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157 nm Pellicles for Photolithography: Mechanistic Investigation of the Deep UV Photolysis of Fluorocarbons

Kwangjoo Lee; Steffen Jockusch; Nicholas J. Turro; Roger H. French; Robert C. Wheland; Michael F. Lemon; Andre M. Braun; Tatjana Widerschpan; Paul Zimmerman

Title:
157 nm Pellicles for Photolithography: Mechanistic Investigation of the Deep UV Photolysis of Fluorocarbons
Author(s):
Lee, Kwangjoo
Jockusch, Steffen
Turro, Nicholas J.
French, Roger H.
Wheland, Robert C.
Lemon, Michael F.
Braun, Andre M.
Widerschpan, Tatjana
Zimmerman, Paul
Date:
Type:
Articles
Department:
Chemistry
Volume:
5377
Permanent URL:
Book/Journal Title:
Proceedings of SPIE
Abstract:
The advance of 157 nm as the next photolithographic wavelength has created a need to for transparent and radiation durable polymers for the use as pellicles. The most promising materials for the pellicles are fluorinated polymers, but the currently available fluorinated polymers undergo photodegradation and/or photodarkening upon exposure to 157 nm irradiation. To understand the mechanism of the photodegradation and photodarkening of fluorinated polymers, mechanistic studies on the photolysis of liquid model fluorocarbons such as, perfluoro butylethyl ether and perfluoro-2H-3-oxa-heptane, were performed employing UV, NMR, FTIR, GC, and GC/MS analysis. All hydrogen containing compounds showed decreased photostability compared to the fully perfluorinated compounds. Irradiation in the presence of atmospheric oxygen showed reduced photodarkening compared to deoxygenated samples. Irradiations were performed at 157 nm, 172 nm, 185 nm, and 254 nm and showed only minor wavelength dependence. Mechanisms for photodegradation of the fluorocarbons were proposed, where Rydberg excited states are involved.
Subject(s):
Chemistry
Publisher DOI:
10.1117/12.534381
Item views:
200
Metadata:
text | xml

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