Mrs Technology, Inc.

Azores Corporation

Mark S Lucas

Robert A McEachern

Craig R Simpson

Craig Simpson

Misalignment errors in a lithographic system resulting from the effect of environmental changes on the lens system itself are detected and corrected. A fiducial on the reticle adjacent to its working area is projected through the lens. A metrology plate carried by the lens holds reference mirrors and detectors. The reference mirrors receive the resultant image and reflect it to detectors in a reflected image plane. This provides feedback to the reticle alignment system as to the extent of misalignment, if any. Correction is made by moving the reticle until alignment is achieved and detected. This motion is achieved by using a reticle chuck with linear motors.

Reticle alignment system for use in lithography

Two lithographic substrate stages are used in a single lithographic system. While a substrate on one stage is being exposed, a second substrate is being loaded, unloaded, or aligned on a second stage. After exposure, the first stage is unloaded, reloaded, and the newly-loaded substrate is aligned, while the second substrate on the second stage is being exposed. The two stages are thus used alternately in different steps of the process. One of the steps is being performed on one stage while a different step is being performed on the other stage. The substrates on both stages are, therefore, being acted upon simultaneously. The two stages are carried on a single linear motor platen, and moved about the platen by use of linear motors. The two stages alternately both move in clockwise directions about the platen, or both move in counterclockwise directions. When both move in clockwise directions, the first stage is moving to the exposure position, and the second stage is moving to the unload/load/align station. When they both move in counterclockwise directions, the second stage is moving to the exposure position and the first stage is moving to the unload/load/align station.

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Groton, MA, United States of America

Mark S Lucas