Patent ID: 6899982

Claim:
A method for the proper identification of photolithographic overlay data, the method comprising: providing a reticle having a plurality of alignment attributes that are encoded into a pattern that includes known deviations; imaging the reticle alignment attribute pattern onto a recording media of a projection system such that the known deviations are imaged in predetermined locations on the recording media and appear in a predetermined order when the projection system is operated in accordance with a properly ordered job deck, and the deviations include placement errors in the pattern of alignment attributes, wherein the placement errors include a removed portion of an attribute, located at the same position of the pattern of alignment attributes, inside each field point array; developing the image of the alignment attribute pattern on the recording media; measuring the alignment attribute pattern on the recording media with a programmed overlay tool; and determining if the overlay tool measured the alignment attribute pattern in a correct order by identifying the recording media locations of the known deviations within the measured pattern and comparing these locations to the encoded pattern.