Patent ID: 7150946

Claim:
A method for repairing a defect in a photolithographic mask for semiconductor patterning, the photolithographic mask having a substrate or first layer of a first material with a first thickness and a first light transmittance and a second layer of a second material having a second light transmittance differing from the first, the second layer being removable in at least one pre-selected region to form a pattern, the second layer, when intact, causing a selected phase shift in light waves that pass through it relative to light passing through the first layer or substrate alone, and, when absent in a region not a subset of the pattern, constituting the defect, the method for repairing said defect comprising the steps of: identifying the location of the defect; modifying said first thickness of said substrate or first layer in an area that includes said defect to a selected second thickness to introduce a pre-selected phase change in said area that includes the defect location; and depositing a repair material different than said first layer and having a pre-selected index of refraction to a selected thickness over said modified area of said first layer such that light passing through said deposited material having said selected thickness and said second thickness of said first layer has a phase shift substantially equal to said selected phase shift.