Study of the 6.x nm short wavelength radiation spectra of laser-produced erbium plasmas for BEUV lithography  

作　　者：吴涛 王倩 陈柳安 陆培祥 Tao WU;Qian WANG;Liuan CHEN;Peixiang LU(Hubei Key Laboratory of Optical Information and Pattern Recognition,School of Optical Information and Energy Engineering,Wuhan Institute of Technology,Wuhan 430205,People's Republic of China;Guangdong Intelligent Robotics Institute,Dongguan 523808,People's Republic of China)

机构地区：[1]Hubei Key Laboratory of Optical Information and Pattern Recognition,School of Optical Information and Energy Engineering,Wuhan Institute of Technology,Wuhan 430205,People's Republic of China [2]Guangdong Intelligent Robotics Institute,Dongguan 523808,People's Republic of China

出　　处：《Plasma Science and Technology》2023年第6期41-51,共11页等离子体科学和技术（英文版）

基　　金：support from Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302003)。

摘　　要：Beyond extreme ultraviolet(BEUV)radiation with a wavelength of 6.x nm for lithography is responsible for reducing the source wavelength to enable continued miniaturization of semiconductor devices.In this work,the Required BEUV light at 6.x nm wavelength was generated in dense and hot Nd:YAG laser-produced Er plasmas.The spectral contributions from the 4p–4d and 4d–4f transitions of singly,doubly and triply excited states of Er XXIV–Er XXXII in the BEUV band were calculated using Cowan and the Flexible Atomic Code.It was also found that the radiative transitions between multiply excited states dominate the narrow wavelength window around 6.x nm.Under the assumption of collisional radiative equilibrium of the laser-produced Er plasmas,the relative ion abundance in the experiment was inferred.Using the Boltzmann quantum state energy level distribution and Gram–Charlier fitting function of unresolved transition arrays(UTAs),the synthetic spectrum around 6.x nm was finally obtained and compared with the experimental spectrum.The spatio-temporal distributions of electron density and electron temperature were calculated based on radiation hydrodynamic simulation in order to identify the contributions of various ionic states to the UTAs arising from the Er plasmas near 6.x nm.

关 键 词：laser-produced plasmas unresolved transition array collisional radiative equilibrium 

分 类 号：TN24[电子电信—物理电子学] O53[理学—等离子体物理]