Patent ID: 8896832
Filing Date: 2014-11-25
Classification: G01N,G02B,G03F

Abstract:
1. An optical subsystem of a scatterometer, comprising: one or more light sources configured to produce light having different polarizations; a polarizing beam splitter configured to separate the light into two different light beams having orthogonal and mutually exclusive polarizations; two or more first optical elements configured to direct the two different light beams to a wafer; one or more second optical elements configured to control which one of the two different light beams illuminates the wafer during measurements; and a detection subsystem configured to separately detect two different scattered light beams resulting from illumination of the wafer with only the one of the two different light beams and to separately generate output responsive to the two different scattered light beams, wherein the two different scattered light beams have orthogonal and mutually exclusive polarizations, and wherein all optical surfaces of the optical subsystem used for the measurements are stationary during the measurements.