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Proceedings Paper

Prediction of the lens lifetime by monitoring lens degradation on laser-based microlithography tools
Author(s): Albert Michaeli; Eylon Rosner; Yehuda Root; Hagay Duenias; Shai Rubin
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Paper Abstract

The bulk stability of the lens material in Deep-UV lithography (Fused Silica and Calcium Fluoride), as well as the susceptibility of the lens anti-reflection coating to a thin layer of chemical contamination during laser irradiation over long period of time, are the keys for advanced lithography systems lifetime. Lens degradation impacts laser-based exposure systems’ performance and therefore affects the product quality. There is a need for careful monitoring and prediction of lens lifetimes. This paper describes a method to calculate the degradation rate of optics and the lifetime prediction of these systems, along with some possible mechanisms for imaging degradation and factors that accelerate the degradation process. Currently, 'Pulse count' methods are used for such calculation; here we describe a new 'Energy based' method equal to 'Cumulative energy' through the projection lens. The paper compares the two methods using actual cases and shows the benefits of using the proposed method. We also suggest some new ways to deal with the problem. In addition, we report the learning from a project which entails developing a software application for automatic continuous tracking of degradation rates as well as the lens lifetime prediction across all Intel's laser based lithography tools.

Paper Details

Date Published: 12 May 2004
PDF: 10 pages
Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2004); doi: 10.1117/12.613278
Show Author Affiliations
Albert Michaeli, Intel Corp. (Israel)
Eylon Rosner, Intel Corp. (Israel)
Yehuda Root, Intel Corp. (Israel)
Hagay Duenias, Intel Corp. (Israel)
Shai Rubin, Intel Corp. (Israel)

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

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