Emission characteristics of debris from CO2 and Nd:YAG laser-produced tin plasmas for extreme ultraviolet lithography light source

Akihiko Takahashi, Daisuke Nakamura, K. Tamaru, T. Akiyama, T. Okada

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19 Citations (Scopus)

Abstract

We describe a comparative study of the emission characteristics of debris from CO2 and Nd:YAG laser-produced tin plasmas for developing an extreme-ultraviolet (EUV) lithography light source. Tin (Sn) ions and droplets emitted from a Sn plasma produced by a CO2 laser or an Nd:YAG laser were detected using Faraday cups and quartz crystal microbalance (QCM) detectors, respectively. The droplets were also monitored by using silicon substrates as witness plates. The results showed higher ion kinetic energy and lower particle emission for the CO2 laser than the Nd:YAG laser for the same laser energy (50 mJ). The average ion energy was 2.2 keV for the CO2 laser-produced plasma (LPP), and 0.6 keV for the Nd:YAG LPP. The debris accumulation of the CO2 LPP detected by the QCM detectors, however, was less than one fourth of that of the Nd:YAG LPP for the same laser energy. Using ion energy data, the mirror lifetime is estimated for the CO 2 and Nd:YAG lasers. In both cases, the upper limit of the number of shots was of the order of 106.

Original languageEnglish
Pages (from-to)73-77
Number of pages5
JournalApplied Physics B: Lasers and Optics
Volume92
Issue number1
DOIs
Publication statusPublished - Jul 1 2008

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debris
YAG lasers
tin
light sources
lithography
laser plasmas
quartz crystals
microbalances
lasers
ions
particle emission
energy
detectors
shot
kinetic energy
mirrors
life (durability)
silicon
crystals

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Physics and Astronomy (miscellaneous)

Cite this

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abstract = "We describe a comparative study of the emission characteristics of debris from CO2 and Nd:YAG laser-produced tin plasmas for developing an extreme-ultraviolet (EUV) lithography light source. Tin (Sn) ions and droplets emitted from a Sn plasma produced by a CO2 laser or an Nd:YAG laser were detected using Faraday cups and quartz crystal microbalance (QCM) detectors, respectively. The droplets were also monitored by using silicon substrates as witness plates. The results showed higher ion kinetic energy and lower particle emission for the CO2 laser than the Nd:YAG laser for the same laser energy (50 mJ). The average ion energy was 2.2 keV for the CO2 laser-produced plasma (LPP), and 0.6 keV for the Nd:YAG LPP. The debris accumulation of the CO2 LPP detected by the QCM detectors, however, was less than one fourth of that of the Nd:YAG LPP for the same laser energy. Using ion energy data, the mirror lifetime is estimated for the CO 2 and Nd:YAG lasers. In both cases, the upper limit of the number of shots was of the order of 106.",
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AU - Takahashi, Akihiko

AU - Nakamura, Daisuke

AU - Tamaru, K.

AU - Akiyama, T.

AU - Okada, T.

PY - 2008/7/1

Y1 - 2008/7/1

N2 - We describe a comparative study of the emission characteristics of debris from CO2 and Nd:YAG laser-produced tin plasmas for developing an extreme-ultraviolet (EUV) lithography light source. Tin (Sn) ions and droplets emitted from a Sn plasma produced by a CO2 laser or an Nd:YAG laser were detected using Faraday cups and quartz crystal microbalance (QCM) detectors, respectively. The droplets were also monitored by using silicon substrates as witness plates. The results showed higher ion kinetic energy and lower particle emission for the CO2 laser than the Nd:YAG laser for the same laser energy (50 mJ). The average ion energy was 2.2 keV for the CO2 laser-produced plasma (LPP), and 0.6 keV for the Nd:YAG LPP. The debris accumulation of the CO2 LPP detected by the QCM detectors, however, was less than one fourth of that of the Nd:YAG LPP for the same laser energy. Using ion energy data, the mirror lifetime is estimated for the CO 2 and Nd:YAG lasers. In both cases, the upper limit of the number of shots was of the order of 106.

AB - We describe a comparative study of the emission characteristics of debris from CO2 and Nd:YAG laser-produced tin plasmas for developing an extreme-ultraviolet (EUV) lithography light source. Tin (Sn) ions and droplets emitted from a Sn plasma produced by a CO2 laser or an Nd:YAG laser were detected using Faraday cups and quartz crystal microbalance (QCM) detectors, respectively. The droplets were also monitored by using silicon substrates as witness plates. The results showed higher ion kinetic energy and lower particle emission for the CO2 laser than the Nd:YAG laser for the same laser energy (50 mJ). The average ion energy was 2.2 keV for the CO2 laser-produced plasma (LPP), and 0.6 keV for the Nd:YAG LPP. The debris accumulation of the CO2 LPP detected by the QCM detectors, however, was less than one fourth of that of the Nd:YAG LPP for the same laser energy. Using ion energy data, the mirror lifetime is estimated for the CO 2 and Nd:YAG lasers. In both cases, the upper limit of the number of shots was of the order of 106.

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