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Proceedings Paper

Reduction of dose effects due to the transient absorption in fused silica at 193 nm
Author(s): Gregory J. Kivenzor; Richard J. Guerra
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Paper Abstract

This paper presents analysis, modeling, and test results of a 193 nm systems designed to minimize the dose effects due to the transient absorption (TA) in fused silica at 193 nm exposure. Fused silica is a material widely used to build optical systems for DUV lithography. Different types of fused silica have been subjected to thorough theoretical examination and testing in the leading laboratories of the world -- IBM Almaden Research Center, MIT Lincoln Labs, Laser-Laboratorium Gottingen and others. One of the most important effects discovered in some types of fused silica, was the TA demonstrated at 193 nm. Pulsed laser illumination may cause a substantial temporary decrease of the sample transmission. After the laser is shut off, the transmission recovers approximately to the initial value. Research results published over the last decade demonstrated that not only the magnitude of TA but also the time constant are functions of fluence. These transients can cause substantial dose variations, making the exposure process unstable and reducing the process yield. SVG manufactures high precision tools for critical-layers lithography where dose stability is crucial. Therefore, the TA was modeled and tested at the system level (laser illuminator and projection optics) to predict behavior of the optical elements in different exposure regimes. This paper presents the theoretical description of the behavior, results of computer simulation and testing for a multi-element system. Criteria of the systems engineering decisions allowing minimization of the TA impact on the dose control are discussed in the conclusion.

Paper Details

Date Published: 14 September 2001
PDF: 7 pages
Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001); doi: 10.1117/12.435739
Show Author Affiliations
Gregory J. Kivenzor, SVG Lithography Systems, Inc. (United States)
Richard J. Guerra, SVG Lithography Systems, Inc. (United States)

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

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