Patent ID: 8115926
Filing Date: 2012-02-14
Classification: G03F

Abstract:
1. An inspection apparatus configured to measure a property of a substrate, the inspection apparatus comprising: a radiation source configured to supply a plurality of polarized radiation beams comprising a first polarization direction and a second polarization direction; an optical element configured to focus the plurality of polarized radiation beams onto the substrate, such that the plurality of radiation beams reflect at a range of incident angles and at a range of azimuth angles; a fixed phase-shifter configured to retard the first polarization direction by a predetermined amount so as to impose a fixed phase shift on the plurality of polarized radiation beams; and a detector system configured to simultaneously detect an angle-resolved spectrum of the first and second polarization directions of the reflected plurality of polarized radiation beams for the range of incident angles and the range of azimuth angles.