Abstract: A phase shift mask that corresponds to a layer of at least one semiconductor die has a substrate. A method thereof includes overlying a phase shifter film over the substrate. A permanent light calibration feature is positioned in close proximity to the at least one semiconductor die. The permanent light calibration feature has a predetermined area defined by an opening in the phase shifter film overlying the substrate. The predetermined area is within a range of area values and has a value that provides a light calibration value for use in testing with light for defects in the phase shift mask. An identification feature is positioned in close proximity to the permanent light calibration feature and is substantially larger than each of the permanent light calibration features. The identification feature provides a reference point to assist in locating a corresponding permanent light calibration feature.