Time-resolved two-dimensional profiles of electron density and temperature of laser-produced tin plasmas for extreme-ultraviolet lithography light sources

被引:41
作者
Tomita, Kentaro [1 ]
Sato, Yuta [1 ]
Tsukiyama, Syouichi [1 ]
Eguchi, Toshiaki [1 ]
Uchino, Kiichiro [1 ]
Kouge, Kouichiro [2 ]
Tomuro, Hiroaki [2 ]
Yanagida, Tatsuya [2 ]
Wada, Yasunori [2 ]
Kunishima, Masahito [2 ]
Soumagne, Georg [2 ]
Kodama, Takeshi [2 ]
Mizoguchi, Hakaru [2 ]
Sunahara, Atsushi [3 ]
Nishihara, Katsunobu [4 ]
机构
[1] Kyushu Univ, Interdisciplinary Grad Sch Engn Sci, 6-1 Kasugakoen, Kasuga, Fukuoka 8168580, Japan
[2] Gigaphoton Inc, 400 Yokokurashinden, Oyama, Tochigi 3238558, Japan
[3] Purdue Univ, Ctr Mat Extreme Environm CMUXE, Sch Nucl Engn, 500 Cent Dr, W Lafayette, IN 47907 USA
[4] Osaka Univ, Inst Laser Engn, 2-6 Yamadaoka, Suita, Osaka 5650871, Japan
关键词
SCATTERING;
D O I
10.1038/s41598-017-11685-0
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Time-resolved two-dimensional (2D) profiles of electron density (n(e)) and electron temperature (T-e) of extreme ultraviolet (EUV) lithography light source plasmas were obtained from the ion components of collective Thomson scattering (CTS) spectra. The highest EUV conversion efficiency (CE) of 4% from double pulse lasers irradiating a Sn droplet was obtained by changing their delay time. The 2D-CTS results clarified that for the highest CE condition, a hollow-like density profile was formed, i.e., the high density region existed not on the central axis but in a part with a certain radius. The 2D profile of the in-band EUV emissivity (eta(EUV)) was theoretically calculated using the CTS results and atomic model (Hullac code), which reproduced a directly measured EUV image reasonably well. The CTS results strongly indicated the necessity of optimizing 2D plasma profiles to improve the CE in the future.
引用
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页数:7
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