Process for observing overlay errors on lithographic masks

摘要

A method of observing overlay errors associated with two masks or reticles includes providing alignment marks to a substrate. The alignment marks can be observed to determine overlay errors. In one embodiment, the lightness or darkness of the alignment marks can indicate an overlay error. The technique can be utilized in any photolithographic system including an EUV, VUV, DUV or conventional patterning device.