Surface inspection system and method using summed light analysis of an inspection surface

The present invention discloses methods of conducting surface inspections using summed light. One method includes the steps of measuring summed light intensity values for the substrate, generating comparison values for the substrate, and then comparing the measured summed light intensity values with the comparison values to determine whether there are defects in the substrate. In another embodiment, a method includes the steps of generating a reference cluster using measured summed light intensity values for selected portions of the inspection surface. Other summed light intensity values are measured and then compared with the reference cluster. Using this comparison, a determination is made as to whether a defect is present. Another embodiment uses a constant baseline signal which is compared to actual light intensity values to determine whether a substrate defect is present. In yet another embodiment a substrate is inspected for the presence of defects by conducting a pixel-by-pixel summed light inspection of the substrate.