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Abstract

A method for aligning wafer includes selecting a nun-defective wafer alignment mark of a first wafer loaded in an exposure apparatus, and storing non-defective wafer alignment marks as a gray level reference image. A plurality of wafer alignment marks of a loaded second wafer are stored. Each of the plurality of wafer alignment mark images of the second wafer are respectively compared with the reference image of the first wafer pixel by pixel to obtain matching value for each of the plurality of the wafer alignment mark images. Each of the plurality of values of the matching values are compared with a set minimum value. The wafer alignment mark image having the matching value smaller than the minimum value with the reference image is replaced. The alignment information for an underlying layer using a wafer alignment information for an underlying layer using a wafer alignment sensor is obtained.

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