Overlay measurement based on moire effect between structured illumination and overlay target

A method and system for overly measurement is disclosed. The overlay measurement is performed based on moiré effect observed between structured illumination grids and overlay targets. A structured illumination is used to illuminate a first overlay target and a second overlay target. Upon obtaining a...

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Bibliographische Detailangaben
Hauptverfasser: MANASSEN AMNON, BOMZON ZEEV, LOEVSKY BARRY
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:A method and system for overly measurement is disclosed. The overlay measurement is performed based on moiré effect observed between structured illumination grids and overlay targets. A structured illumination is used to illuminate a first overlay target and a second overlay target. Upon obtaining an image of the first overlay target illuminated by the structured illumination and an image of the second overlay target illuminated by the structured illumination, relative displacement between the first overlay target and the structured illumination and relative displacement between the second overlay target and the structured illumination are measured. The overlay between the first overlay target and the second overlay target is then measured based on their relative displacements with respect to the structured illumination.