A system for defect simulation is provided. A defect layout generator
generates a defect layout comprising a given number of spot defects of a
given size. A processor first compares the defect layout and a provided
circuit layout comprising a plurality of conductive regions. The
processor further determines whether the spot defects are located on the
conductive regions, and determines whether short-circuits and/or open
circuits are caused by the spot defects in the conductive regions.