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Proceedings Paper

Evaluating scanner lens spherical aberration using scatterometer
Author(s): Changan Wang; Gary Zhang; Colin L. Tan; Chris Atkinson; Mark A. Boehm; Jay M. Brown; David Godfrey; Michael E. Littau; Christopher J. Raymond
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Paper Abstract

Lens spherical error is an important lens aberration used to characterize lens quality and also has a significant contribution to across chip line width variation (ACLV). It also impacts tool-to-tool matching efforts especially when the optical lithography approaches sub-half wavelength geometry. Traditionally, spherical error is measured by using CD SEM with known drawbacks of poor accuracy and long cycle time. At Texas Instruments, an in-house scatterometer-based lens fingerprinting technique (ScatterLith) performs this tedious job accurately and quickly. This paper presents across slit spherical aberration signatures for ArF scanners collected using this method. The technique can successfully correlate these signatures with Litel lens aberration data and Nikon OCD data for spherical aberration errors as small as 10mλ. ACLV contributions from such small spherical errors can be quantified using this method. This provides the lithographer with an important tool to evaluate, qualify and match advanced scanners to improve across chip line width variation control.

Paper Details

Date Published: 26 June 2003
PDF: 9 pages
Proc. SPIE 5040, Optical Microlithography XVI, (26 June 2003); doi: 10.1117/12.485437
Show Author Affiliations
Changan Wang, Texas Instruments Inc. (United States)
Gary Zhang, Texas Instruments Inc. (United States)
Colin L. Tan, Texas Instruments Inc. (United States)
Chris Atkinson, Texas Instruments Inc. (United States)
Mark A. Boehm, Texas Instruments Inc. (United States)
Jay M. Brown, Nikon Precision Inc. (United States)
David Godfrey, Nikon Precision Inc. (United States)
Michael E. Littau, Accent Optical Technologies, Inc. (United States)
Christopher J. Raymond, Accent Optical Technologies, Inc. (United States)

Published in SPIE Proceedings Vol. 5040:
Optical Microlithography XVI
Anthony Yen, Editor(s)

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