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Proceedings Paper

Optimal model-predictive control of overlay lithography implemented in an ASIC fab
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Paper Abstract

This work integrates fundamental models and metrology sensors with state-of-the-art estimation and model-predictive control techniques in order to regulate overlay photo-lithography errors. Fundamental overlay models are presented that describe the relationship between the photo-lithography steppers and the metrology sensors. A Kalman Filter is employed that utilizes the process model and the sensor model and automatically estimates uncertain states given metrology measurements. A model-predictive controller is employed that is very effective in rejecting disturbances in the overlay process, such as tool drift and model mismatch. All overlay errors have been driven to zero +/- the measurement variance of the metrology tool. This level of control is achieved for every tool-device-layer-reticle combination.

Paper Details

Date Published: 1 July 2003
PDF: 12 pages
Proc. SPIE 5044, Advanced Process Control and Automation, (1 July 2003); doi: 10.1117/12.485303
Show Author Affiliations
Scott A. Middlebrooks, LSI Logic Corp. (United States)

Published in SPIE Proceedings Vol. 5044:
Advanced Process Control and Automation
Matt Hankinson; Christopher P. Ausschnitt, Editor(s)

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