Patent ID: 7738692

Claim:
A method of determining a quality of a light source applied to a photolithographic process, comprising the steps of: exposing an image sensor array to a light from the light source; collecting addresses and respective intensities corresponding to a plurality of locations on a pupil map representing intensity of the light from the light source on the image sensor array; defining at least one of an inner curve and an outer curve of the pupil map based upon the collected addresses and respective intensities; and applying the light source to the photolithographic process for forming a device on a semiconductor wafer if at least one of the following conditions is satisfied: a radius of the inner curve having a distance defined from a center of the pupil map to an address corresponding to about 7.5% of a total sum intensity to about 12.5% of the total sum intensity, the total sum intensity for a given radius calculated as a sum of the collected intensities within the given radius, or the outer curve encloses points corresponding to addresses having between about 87.5% of the total sum intensity and about 92.5% of the total sum intensity.