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Proceedings Paper

Protecting 248-nm and 193-nm lithography from airborne molecular contamination during semiconductor fabrication
Author(s): Anatoly Grayfer; Oleg P. Kishkovich; David Ruede
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Paper Abstract

Airborne molecular contamination monitoring and control historically meant filtration of molecular bases such as ammonia and NMP since the introduction of DUV processes at the 250 nm node. Until recently, equipment manufacturers and photoresist suppliers have primarily focused on molecular base induced resist degradation. Improvements in resist chemistries combined with new robust filtration and molecular base monitoring have allowed device manufacturers to process wafers with few concerns about yield loss due to T-topping and related resist problems. Today the industry has moved to the implementation of real-time molecular base monitoring for improved process control. As device manufacturers move production to 180 nm geometries and pilot lines develop 130 nm processes, issues of resist protection are joined by the potential degradation of lithography system optical components due to deposition of condensable organic molecules. This issue is of particular concern with the introduction of 193 nm exposure systems. The higher energy ArF source increases the probability of these and other contaminants reacting and forming films on exposed optical surfaces. Solutions for the KrF generation have already been extended and supplemented with a new generation of filtration and monitoring. As device geometries shrink, real-time molecular base monitoring is being introduced into photo tool enclosures to help process engineers better understand the impact of resist contamination relative to a few nanometers of shift in CD's and implement procedures to insure high yields are maintained and CD control is tightened. Powerful molecular base filtration complements the resist suppliers' efforts to improve resist sensitivity to molecular bases. In the latest exposure tools hybrid filtration is being introduced to remove condensable organic contaminants specifically to protect the costly optics used in 193 nm steppers and scanners. Studies have been conducted to extend filtration to include acidic species. Results of these programs are presented and potential solutions for future device generations are discussed.

Paper Details

Date Published: 14 September 2001
PDF: 9 pages
Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001); doi: 10.1117/12.435765
Show Author Affiliations
Anatoly Grayfer, Extraction Systems Inc. (United States)
Oleg P. Kishkovich, Extraction Systems Inc. (United States)
David Ruede, Extraction Systems Inc. (United States)

Published in SPIE Proceedings Vol. 4346:
Optical Microlithography XIV
Christopher J. Progler, Editor(s)

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