Patent ID: 6984473

Claim:
A method of patterning a mask blank, the method comprising: applying to a light-blocking film of a mask blank a chemically amplified resist film comprising a photosensitive acid generator and a first resin, the photosensitive acid generator generating an acid upon irradiation with activating light or radiation, the first resin becoming soluble in a base by action of the acid in response to the activating light or radiation; applying a protective film on the chemically amplified resist film, the protective film comprising the photosensitive acid generator and a second resin, the second resin, after irradiation with the activating light or radiation, being soluble in a solvent that does not substantially dissolve the first resin; exposing the protective film and the chemically amplified resist film to patterned irradiation of the activating light or radiation; dissolving and removing the protective film of the mask blank from the chemically amplified resist film with a solvent that does not substantially dissolve the chemically amplified resist film of the mask blank; and developing the chemically amplified resist film to reproduce the patterned irradiation.