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

被引：38

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

来源：

SCIENTIFIC REPORTS | 2017年 / 7卷

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

页数：7