Ablation dynamics of tin micro-droplet irradiated by double pulse laser used for extreme ultraviolet lithography source

D. Nakamura, T. Akiyama, K. Okazaki, K. Tamaru, A. Takahashi, T. Okada

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The ablation dynamics of a tin (Sn) micro-droplet by double pulse laser irradiation for the development of an extreme ultraviolet lithography source was investigated. The solid state Sn droplet target with a diameter of 30 νm was irradiated by double laser pulses from a Q-switched Nd : YAG laser and a CO2 laser, and the kinetic behaviour of debris such as Sn atoms, ions and of the dense particles from the droplet was investigated by the laser-induced fluorescence imaging method, Faraday cups and high-speed imaging, respectively. After the pre-pulse irradiation of the Nd : YAG laser, the ions were emitted towards the laser incident direction with an average kinetic energy of 3-6 keV and the dense particle cloud moved in the direction opposite to the laser incident direction with expansion by a reaction force due to the plasma expansion at a speed of approximately 500 m s-1. On the other hand, the Sn atoms were ejected in all directions from the target with a speed as fast as 20 km s-1. The expanding target was subsequently irradiated by the main pulse of the CO2 laser with a delay of 800 ns and the dense cloud almost disappeared due to main-pulse irradiation.

Original languageEnglish
Article number245210
JournalJournal of Physics D: Applied Physics
Volume41
Issue number24
DOIs
Publication statusPublished - 2008

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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