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

Chimaobi Mbanaso; Alin O. Antohe; Horace Bull; Gregory Denbeaux; Frank Goodwin; Ady Hershcovitch

doi:10.1117/1.JMM.11.2.021116

10 May 2012 Out-of-band radiation mitigation at 10.6 μm by molecular absorbers in laser-produced plasma extreme ultraviolet sources

Chimaobi Mbanaso, Alin O. Antohe, Horace Bull, Gregory Denbeaux, Frank Goodwin, Ady Hershcovitch

Author Affiliations +

Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 11, Issue 2, 021116 (May 2012). https://doi.org/10.1117/1.JMM.11.2.021116

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.

Citation Download Citation

Chimaobi Mbanaso, Alin O. Antohe, Horace Bull, Gregory Denbeaux, Frank Goodwin, and Ady Hershcovitch "Out-of-band radiation mitigation at 10.6 μm by molecular absorbers in laser-produced plasma extreme ultraviolet sources," Journal of Micro/Nanolithography, MEMS, and MOEMS 11(2), 021116 (10 May 2012). https://doi.org/10.1117/1.JMM.11.2.021116

Published: 10 May 2012

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

;

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE