As device geometries shrink to 0.25 micron and smaller, all facets of integrated circuit (IC) processing are being challenged. With device sizes shrinking, so too shrinks the size of a defect that can cause chip failure, and hence yield loss. Contamination free manufacturing practices are becoming critical for successful device fabrication. To accomplish this, elimination of defect sources has a high priority. A defect can be a particle, microcontamination, pattern anomaly, crystalline defect such as a stacking fault, and so on. Defects have become a main source of yield loss to the semiconductor industry. This comes at a time when 90% yield values on mature product cannot increase at the rate that has occurred in the past. The industry is now faced with finding methods of incremental yield increase, in-line, on production wafers. Automatic Defect Classification (ADC) is an important part of SEMATECH's strategy to meet these industry needs.