Spatial profiles of electron density, electron temperature, average ionic charge, and EUV emission of laser-produced Sn plasmas for EUV lithography
Spatial profiles of electron density, electron temperature, average ionic charge, and EUV emission of laser-produced Sn plasmas for EUV lithography
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DOI：
10.7567/jjap.56.036201
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发表时间：
2017-03-01
影响因子：
1.5
通讯作者：
Mizoguchi, Hakaru
中科院分区：
文献类型：
--
作者：
Sato, Yuta;Tomita, Kentaro;Mizoguchi, Hakaru
使用集体汤姆逊散射（TS）技术测量了用于EUV光刻的激光产生的Sn等离子体的电子密度（n（e））、电子温度（T-e）和平均离子电荷（Z）的空间分布，其转换效率（CE）对于实际应用来说足够高。对于等离子体生产，使用直径 26 μm 的 Sn 液滴作为燃料。首先，使用皮秒脉冲激光来扩展锡靶。接下来，使用二氧化碳激光器产生等离子体。通过改变皮秒和二氧化碳激光器的注入时间，产生了三种不同类型的等离子体。三种等离子体的CE不同，范围为2.8%至4.0%。对于不同的等离子体条件，n(e)、T-e 和 Z 的空间分布明显不同。然而，在所有等离子体条件下，仅在足够高的 T-e (> 25 eV) 和足够的 n(e) 范围 [10(24) -(2 x 10(25)) m(-3)] 下观察到强烈的 EUV。正如模拟预测的那样，这些等离子体参数位于高效 EUV 光源范围内。 (c) 2017 日本应用物理学会
Spatial profiles of the electron density (n(e)), electron temperature (T-e), and average ionic charge (Z) of laser-produced Sn plasmas for EUV lithography, whose conversion efficiency (CE) is sufficiently high for practical use, were measured using a collective Thomson scattering (TS) technique. For plasma production, Sn droplets of 26 mu m diameter were used as a fuel. First, a picosecond-pulsed laser was used to expand a Sn target. Next, a CO2 laser was used to generate plasmas. By changing the injection timing of the picosecond and CO2 lasers, three different types of plasmas were generated. The CEs of the three types of plasmas differed, and ranged from 2.8 to 4.0%. Regarding the different plasma conditions, the spatial profiles of n(e), T-e, and Z clearly differed. However, under all plasma conditions, intense EUV was only observed at a sufficiently high T-e (> 25 eV) and in an adequate n(e) range [10(24) -(2 x 10(25)) m(-3)]. These plasma parameters lie in the efficient-EUV light source range, as predicted by simulations. (c) 2017 The Japan Society of Applied Physics