US Patent 7554656 Methods and systems for inspection of a wafer

Methods and systems for inspection of a wafer are provided. One method includes illuminating the wafer with light at a first wavelength that penetrates into the wafer and light at a second wafer that does not substantially penetrate into the wafer. The method also includes generating output signals responsive to light from the wafer resulting from the illuminating step. In addition, the method includes detecting defects on the wafer using the output signals. The method further includes determining if the defects are subsurface defects or surface defects using the output signals.