size less than 7 nm.Compared with the fuel materials of Li and Xe for EUV radiation,the tin(Sn)plasma EUV radiation has purity,broadband spectra,and high conversion efficiency at 13.5 nm.In addition,the EUV radiation with 2% bandwidth centered at 13.5 nm wavelength can be reflected by Mo and Si multilayer optical devices.The above features make the 13.5 nm EUV radiation of Sn become the source of the EUV lithography system.In practical EUV lithography applications,the Sn droplet target is selected as the source for lithography.However,the difficulties in experiment and complexity are expected when Sn droplet EUV radiation is generated.For simply studying the conversion efficiency of Sn droplet EUV radiation,we can use the metal target to replace the droplet target.In this study,we report the 13.5 nm EUV radiation from laser-produced plasma on the structured target can optimize the conversion efficiency.To the best of our knowledge,no studies have been reported on the effect of spatial constraints on EUV radiation in Sn droplet targets.This work may be helpful for further research on optimizing droplet targets to obtain higher EUV conversion efficiency.Methods The EUV spectra from plasma are created by an 800 mJ,10 ns full width at half maximum,and 1064 nm Nd∶YAG laser pulse.The groove structured Sn target is fabricated by laser ablation.The width and depth of various grooves are obtained by adjusting the ablation area and times,respectively.The target is controlled by a translating stage to ensure that each laser pulse can radiate in a fresh position.The laser is focused onto the structured target by aplano-concave lens with a focal length of 400 mm.The laser focal spot diameter is changed by moving the distance between the lens and the target

关 键 词：光谱学 极紫外辐射 激光等离子体 结构靶 光刻光源 

分 类 号：O434.13[机械工程—光学工程]