US Patent 10190979 Metrology imaging targets having reflection-symmetric pairs of reflection-asymmetric structures

Metrology targets, design files, and design and production methods thereof are provided. Metrology targets comprising at least one reflection-symmetric pair of reflection-asymmetric structures are disclosed. The structures may or may not be periodic, may comprise a plurality of unevenly-spaced target elements, which may or may not be segmented. The asymmetry may be with respect to target element segmentation or structural dimensions. Also, target design files and metrology measurements of the various metrology targets are disclosed.