Patent attributes
An overlay mark formed on a photomask, comprising a first rectangular region, a second rectangular region, a third rectangular region, and a fourth rectangular region, each rectangular region having the same pattern configuration, a longer side of the first rectangular region and a longer side of the third rectangular region being parallel to each other, and a longer side of the second rectangular region and a longer side of the fourth rectangular region being parallel to each other, the longer side of the first rectangular region being perpendicular to the longer side of the second rectangular region; wherein each pattern configuration has at least two different pattern elements allowing other pattern elements be chosen to align when any one of the pattern elements on the substrate was damaged during process.
