Optical mask and method of correcting the same

摘要

An optical mask for a projection optical system and a method of correcting the mask wherein the mask includes a light intercepting pattern formed on a transparent substrate and a phase shifter for changing the phase of an exposure light provided at predetermined openings of the light intercepting pattern. An etching stopper film which transmits the exposure light is provided between said phase shifter and said light intercepting pattern and for correction of the mask a focused ion beam is utilized for removal of defects by the phase shifter.