Patent ID: 9176072
Filing Date: 2015-11-03
Classification: G01N

Abstract:
1. A dark field inspection system comprising: three or more beam shaping paths for generating a composite, focused illumination line on a wafer, each beam shaping path for illuminating the wafer at an oblique angle, the beam shaping paths forming a ring illumination, wherein each of the beam shaping paths includes an independent light source positioned to result in independent, random noise at a surface of the wafer and wherein each independent light source provides incoherent light with respect to each other independent light source, wherein each of the plurality of beam shaping paths includes a cylindrical lens, each cylindrical lens being tilted and rotated with respect to a light beam from its corresponding light source, and wherein each cylindrical lens has a cylindrical axis positioned parallel to an illumination line, an optical axis, and a b-axis perpendicular to both the cylindrical axis and the optical axis, wherein the b-axis is positioned perpendicular to the light beam from its corresponding light source; an objective lens for capturing scattered light from the wafer; and an imaging sensor for receiving an output of the objective lens.