Patent ID: 8134709

Claim:
A method of aligning a substrate, the method comprising: setting an allowable alignment score that is used for determining non-identifications of a first alignment mark and a second alignment mark in one shot region of the substrate; setting a final allowable alignment score that is used for finally determining the non-identifications of the first alignment mark and the second alignment mark, the final allowable alignment score lower than the allowable alignment score; identifying the first alignment mark to obtain a first alignment score of the first alignment mark; comparing the first alignment score with the allowable alignment score; comparing the first alignment score with the final allowable alignment score, when the first alignment score is below the allowable alignment score; correcting a height of the substrate; comparing a first alignment score after correcting the height of the substrate with the final allowable alignment score; selectively identifying the second alignment mark to obtain a second alignment score of the second alignment mark, when the first alignment score is below the final allowable alignment score; comparing the second alignment score with the allowable alignment score; comparing the second alignment score with the final allowable alignment score, when the second alignment score is below the allowable alignment score; correcting the height of the substrate; comparing a second alignment score after correcting the height of the substrate with the final allowable alignment score; and aligning the substrate using the first alignment mark or the second alignment mark.