Patent ID: 10228331

Abstract:
This system comprises an illumination optics subsystem for generating and directing an incident beam towards a defect on a surface of a wafer. The illumination optics subsystem includes a light source for generating the incident beam and one or more polarization components for adjusting a ratio and/or a phase difference for the incident beam's electric field components. The system includes a collection optics subsystem for collecting scattered light from the defect and/or surface in response to the incident beam, and the collection optics subsystem comprises an adjustable aperture at the pupil plane, a rotatable waveplate for adjusting a phase difference of electric field components of the collected scattered light, and a rotatable analyzer. The system includes a controller for selecting a polarization of the incident beam, obtaining a defect scattering map from the defect, obtaining a surface scattering map from the background surface, and determining a configuration of the polarization components, aperture mask, rotatable waveplate, and analyzer based on analysis of the defect and surface scattering map to maximize a defect signal to noise ratio.