Patent ID: 7327436

Claim:
A method for evaluating a local flare in an exposure tool, comprising: measuring a projection light intensity distribution on a semiconductor substrate by transferring a monitor mask pattern of an inspection photomask onto the semiconductor substrate, the monitor mask pattern being a window pattern surrounded by an opaque film; calculating a first ratio between an illumination light intensity at the monitor mask pattern and a first projection light intensity on the semiconductor substrate, the first projection light intensity calculated based on the monitor mask pattern; calculating a distribution function of a local flare, due to a mask pattern coverage of the monitor mask pattern, based on the first ratio and the projection light intensity distribution; dividing a design mask pattern of a target photomask into a plurality of unit areas; calculating a second ratio between the illumination light intensity on each of the unit areas and a second projection light intensity on the semiconductor substrate, the second projection light intensity calculated based on the design mask pattern; and calculating a local flare intensity in each of the unit areas, based on the second ratio and the distribution function.