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Proceedings Paper

Photoabsorption spectra of a laser produced Sn plasma
Author(s): M. Lysaght; D. Kilbane; A. Cummings; N. Murphy; P. Dunne; G. O'Sullivan; L. Gaynor; P. van Kampen; J. T. Costello; E. T. Kennedy
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Paper Abstract

The search for a source of EUV radiation for photolithography in the 13.5 nm region has been narrowed down to laser produced or pulsed discharge plasmas containing either xenon or tin. Higher conversion efficiencies can however be obtained with tin based plasmas within this wavelength regime. It is known that EUV photoabsorption by the lower ion stages of xenon reduces the photon flux from a xenon source. This is due to shape resonances from 4d-epsilonf transitions within Xe I-IV. The corresponding resonances for Sn I-IV have been obtained by means of the dual laser plasma (DLP) technique. It is also found that above the 4d ionisation threshold the spectra of Sn I-IV are dominated by a 4d-epsilonf shape resonance which peaks at close to 65 eV in each case. A transfer of oscillator strength from the shape resonance to pseudo-discrete 4d→nf transitions with increasing ionisation is clearly evident. Hartree-Fock with configuration interaction and relativistic time dependent local density approximation calculations successfully account for this behaviour and also permit identification of the discrete features.

Paper Details

Date Published: 3 June 2005
PDF: 8 pages
Proc. SPIE 5826, Opto-Ireland 2005: Optical Sensing and Spectroscopy, (3 June 2005); doi: 10.1117/12.604674
Show Author Affiliations
M. Lysaght, Univ. College Dublin (Ireland)
D. Kilbane, Dublin City Univ. (Ireland)
A. Cummings, Univ. College Dublin (Ireland)
N. Murphy, Univ. College Dublin (Ireland)
P. Dunne, Univ. College Dublin (Ireland)
G. O'Sullivan, Univ. College Dublin (Ireland)
L. Gaynor, Univ. College Dublin (Ireland)
P. van Kampen, Dublin City Univ. (Ireland)
J. T. Costello, Dublin City Univ. (Ireland)
E. T. Kennedy, Dublin City Univ. (Ireland)


Published in SPIE Proceedings Vol. 5826:
Opto-Ireland 2005: Optical Sensing and Spectroscopy
Gerard D. O'Sullivan; Brian D. MacCraith; Hugh James Byrne; Enda McGlynn; Alan G. Ryder, Editor(s)

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