Patent ID: 9719920
Date: 2017-08-01
CPC Classifications: G01B,G01N,G03F

Claim:
1. A scatterometry measurement system, comprising: a scatterometry target having at least two layers and at least two periodic structures in which each periodic structure in the at least two periodic structures is disposed at a different layer and has a pitch; a detector; and an illumination source arranged to illuminate the scatterometry target with a first illumination beam at a first illumination angle and a second illumination beam at a second illumination angle to generate at least one diffracted order from each of the first illumination beam and the second illumination beam located entirely within a width of a numerical aperture of an imaging pupil plane, wherein at least one of the first illumination angle or the second illumination angle is outside of a plane defined by a grating direction and a normal to the scatterometry target such that the diffraction orders withinthe imaging pupil plane have a non-overlapping distribution.