CALIBRATED MEASUREMENT OF OVERLAY ERROR USING SMALL TARGETS

Abstract: a method for semiconductor metrology includes depositing first and second film layers on a substrate, patterning the layers to define a first target including a first feature in the first layer and a second feature in the second layer adjacent to the first feature, and a second target on the substrate including a first part, which is identical to the first target, and a second part adjacent to the first part such that the second overlay target has rotational symmetry of 180� around a normal to the substrate. the method further includes capturing and processing a first image of the second target to compute a calibration function based on the first and second parts of the target, and capturing and processing a second image of the first target while applying the calibration function to estimate an overlay error between the first and second film layers at the first location.

Inventor(s): Yoel Feler, Mark Ghinovker, Nir BenDavid, Yoram Uziel

CPC Classification: G03F7/70633 (PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices ; photosensitive materials or processes for photographic purposes ; electrophotography, sensitive layers or processes therefor ))

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