A trial semiconductor photomask design having discontinuity points is
provided, and each of the discontinuity points is treated as simulated
light sources. Simulated light from each of the simulated light sources
is focused, and a composite image intensity of the focused simulated
light is calculated to verify the trial semiconductor photomask design.
The trial semiconductor photomask design is sharpened. A photomask design
specification is generated for use in fabricating such a photomask.