Spatial profiles of electron density, electron temperature, average ionic charge, and EUV emission of laser-produced Sn plasmas for EUV lithography

Yuta Sato, Kentaro Tomita, Syoichi Tsukiyama, Toshiaki Eguchi, Kiichiro Uchino, Kouichiro Kouge, Hiroaki Tomuro, Tatsuya Yanagida, Yasunori Wada, Masahito Kunishima, Takeshi Kodama, Hakaru Mizoguchi

Research output: Contribution to journalArticle

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Abstract

Spatial profiles of the electron density (ne), electron temperature (Te), 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 26μm 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 ne, Te, and Z clearly differed. However, under all plasma conditions, intense EUV was only observed at a sufficiently high Te (> 25 eV) and in an adequate ne range [1024-(2 × 1025)m-3]. These plasma parameters lie in the efficient-EUV light source range, as predicted by simulations.

Original languageEnglish
Article number036201
JournalJapanese Journal of Applied Physics
Volume56
Issue number3
DOIs
Publication statusPublished - Mar 1 2017

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Laser produced plasmas
Extreme ultraviolet lithography
Electron temperature
Carrier concentration
lithography
electron energy
Plasmas
profiles
lasers
Plasma sources
Lasers
Pulsed lasers
Conversion efficiency
Light sources
Thomson scattering
Scattering
pulsed lasers
Temperature
light sources
time measurement

All Science Journal Classification (ASJC) codes

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

Cite this

Spatial profiles of electron density, electron temperature, average ionic charge, and EUV emission of laser-produced Sn plasmas for EUV lithography. / Sato, Yuta; Tomita, Kentaro; Tsukiyama, Syoichi; Eguchi, Toshiaki; Uchino, Kiichiro; Kouge, Kouichiro; Tomuro, Hiroaki; Yanagida, Tatsuya; Wada, Yasunori; Kunishima, Masahito; Kodama, Takeshi; Mizoguchi, Hakaru.

In: Japanese Journal of Applied Physics, Vol. 56, No. 3, 036201, 01.03.2017.

Research output: Contribution to journalArticle

Sato, Yuta ; Tomita, Kentaro ; Tsukiyama, Syoichi ; Eguchi, Toshiaki ; Uchino, Kiichiro ; Kouge, Kouichiro ; Tomuro, Hiroaki ; Yanagida, Tatsuya ; Wada, Yasunori ; Kunishima, Masahito ; Kodama, Takeshi ; Mizoguchi, Hakaru. / Spatial profiles of electron density, electron temperature, average ionic charge, and EUV emission of laser-produced Sn plasmas for EUV lithography. In: Japanese Journal of Applied Physics. 2017 ; Vol. 56, No. 3.
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