局域热平衡Sn等离子体极紫外辐射不透明度和发射谱的理论研究  

Theoretical investigation on extreme ultraviolet radiative opacity and emissivity of Sn plasmas at local-thermodynamic equilibrium

作　　者：高城[1] 刘彦鹏 严冠鹏 闫杰 陈小棋 侯永[1] 靳奉涛[1] 吴建华[1] 曾交龙[1,3] 袁建民 Gao Cheng;Liu Yan-Peng;Yan Guan-Peng;Yan Jie;Chen Xiao-Qi;Hou Yong;Jin Feng-Tao;Wu Jian-Hua;Zeng Jiao-Long;Yuan Jian-Min(College of Science,National University of Defense Technology,Changsha 410073,China;State Key Laboratory of Laser Interaction with Matter,Northwest Institute of Nuclear Technology,Xi’an 710000,China;College of Science,Zhejiang University of Technology,Hangzhou 310023,China;Graduate School of China Academy of Engineering Physics,Beijing 100193,China)

机构地区：[1]国防科技大学理学院,长沙410073 [2]西北核技术研究所,激光与物质相互作用国家重点实验室,西安710000 [3]浙江工业大学理学院,杭州310023 [4]中国工程物理研究院研究生院,北京100193

出　　处：《物理学报》2023年第18期94-106,共13页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12074430,11974423);激光与物质相互作用国家重点实验室开放基础研究(批准号:SKLIM2008)资助的课题。

摘　　要：锡(Sn)是13.5 nm光刻光源的材料,Sn等离子体辐射性质对光源设计意义重大.基于细致能级模型,在局域热平衡假设条件下计算得到了Sn等离子体辐射不透明度和发射谱.使用多组态Dirac-Fock方法获得了Sn^(6+)-Sn^(14+)离子的能级和辐射跃迁振子强度等基本原子参数.针对波长在13.5 nm附近的4d-4f和4p-4d跃迁系,重点考虑了4d^(m)-4f^(m)(m=1,2,3,4)和4p^(n)-4d^(n)(n=1,2,3)的电子关联效应.在大规模组态相互作用计算中,每种电荷态离子的精细能级数目约为20万.对较强的吸收谱线(振子强度大于0.01),其长度和速度表示的相对差异为20%—30%.基于精密原子参数,计算了Sn等离子体在30 eV,0.01 g/cm^(3)条件下的透射谱,与实验结果基本符合.系统计算了温度16—30 eV,密度0.0001—0.1 g/cm^(3)条件下的Sn等离子体辐射不透明度和发射光谱,分析了极紫外(extreme ultraviolet,EUV)光谱随温度和密度的变化规律.研究表明温度一定时,密度增大会使得13.5 nm附近的辐射不透明度和发射谱包络增宽.而密度一定时,随着温度的增加,辐射不透明度和发射谱在13.5 nm附近存在明显的窄化效应.本文工作有助于EUV光刻光源的设计和研究.Sn is the material for an extreme ultraviolet(EUV)light source working at 13.5 nm,therefore the radiative properties of Sn plasma are of great importance in designing light source.The radiative opacity and emissivity of Sn plasma at local thermodynamic equilibrium are investigated by using a detailed-level-accounting model.In order to obtain precise atomic data,a multi-configuration Dirac-Fock method is used to calculate energy levels and oscillator strengths of Sn^(6+)-Sn^(14+).The electronic correlation effects of 4d^(m)-4f^(m)(m=1,2,3,4)and 4p^(n)-4d^(n)(n=1,2,3)are mainly considered,which dominate the radiation near 13.5 nm.The number of fine-structure levels reaches about 200000 for each ionization stage in the present large-scale configuration interaction calculations.For the large oscillator strengths(>0.01),the length form is in accord with the velocity form and their relative difference is about 20%–30%.The calculated transmission spectra of Sn plasma at 30 eV and 0.01 g/cm^(3)are compared with the experimental result,respectively,showing that they have both good consistency.The radiative opacity and emissivity of Sn plasma at the temperature in a range of 16–30 eV and density in a scope of of 0.0001–0.1 g/cm^(3)are investigated systematically.The effects of the plasma temperature and plasma density on radiation characteristics are studied.The results show that the radiative properties near 13.5 nm are broadened with the increase of density at a specific temperature,while it is narrowed with the increase of temperature for a specific density.The present investigation should be helpful in designing and studying EUV light source in the future.

关 键 词：极紫外光源 细致能级模型 组态相互作用 

分 类 号：O539[理学—等离子体物理] TN305.7[理学—物理]