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Proceedings Paper

Adaptive control of photolithography
Author(s): Oscar D. Crisalle; Robert A. Soper; Duncan A. Mellichamp; Dale E. Seborg
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Paper Abstract

Adaptive control techniques, with their capability for providing satisfactory control even when the process changes with time, are promising candidates for dealing with common problems encountered in photolithography processing such as batch-to-batch variations in resist properties, inconsistencies in resist curing, etc. In this paper an adaptive control strategy for the photolithography process is proposed and evaluated. The design utilizes a reduced-order lithography model, an on-line parameter estimator, and a nonlinear model-inversion controller (NMIC). The width of the printed resist lines--a crucial output of photolithography--is controlled by automatically adjusting the exposure energy. In the calculation of the appropriate exposure adjustment, the controller uses both measured critical dimensions as well as estimated values produced by the process model. The control system is capable of tracking changes in the photolithography process by automatic updating of key model parameters as the process evolves in time. Simulation studies of the closed-loop adaptive control strategy using the PROLITH simulation package to represent the lithography process demonstrate the feasibility of this approach.

Paper Details

Date Published: 1 July 1991
PDF: 19 pages
Proc. SPIE 1464, Integrated Circuit Metrology, Inspection, and Process Control V, (1 July 1991); doi: 10.1117/12.44462
Show Author Affiliations
Oscar D. Crisalle, Univ. of California/Santa Barbara (United States)
Robert A. Soper, Univ. of California/Santa Barbara (United States)
Duncan A. Mellichamp, Univ. of California/Santa Barbara (United States)
Dale E. Seborg, Univ. of California/Santa Barbara (United States)

Published in SPIE Proceedings Vol. 1464:
Integrated Circuit Metrology, Inspection, and Process Control V
William H. Arnold, Editor(s)

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