Patent ID: 7626691

Claim:
An apparatus for inspecting overlay patterns, comprising: an optical module which projects a plurality of neighboring overlay patterns formed on a wafer; a pickup unit which obtains a plurality of image signals corresponding to the plurality of overlay patterns projected from the optical module; a comparison unit including a database which provides at least one pre-stored overlay pattern image, the comparison unit configured to: generate a plurality of images including the plurality of overlay patterns from the image signals obtained at the pickup unit; compare an overlay pattern image corresponding to any one of the plurality of overlay patterns with the pre-stored overlay pattern image; and based on the comparison, extract at least a portion of the overlay pattern image identical or similar to the previously input overlay pattern image; a restoration unit which restores the extracted overlay pattern image in accordance with a predetermined overlay pattern; and a readout unit which calculates and compares a position of the restored overlay pattern image with a position of an overlay pattern image not compared by the comparison unit, and which reads out a deviation between the two positions.