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Title: Estimation of optimum density and temperature for maximum efficiency of tin ions in Z discharge extreme ultraviolet sources

Abstract

Extreme ultraviolet (EUV) discharge-based lamps for EUV lithography need to generate extremely high power in the narrow spectrum band of 13.5{+-}0.135 nm. A simplified collisional-radiative model and radiative transfer solution for an isotropic medium were utilized to investigate the wavelength-integrated light outputs in tin (Sn) plasma. Detailed calculations using the Hebrew University-Lawrence Livermore atomic code were employed for determination of necessary atomic data of the Sn{sup 4+} to Sn{sup 13+} charge states. The result of model is compared with experimental spectra from a Sn-based discharge-produced plasma. The analysis reveals that considerably larger efficiency compared to the so-called efficiency of a black-body radiator is formed for the electron density {approx_equal}10{sup 18} cm{sup -3}. For higher electron density, the spectral efficiency of Sn plasma reduces due to the saturation of resonance transitions.

Authors:
; ; ; ; ;  [1];  [2];  [2]
  1. Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
20982667
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 3; Other Information: DOI: 10.1063/1.2434987; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CHARGE STATES; ELECTRIC DISCHARGES; ELECTRON DENSITY; ELECTRON TEMPERATURE; EXTREME ULTRAVIOLET RADIATION; ION TEMPERATURE; LIGHT BULBS; PLASMA; PLASMA DENSITY; RADIANT HEAT TRANSFER; SPECTRA; TIN; TIN IONS

Citation Formats

Masnavi, Majid, Nakajima, Mitsuo, Hotta, Eiki, Horioka, Kazuhiko, Niimi, Gohta, Sasaki, Akira, Gotenba Division, Ushio, 1-90 Komakado, Gotenba, Shizuoka 412-0038, and Advanced Photon Research Center, Japan Atomic Energy Research Institute, Kyoto 619-0215. Estimation of optimum density and temperature for maximum efficiency of tin ions in Z discharge extreme ultraviolet sources. United States: N. p., 2007. Web. doi:10.1063/1.2434987.
Masnavi, Majid, Nakajima, Mitsuo, Hotta, Eiki, Horioka, Kazuhiko, Niimi, Gohta, Sasaki, Akira, Gotenba Division, Ushio, 1-90 Komakado, Gotenba, Shizuoka 412-0038, & Advanced Photon Research Center, Japan Atomic Energy Research Institute, Kyoto 619-0215. Estimation of optimum density and temperature for maximum efficiency of tin ions in Z discharge extreme ultraviolet sources. United States. doi:10.1063/1.2434987.
Masnavi, Majid, Nakajima, Mitsuo, Hotta, Eiki, Horioka, Kazuhiko, Niimi, Gohta, Sasaki, Akira, Gotenba Division, Ushio, 1-90 Komakado, Gotenba, Shizuoka 412-0038, and Advanced Photon Research Center, Japan Atomic Energy Research Institute, Kyoto 619-0215. Thu . "Estimation of optimum density and temperature for maximum efficiency of tin ions in Z discharge extreme ultraviolet sources". United States. doi:10.1063/1.2434987.
@article{osti_20982667,
title = {Estimation of optimum density and temperature for maximum efficiency of tin ions in Z discharge extreme ultraviolet sources},
author = {Masnavi, Majid and Nakajima, Mitsuo and Hotta, Eiki and Horioka, Kazuhiko and Niimi, Gohta and Sasaki, Akira and Gotenba Division, Ushio, 1-90 Komakado, Gotenba, Shizuoka 412-0038 and Advanced Photon Research Center, Japan Atomic Energy Research Institute, Kyoto 619-0215},
abstractNote = {Extreme ultraviolet (EUV) discharge-based lamps for EUV lithography need to generate extremely high power in the narrow spectrum band of 13.5{+-}0.135 nm. A simplified collisional-radiative model and radiative transfer solution for an isotropic medium were utilized to investigate the wavelength-integrated light outputs in tin (Sn) plasma. Detailed calculations using the Hebrew University-Lawrence Livermore atomic code were employed for determination of necessary atomic data of the Sn{sup 4+} to Sn{sup 13+} charge states. The result of model is compared with experimental spectra from a Sn-based discharge-produced plasma. The analysis reveals that considerably larger efficiency compared to the so-called efficiency of a black-body radiator is formed for the electron density {approx_equal}10{sup 18} cm{sup -3}. For higher electron density, the spectral efficiency of Sn plasma reduces due to the saturation of resonance transitions.},
doi = {10.1063/1.2434987},
journal = {Journal of Applied Physics},
number = 3,
volume = 101,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}
  • In order to investigate the plasma expansion behaviors and the electrical recovery process after the maximum implosion in our tin fueled laser-assisted discharge plasma (LDP) 13.5 nm EUV source, we developed and evaluated a cost-efficient spectroscopic method to determine the electron temperature T{sub e} and density n{sub e} simultaneously, by using Stark broadenings of two Sn II isolated lines (5s{sup 2}4f{sup 2}F{sup o}{sub 5/2} - 5s{sup 2}5d{sup 2}D{sub 3/2} 558.9 nm and 5s{sup 2}6d{sup 2}D{sub 5/2} - 5s{sup 2}6p{sup 2}P{sup o}{sub 3/2} 556.2 nm) spontaneously emitted from the plasma. The spatial-resolved evolutions of T{sub e} and n{sub e} of themore » expansion plasma over 50 to 900 ns after the maximum implosion were obtained using this modified Stark broadening method. According to the different n{sub e} decay characteristics along the Z-pinch axis, the expansion velocity of the electrons was estimated as {approx}1.2 x 10{sup 4} ms{sup -1} from the plasma shell between the electrodes towards the cathode and the anode. The decay time constant of n{sub e} was measured as 183 {+-} 24 ns. Based on the theories of plasma adiabatic expansion and electron-impact ionization, the minimum time-span that electrical recovery between the electrodes needs in order to guarantee the next succeeding regular EUV-emitting discharge was estimated to be 70.5 {mu}s. Therefore, the maximum repetition rate of our LDP EUV source is {approx}14 kHz, which enables the output to reach 125 W/(2{pi}sr).« less
  • The development and use of a single-fluid two-temperature approximated 2-D Magneto-Hydrodynamics code is reported. Z-pinch dynamics and the evolution of Magneto-Rayleigh-Taylor (MRT) instabilities in a gas jet type Extreme Ultraviolet (EUV) source are investigated with this code. The implosion and stagnation processes of the Z-pinch dynamics and the influence of initial perturbations (single mode, multi- mode, and random seeds) on MRT instability are discussed in detail. In the case of single mode seeds, the simulation shows that the growth rates for mm-scale wavelengths up to 4 mm are between 0.05 and 0.065 ns{sup −1}. For multi-mode seeds, the mode couplingmore » effect leads to a series of other harmonics, and complicates MRT instability evolution. For perturbation by random seeds, the modes evolve to longer wavelengths and finally converge to a mm-scale wavelength approximately 1 mm. MRT instabilities can also alter the pinch stagnation state and lead to temperature and density fluctuations along the Z axis, which eventually affects the homogeneity of the EUV radiation output. Finally, the simulation results are related to experimental results to discuss the mitigations of MRT instability.« less
  • The possibility of enhancing the conversion efficiency of a capillary-discharged xenon plasma via a current step is theoretically demonstrated using a simplified model. The current step is shown to exert a significant effect on the plasma dynamics in capillary discharge extreme ultraviolet sources. In particular, the pinching phase can be maintained at a quasi-steady-state by the current control, which prolongs the emission period of radiating plasma.
  • Conversion efficiencies (CEs) from incident laser energy to 13.5 nm light within a 2% bandwidth were measured with changing laser pulse durations for laser-produced tin plasmas. Experimental results indicate that the optimum pulse duration is determined by two parameters: one is the optical depth of tin plasma for 13.5 nm light and the other is laser absorption rate in 13.5 nm emission-dominant region. The maximum CE of 2.2% is obtained with pulse duration of 2.3 ns.
  • We report on the absolute sensitivity calibration of an extreme ultraviolet (XUV) spectrometer system that is frequently employed to study emission from short-pulse laser experiments. The XUV spectrometer, consisting of a toroidal mirror and a transmission grating, was characterized at a synchrotron source in respect of the ratio of the detected to the incident photon flux at photon energies ranging from 15.5 eV to 99 eV. The absolute calibration allows the determination of the XUV photon number emitted by laser-based XUV sources, e.g., high-harmonic generation from plasma surfaces or in gaseous media. We have demonstrated high-harmonic generation in gases andmore » plasma surfaces providing 2.3 {mu}W and {mu}J per harmonic using the respective generation mechanisms.« less