Method and system for determining overlay tolerance

A method and system for determining overlay tolerances. The method comprises the steps of exposing wafers at different critical dimensions (preferably, above, below, and at optimum image size); and varying the overlay across each wafer, preferably by intentionally increasing the magnification. Funct...

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Bibliographische Detailangaben
Hauptverfasser:	NICHOLLS MATTHEW C, LEIDY ROBERT K, MILMORE TIMOTHY C
Format:	Patent
Sprache:	eng
Schlagworte:	APPARATUS SPECIALLY ADAPTED THEREFOR CINEMATOGRAPHY ELECTROGRAPHY GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS HOLOGRAPHY MATERIALS THEREFOR ORIGINALS THEREFOR PHOTOGRAPHY PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES,e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTORDEVICES PHYSICS TECHNICAL SUBJECTS COVERED BY FORMER USPC TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ARTCOLLECTIONS [XRACs] AND DIGESTS
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Beschreibung
Zusammenfassung:	A method and system for determining overlay tolerances. The method comprises the steps of exposing wafers at different critical dimensions (preferably, above, below, and at optimum image size); and varying the overlay across each wafer, preferably by intentionally increasing the magnification. Functional yield data are used to determine the overlay tolerance for each of the image sizes. The present invention, thus, studies the interaction of image size and feature misalignment. Prior to this invention, the only way to attain this information was to process a large number of lots and create a trend of image size and alignment vs. yield. The present invention solves the problem by determining the overlay tolerance based on yield data from a single lot. The design can then be altered or the overlay limit can be tightened (or relaxed) based on failure analysis of the regions/features that are most sensitive to misalignment.