Optical observations of post-discharge phenomena of laser-triggered discharge produced plasma for EUV lithography

Soowon Lim, Seiya Kitajima, Peng Lu, Takashi Sakugawa, Hidenori Akiyama, Sunao Katsuki, Yusuke Teramoto

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

This paper reports the dynamic post-discharge phenomena of laser-triggered discharge-produced plasmas (LTDPP) for extreme ultraviolet lithography (EUVL) sources. A pulsed laser was focused on the high-voltage tin cathode surface to form tin vapor jet across a 5mm long anode- cathode gap, which leads to the electrical breakdown. The post-discharge phenomena were observed using both of the Schlieren method and high-speed camera. Schlieren images show the dynamic evolution of the discharge plasma and the development of tin droplets. Visible emission from the plasma lasted for more than 1 μs after the current stopped. The droplets emerged from the cathode approximately 100 μs after discharge and spread throughout the electrodes gap. Various sizes of droplets stagnate in the gap for milliseconds. The subsequent laser pulse and voltage application show an interaction between the droplets and the subsequent discharge. The subsequent laser pulse evaporates not only the cathode surface but also the droplets, which influence the tin vapor distribution in the gap. This uncertain vapor distribution affects the formation process of microplasmas that emit EUV.

Original languageEnglish
Article number01AA01
JournalJapanese journal of applied physics
Volume54
Issue number1 Supplement
DOIs
Publication statusPublished - 2015 Jan 1
Externally publishedYes

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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