中国物理B ›› 2026, Vol. 35 ›› Issue (7): 75203-075203.doi: 10.1088/1674-1056/ae74c1

• • 上一篇    

Spatiotemporal pulse-shaping effects on 4-μm laser-driven Sn microdroplet plasmas for extreme ultraviolet emission

Qi Min(敏琦)1,2,†, Chunbo Miao(苗春波)1, Hongyu Liu(刘宏宇)1, Xingbang Liu(刘兴邦)1, Haidong Lu(卢海东)1, Maogen Su(苏茂根)1,2,‡, and Chenzhong Dong(董晨钟)1,2,§   

  1. 1 Key Laboratory of Atomic and Molecular Physics & Functional Material of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;
    2 Gansu International Scientific and Technological Cooperation Base of Laser Plasma Spectroscopy, Lanzhou 730070, China
  • 收稿日期:2026-04-03 修回日期:2026-05-08 接受日期:2026-05-29 发布日期:2026-07-02
  • 通讯作者: Qi Min, Maogen Su, Chenzhong Dong E-mail:mq_lpps@nwnu.edu.cn;sumg@nwnu.edu.cn;dongcz@nwnu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 12474279 and 12374384), Science Fund for Distinguished Young Scholars of Gansu Province (Grant No. 26JRRA016), Provincial-level Youth Talent Individual Project of Gansu Province (Grant No. 2025QNGR15), and Youth Science and Technology Talent Innovation Project of Lanzhou City (Grant No. 2024-QN- 200).

Spatiotemporal pulse-shaping effects on 4-μm laser-driven Sn microdroplet plasmas for extreme ultraviolet emission

Qi Min(敏琦)1,2,†, Chunbo Miao(苗春波)1, Hongyu Liu(刘宏宇)1, Xingbang Liu(刘兴邦)1, Haidong Lu(卢海东)1, Maogen Su(苏茂根)1,2,‡, and Chenzhong Dong(董晨钟)1,2,§   

  1. 1 Key Laboratory of Atomic and Molecular Physics & Functional Material of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;
    2 Gansu International Scientific and Technological Cooperation Base of Laser Plasma Spectroscopy, Lanzhou 730070, China
  • Received:2026-04-03 Revised:2026-05-08 Accepted:2026-05-29 Published:2026-07-02
  • Contact: Qi Min, Maogen Su, Chenzhong Dong E-mail:mq_lpps@nwnu.edu.cn;sumg@nwnu.edu.cn;dongcz@nwnu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 12474279 and 12374384), Science Fund for Distinguished Young Scholars of Gansu Province (Grant No. 26JRRA016), Provincial-level Youth Talent Individual Project of Gansu Province (Grant No. 2025QNGR15), and Youth Science and Technology Talent Innovation Project of Lanzhou City (Grant No. 2024-QN- 200).

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摘要： Drive lasers near the 4-μm wavelength offer a fundamental thermodynamic advantage for extreme ultraviolet (EUV) lithography by optimally balancing laser absorption and in-band EUV opacity. Using radiation-hydrodynamics simulations, we investigate spatiotemporal pulse-shaping effects on 4-μm-driven Sn microdroplet plasmas under an industrially relevant overfill geometry. An energy-conserved full-factorial strategy evaluates the independent influences of pulse duration, temporal envelope, and transverse spatial profile. Results reveal that temporal and spatial shaping govern distinct physical processes. Temporally, box-shaped profiles establish a quasi-steady-state hydrodynamic regime that sustains optimal ionization, preventing the severe over-ionization of high-peak Gaussian pulses and the under-heating of extended low-power pulses. Spatially, although transverse intensity variations negligibly impact macroscopic energy absorption, angular emission analyses demonstrate that flat-top beams uniformly ablate the target periphery. This suppresses the optically thick peripheral plasma shroud inherent to Gaussian beams, thereby minimizing angle-dependent self-absorption and enhancing isotropic EUV photon escape. Ultimately, combining a 15-ns box-shaped temporal envelope with a spatial flat-top profile achieves a maximum conversion efficiency of 3.35%. Thus, optimizing EUV emission requires utilizing temporal shaping to sustain intrinsic emissivity and spatial flattening to minimize radiation transport losses.

关键词: laser-produced tin plasma, extreme ultraviolet lithography, 4-μm nanosecond laser, radiation-hydrodynamics simulation

Abstract: Drive lasers near the 4-μm wavelength offer a fundamental thermodynamic advantage for extreme ultraviolet (EUV) lithography by optimally balancing laser absorption and in-band EUV opacity. Using radiation-hydrodynamics simulations, we investigate spatiotemporal pulse-shaping effects on 4-μm-driven Sn microdroplet plasmas under an industrially relevant overfill geometry. An energy-conserved full-factorial strategy evaluates the independent influences of pulse duration, temporal envelope, and transverse spatial profile. Results reveal that temporal and spatial shaping govern distinct physical processes. Temporally, box-shaped profiles establish a quasi-steady-state hydrodynamic regime that sustains optimal ionization, preventing the severe over-ionization of high-peak Gaussian pulses and the under-heating of extended low-power pulses. Spatially, although transverse intensity variations negligibly impact macroscopic energy absorption, angular emission analyses demonstrate that flat-top beams uniformly ablate the target periphery. This suppresses the optically thick peripheral plasma shroud inherent to Gaussian beams, thereby minimizing angle-dependent self-absorption and enhancing isotropic EUV photon escape. Ultimately, combining a 15-ns box-shaped temporal envelope with a spatial flat-top profile achieves a maximum conversion efficiency of 3.35%. Thus, optimizing EUV emission requires utilizing temporal shaping to sustain intrinsic emissivity and spatial flattening to minimize radiation transport losses.

Key words: laser-produced tin plasma, extreme ultraviolet lithography, 4-μm nanosecond laser, radiation-hydrodynamics simulation

中图分类号:  (Plasma sources)

  • 52.50.Dg
52.20.-j (Elementary processes in plasmas) 52.25.-b (Plasma properties) 52.25.Os (Emission, absorption, and scattering of electromagnetic radiation ?) 52.65.-y (Plasma simulation)