Mitigation of energetic ion debris from Gd plasma using dual laser pulses and the combined effect with ambient gas  

作　　者：窦银萍 孙长凯 刘超智 高健 郝作强 林景全 

机构地区：[1]School of Science,Changchun University of Science and Technology

出　　处：《Chinese Physics B》2014年第7期505-509,共5页中国物理B（英文版）

基　　金：supported by the National Basic Research Program of China (Grant No. 2013CB922404);the National Natural Science Foundation of China (Grant Nos. 11074027,61178022,11274053,and 11211120156);the Science & Technology Department of Jilin Province,China (Grant No. 20111812);the Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20122216120009,20122216110007,and 20112216120006);the Young Scientists Fund of Changchun University of Science and Technology,China (Grant No. 000520).

摘　　要：For the next-generation beyond extreme ultraviolet lithography （EUVL） sources, gadolinium （Gd） plasma with emis- sion wavelength at 6.7 nm seems to be the leading candidate. Similar to the Sn target 13.5 nm light source, ion debris mitigation is one of the most important tasks in the laser-produced Gd plasma EUV source development. In this paper, a dual-laser-pulse scheme, which uses a low energy pulse to produce a pre-plasma and a main pulse after a time delay to shoot the pre-plasma, is employed to mitigate the energetic ion generation from the source. Optimal conditions （such as pre-pulse energy and wavelength, and the time delay between the pre-pulse and the main pulse for mitigating the ion energy） are experimentally obtained, and with the optimal conditions, the peak of the ion energy is found to be reduced to 1/18 of that of a single laser pulse case. Moreover, the combined effect by applying ambient gas to the dual-pulse scheme for ion debris mitigation is demonstrated, and the result shows that the yield of Gd ions is further reduced to around 1/9 of the value for the case with dual laser pulses.For the next-generation beyond extreme ultraviolet lithography （EUVL） sources, gadolinium （Gd） plasma with emis- sion wavelength at 6.7 nm seems to be the leading candidate. Similar to the Sn target 13.5 nm light source, ion debris mitigation is one of the most important tasks in the laser-produced Gd plasma EUV source development. In this paper, a dual-laser-pulse scheme, which uses a low energy pulse to produce a pre-plasma and a main pulse after a time delay to shoot the pre-plasma, is employed to mitigate the energetic ion generation from the source. Optimal conditions （such as pre-pulse energy and wavelength, and the time delay between the pre-pulse and the main pulse for mitigating the ion energy） are experimentally obtained, and with the optimal conditions, the peak of the ion energy is found to be reduced to 1/18 of that of a single laser pulse case. Moreover, the combined effect by applying ambient gas to the dual-pulse scheme for ion debris mitigation is demonstrated, and the result shows that the yield of Gd ions is further reduced to around 1/9 of the value for the case with dual laser pulses.

关 键 词：extreme ultraviolet source laser-induced plasma Gd plasma ion debris 

分 类 号：O53[理学—等离子体物理]