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Proceedings Paper

Comparison of actinic lens characterization by aerial image evaluation and interferometric testing for 157-nm high-NA micro-objectives
Author(s): Horst Schreiber
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Paper Abstract

Focusing on smaller features for optical inspection or damage repair, smaller wavelengths are used to increase resolution or energy density. Objectives designed for 157nm will use calcium fluoride optics and the objectives need to be evaluated and optimized actinic, at wavelength. Measurement set-up and imaging results are presented through a catadioptric type of micro-objective. The set-ups and measurements are done at the 157nm wavelength as to include all actinic material effects. The imaging set-up uses a custom illuminator to image 130nm features, 500 times enlarged, onto a back-thinned CCD camera in real time. The knowledge of the spatial coherence characteristics of the light source together with the through-focus imaging of structures at various angles allows for the reconstruction of the wave aberrations of the lens. The lens is also measured and optimized using an interferometric set-up and phase shifting techniques.

Paper Details

Date Published: 24 May 2004
PDF: 10 pages
Proc. SPIE 5375, Metrology, Inspection, and Process Control for Microlithography XVIII, (24 May 2004); doi: 10.1117/12.533313
Show Author Affiliations
Horst Schreiber, Corning Tropel Corp. (United States)

Published in SPIE Proceedings Vol. 5375:
Metrology, Inspection, and Process Control for Microlithography XVIII
Richard M. Silver, Editor(s)

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