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Proceedings Paper

Simulations of a SCALPEL wafer-heating correction using an adaptive Kalman filter
Author(s): Stuart T. Stanton
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Paper Abstract

The high-energy (100KeV) electron imaging process used by SCALPEL causes a dynamic heat load and wafer expansion response. Despite good thermal contact between the wafer and chuck, the dynamic distortion on a die length scale is too large to allow in the overlay error budget, and is fundamentally difficult to prevent or dissipate. However, the sub-field scanning strategy of SCALPEL allows us to implement a dynamic distortion-correction algorithm, by making a real-time position adjustment of the imaging sub-field. Analytical tools developed for understanding these phenomena could be applied in a purely predictive correction algorithm, in principle. However, these predictions are limited by the variability of chuck thermal contact, as well as by difficulty in handling the frictional chuck-attachment boundary condition. Hence, a means of improving upon a basic prediction is necessary to support a robust correction strategy. In this paper, I will explore the practical real-time implementation of a correction algorithm based on Adaptive Kalman Filter techniques, using dynamic alignment updates. Simulations demonstrate the feasibility of this approach to make a very close estimate of the ideal correction.

Paper Details

Date Published: 20 August 2001
PDF: 17 pages
Proc. SPIE 4343, Emerging Lithographic Technologies V, (20 August 2001); doi: 10.1117/12.436644
Show Author Affiliations
Stuart T. Stanton, Agere Systems (United States)

Published in SPIE Proceedings Vol. 4343:
Emerging Lithographic Technologies V
Elizabeth A. Dobisz, Editor(s)

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