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Proceedings Paper

Some aspects on mechanisms responsible for contamination of optical components in DUV lithographic exposure tools
Author(s): Hans Fosshaug; Mats Ekberg; Gunnar Kylberg
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Paper Abstract

Lithographic exposure tools in the deep-ultraviolet (DUV) region face challenges with contamination. Airborne molecular contamination is generally recognized as a severe threat in high-volume production of integrated circuits (ICs), and has recently also become of a concern in patterning of masks. When using high-energy photons at 248nm wavelength or lower, the risk of contamination may increase due to higher potential of breaking molecular bonds of organic species in the ambient of the optics. Especially resist outgassing during exposure may result in a build-up on the surface of the lens. The photodissociated molecules may readily deposit on the optics depending on the interaction between the contaminants and the lens surface and possibly cause a loss of transmission of light with time. Eventually the growth of the deposit will severely impact the throughput of the exposure tool, and in the worst case, necessitate a replacement of lens elements. Contamination control is therefore crucial for cost-effective DUV wafer and mask manufacturing. Trustworthy measurement methods as well as deep understanding of the mechanisms involved are of vital importance in order to understand and prevent molecular contamination. This paper discusses some of the factors influencing the deposition of hydrocarbon contaminants and also simulation work related to investigation of resist outgassing and contamination issues in the Sigma7300 laser pattern generator.

Paper Details

Date Published: 12 May 2005
PDF: 28 pages
Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2005); doi: 10.1117/12.600312
Show Author Affiliations
Hans Fosshaug, Micronic Laser Systems AB (Sweden)
Mats Ekberg, Micronic Laser Systems AB (Sweden)
Gunnar Kylberg, Kylberg Teknik (Sweden)

Published in SPIE Proceedings Vol. 5754:
Optical Microlithography XVIII
Bruce W. Smith, Editor(s)

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