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Proceedings Paper

Why do weak acids not work in 193-nm photoresists?: matrix effects on acid-catalyzed deprotection
Author(s): Gerd Pohlers; George G. Barclay; Azher Razvi; Carolyne Stafford; Anthony Barbieri; James F. Cameron
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Paper Abstract

The present report investigates the chemical/physical parameters that influence chemically amplified photoresist deprotection chemistry. It was observed that the efficiency of the acid catalyzed deprotection chemistry used in chemically amplified photoresists is highly dependent on chemical environment. In the first part, a solution IR spectroscopic investigation was conducted on the deprotection kinetics of a model probe molecule, t-butyl phenyl carbonate, in a variety of solvents. The solvent used in this study where chosen to mimic the chemical composition of typical photoresist polymers used KrF and ArF lithography. It was observed that the activation energy of the deprotection of the probe molecule was strongly dependent upon the polarity and chemical nature of the model solvent systems investigated. In the second part, the probe molecule approach was modified so it can be used to study deprotection kinetics in actual resist films. Therefore, a novel, in-situ technique for monitoring acid-catalyzed deprotection in real-time via absorption spectroscopy was developed. Coumarin 338, which exhibits a significant change in the absorption spectrum upon loss of its t-butyl group, was used as probe molecule. This new methodology offers a number of advantages over existing techniques. The results obtained with this method show a similar dependence of the deprotection kinetics on the polarity of the matrix as those in solution.

Paper Details

Date Published: 14 May 2004
PDF: 15 pages
Proc. SPIE 5376, Advances in Resist Technology and Processing XXI, (14 May 2004); doi: 10.1117/12.537186
Show Author Affiliations
Gerd Pohlers, Shipley Co. LLC (United States)
George G. Barclay, Shipley Co. LLC (United States)
Azher Razvi, Shipley Co. LLC (United States)
Carolyne Stafford, Shipley Co. LLC (United States)
Anthony Barbieri, Shipley Co. LLC (United States)
James F. Cameron, Shipley Co. LLC (United States)

Published in SPIE Proceedings Vol. 5376:
Advances in Resist Technology and Processing XXI
John L. Sturtevant, Editor(s)

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