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Journal of Micro/Nanolithography, MEMS, and MOEMS

Out-of-band radiation mitigation at 10.6 μm by molecular absorbers in laser-produced plasma extreme ultraviolet sources
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Paper Abstract

Out-of-band radiation in extreme ultraviolet (EUV) exposure tools remains one of the critical issues that must be addressed before the implementation of this lithography technique for high-volume manufacturing. The out-of-band spectrum at the intermediate focus of EUV sources that use a CO2 laser-produced plasma is dominated by scattered radiation from the drive laser, which operates near 10.6-μm wavelength. To reduce the unwanted heating of optical components in the exposure tool caused by the infrared wavelength, a 10.6-μm wavelength-absorbing gas can be used to reduce the number of photons at this wavelength reaching the intermediate focus. Gaseous sulfur hexafluoride (SF6), whose U3 infrared active mode is vibrationally excited by radiation around 10.6-μm wavelength, can be used to function as a molecular absorber and thus, mitigate part of the infrared radiation. In this work, the optical absorption of gaseous SF6 is experimentally investigated at the CO2 laser wavelengths close to 10.6 μm as well as the EUV wavelength. Various considerations affecting the use of a gas-based spectral filter are also discussed in this paper.

Paper Details

Date Published: 10 May 2012
PDF: 7 pages
J. Micro/Nanolith. 11(2) 021116 doi: 10.1117/1.JMM.11.2.021116
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 11, Issue 2
Show Author Affiliations
Chimaobi Mbanaso, College of Nanoscale Science & Engineering (United States)
Alin O. Antohe, College of Nanoscale Science & Engineering (United States)
Horace Bull, College of Nanoscale Science & Engineering (United States)
Gregory Denbeaux, College of Nanoscale Science & Engineering (United States)
Frank Goodwin, SEMATECH North (United States)
Ady Hershcovitch, Brookhaven National Lab. (United States)


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