Patent ID: 8912495

Claim:
A system configured to detect defects in one or more structures formed on a wafer, comprising: an illumination subsystem configured to direct light in discrete spectral bands to the one or more structures formed on the wafer, wherein at least some of the discrete spectral bands are in a near infrared wavelength range, wherein each of the discrete spectral bands has a bandpass that is less than 100 nm, wherein the illumination subsystem comprises first and second apertures that are different from each other, and wherein the illumination subsystem is further configured to scan the light in the discrete spectral bands across the wafer using the first aperture and then the second aperture; a detection subsystem configured to generate output responsive to light in the discrete spectral bands reflected from the one or more structures; and a computer subsystem configured to detect defects in the one or more structures on the wafer using the output, wherein the computer subsystem is further configured to detect the defects in the one or more structures on the wafer using the output generated by scanning performed with the first and second apertures.