Patent ID: 7554656

Claim:
A method for inspection of a wafer, comprising: illuminating the wafer with light at a first wavelength that penetrates into the wafer and light at a second wavelength that does not substantially penetrate into the wafer, wherein said illuminating comprises directing the light at the first and second wavelengths to the wafer at substantially the same angle of incidence; generating output signals responsive to light from the wafer resulting from said illuminating, wherein said generating comprises collecting and detecting the light from the wafer at multiple sets of solid angles; detecting defects on the wafer using the output signals; determining if the defects are subsurface defects or surface defects using the output signals; determining a lateral dimension of the subsurface defects using only the output signals corresponding to the light from the wafer at the first wavelength; and determining a lateral dimension of the surface defects using only the output signals corresponding to the light from the wafer at the second wavelength.