邓巍巍, 翟天琪, 高立豪, 许晟昊, 赵新彦, 刘艳初. 面向EUV光源的实验流体力学研究进展. 力学进展, 2024, 54(1): 138-172 doi: 10.6052/1000-0992-23-044 引用本文: 邓巍巍, 翟天琪, 高立豪, 许晟昊, 赵新彦, 刘艳初. 面向EUV光源的实验流体力学研究进展. 力学进展, 2024, 54(1): 138-172 doi: 10.6052/1000-0992-23-044 Deng W W, Zhai T Q, Gao L H, Xu C H, Zhao X Y, Liu Y C. Recent progress of experimental fluid mechanics for EUV sources. Advances in Mechanics, 2024, 54(1): 138-172 doi: 10.6052/1000-0992-23-044 Citation: Deng W W, Zhai T Q, Gao L H, Xu C H, Zhao X Y, Liu Y C. Recent progress of experimental fluid mechanics for EUV sources. Advances in Mechanics , 2024, 54(1): 138-172 doi: 10.6052/1000-0992-23-044 邓巍巍, 翟天琪, 高立豪, 许晟昊, 赵新彦, 刘艳初. 面向EUV光源的实验流体力学研究进展. 力学进展, 2024, 54(1): 138-172 doi: 10.6052/1000-0992-23-044 引用本文: 邓巍巍, 翟天琪, 高立豪, 许晟昊, 赵新彦, 刘艳初. 面向EUV光源的实验流体力学研究进展. 力学进展, 2024, 54(1): 138-172 doi: 10.6052/1000-0992-23-044 Deng W W, Zhai T Q, Gao L H, Xu C H, Zhao X Y, Liu Y C. Recent progress of experimental fluid mechanics for EUV sources. Advances in Mechanics, 2024, 54(1): 138-172 doi: 10.6052/1000-0992-23-044 Citation: Deng W W, Zhai T Q, Gao L H, Xu C H, Zhao X Y, Liu Y C. Recent progress of experimental fluid mechanics for EUV sources. Advances in Mechanics , 2024, 54(1): 138-172 doi: 10.6052/1000-0992-23-044 作者简介:

邓巍巍, 南方科技大学教授, 长江学者特岗教授. 曾任美国弗吉尼亚理工大学长聘副教授, 获得美国NSF CAREER Award. 研究领域微尺度实验流体力学. 主持国家自然科学基金重点项目和专项项目, 发表SCI论文70余篇

刘艳初, 南方科技大学研究助理教授. 2011—2019在华南理工大学分别获得学士和博士学位, 2019—2021年在南方科技大学博士后流动站工作. 研究方向是激光与流体靶的相互作用和流体靶的产生与调控. 主持省部级基金和博士后基金各一项. 研究成果发表在《Journal of Fluid Mechanics》和《Physical Review Fluids》等期刊上

通讯作者: liuyc@sustech.edu.cn

中图分类号: O35

EUV (极紫外)光源是EUV光刻机的核心部件, 其原理是基于纳秒脉冲激光轰击锡液滴靶产生的等离子体辐射发光. EUV光源本质是一种流体光源, 涉及丰富而复杂的流体力学基本问题, 跨越从皮秒到毫秒的四个特征时间尺度. 本文综述了面向EUV光源的实验流体力学研究进展. 首先根据靶的类型, 分别介绍了射流、液滴和液膜靶的生成与调控基本原理和技术路线. 之后对三种靶与激光相互作用过程的特征时刻与典型现象进行了梳理, 重点放在各个特征时间尺度内激光轰击液滴靶的研究进展, 总结了不同参数激光脉冲轰击后靶的推进、变形和破碎规律. 最后对EUV光源中值得重点关注的实验流体力学关键问题进行了总结和展望, 提出改善激光等离子体EUV光源稳定性、亮度和寿命需要从以下三方面持续开展研究: 高频率、小直径、长间距液滴靶串的精准生成和调控, 激光辐照产生等离子体的膨胀和辐射规律, 以及液滴靶变形破碎机理和碎屑抑制、收集及清洁技术.

EUV /  激光 /  实验流体力学 / Abstract: The extreme ultraviolet (EUV) source is the enabling component of the EUV lithography. The commercialized EUV source is based on laser produced plasma from tin droplet target. EUV source is essentially a fluid-state light source, which involves rich and complex fundamental fluid mechanics problems with four characteristic time scales ranging from picoseconds to milliseconds. This review surveys the research progress of experimental fluid dynamics for EUV sources. First, the fundamental and technical aspects of the generation and control of jet, droplet and liquid film targets are introduced. Second, the dynamic response of the three types of targets to pulsed lasers were summarized, with an emphasis on droplet targets. Finally, in order to improve the stability, brightness and life the EUV sources, three key research topics in experimental fluid mechanics worthy of attention are proposed: (i) the precise generation and manipulation of fine tin droplet targes with long spacing at high frequencies; (ii) the quantitative physical picture of the expansion and radiation of the laser produced plasma, and (iii) the deformation and fragmentation mechanism of droplet targets and suppression, collection and cleaning technologies for debris.

Key words: EUV /  laser /  experimental fluid mechanics /  plasma  (a) 激光轰击水滴后得到的四种不同的液滴破碎模态 (时间单位为μs): (i)雾化模态 (atomization), 液滴半径186 μm, 激光能量4.9 mJ; (ii)不稳定液膜模态 (unstable sheet), 液滴半径401 μm, 激光能量2.7 mJ, 黑色箭头指向液膜破碎形成的孔洞; (iii)稳定液膜模态 (stable stretched sheet), 液滴半径450 μm, 激光能量0.6 mJ; (iv)粗破裂模态 (coarse fragmentation), 液滴半径1419 μm, 激光能量2.2 mJ. (b) 水滴的不同破碎模态总结,横轴是动压与拉普拉斯压力之比, 纵轴是无量纲化气泡能量 (通过激光脉冲能量转化得到), 四种模态的标志分别是: 雾化模态 (◆), 稳定液膜模态(▲), 不稳定液膜模态 (●)和粗破裂模态 (■). (c) 激光轰击超声悬浮液滴后内部的空化气泡和激波: (i)实验现象, 侧视图, 激光能量2.2 mJ, (ii)模拟结果, 侧视图, (iii)模拟结果, 俯视图, (iv)激波传播过程中产生的压力最低的环形区域, 图中时间单位为μs ( Gonzalez-Avila & Ohl 2016 )

能量分布为高斯分布的激光光斑轰击液滴后, 液滴形变动能与总动能之比和光斑大小 (以高斯分布特征参数 σ 表示, σ 越小, 光斑越小) 的关系. 模拟得到的 σ = π/8 (i-iv)和 σ = π/4 (v-viii)两种不同大小高斯光斑轰击液滴后的压力分布及液膜铺展情况: (i, v) 轰击后早期 ( t ≤ τ _e ) 液滴内部的等压线; (ii, vi) 液滴坐标系下的速度场( t / τ _c $ \ll $ We ^−1/2 ); (iii, vii)和(iv, viii)分别展示了在 t / τ _c = 0.0021 (iii), 0.013 (iv), 0.021 (vii)和0.064 (viii)时的液膜形态. 蓝色虚线是理论分析解, 红色实线是模拟结果( Gelderblom等 2016 )

作者材质直径( D )/μm频率/kHz速度/(m·s ⁻¹ )间距/μm间距/直径 Richardson等 ( 2004 )锡 ~ 35100200 ~ 115 ~ 3Mizoguchi等 ( 2010 )锡6010 ~ 14060721.2Rollinger等 ( 2011 )锡35 ~ 5820 ~ 1008 ~ 12280 ~ 4648Vinokhodov等 ( 2016d )锡-铟30 ~ 9020 ~ 1504 ~ 151802 ~ 6Kawasuji等 ( 2017 )锡2050 ~ 10045 ~ 90>900>45Luo等 ( 2023 )锡53 ~ 84>1510 ~ 15378 ~ 7989 ~ 19ASML锡16 ~ 140(27)>80—323 ~ 150056 Vinokhodov A Y, Koshelev K N, Krivtsun V M, et al. 2016b. Formation of a fine-dispersed liquid-metal target under the action of femto- and picosecond laser pulses for a laser-plasma radiation source in the extreme ultraviolet range. Quantum Electronics , 46 : 23-28. doi: 10.1070/QE2016v046n01ABEH015867 Vinokhodov A Y, Krivokorytov M S, Sidelnikov Y V, et al. 2016c. Droplet-based, high-brightness extreme ultraviolet laser plasma source for metrology. Journal of Applied Physics , 120 : 163304. doi: 10.1063/1.4966930 Vinokhodov A Y, Krivokorytov M S, Sidelnikov Y V, et al. 2016d. High brightness EUV sources based on laser plasma at using droplet liquid metal target. Laser-Plasma Source of EUV Radiation , 46 : 473. Weber C. 1931. Zum Zerfall eines Flüssigkeitsstrahles. ZAMM - Zeitschrift für Angewandte Mathematik und Mechanik , 11 : 136-154.

地址：北京海淀区北四环西路15号（100190） 电话：010-62637035 邮箱： lxjz@cstam.org.cn

北京仁和汇智信息技术有限公司