Patent ID: 7718008

Claim:
A method for cleaning a photomask with a pellicle mounted, in which the pellicle has a pellicle frame and a pellicle film adhered on the upper surface of the pellicle frame and the pellicle frame has a gas introducing hole and a gas discharging hole, comprising: a step of introducing a gaseous substituting substance from the gas introducing hole in a pellicle inner space surrounded by the photo mask and the pellicle, substituting foreign substances on the photo mask with the substituting substance, and discharging the foreign substances form the gas discharging hole; and a step of irradiating an ultraviolet ray to the photo mask, while an air or a nitrogen gas or a rare gas is introduced from the gas introducing hole, for degrading the substituted substituting substance so as to be gaseous, and discharging the same from the gas discharging hole.