MULTI-LAYER OVERLAY METROLOGY TARGET AND COMPLIMENTARY OVERLAY METROLOGY MEASUREMENT SYSTEMS

摘要

Multilayer overlay targets for use in imaging based metrology are disclosed. The overlay target includes a plurality of target structures, including three or more target structures, each target structure comprises a set of two or more pattern elements, and the target structure is configured to share a common center of symmetry upon alignment of the target structure , Each target structure is invariant with respect to the rotation of N degrees (N degrees is greater than 180 degrees) about a common center of symmetry, two or more pattern elements each have a separate center of symmetry, and two or more pattern elements of each target structure each It is invariant with respect to rotation of M degrees (M degrees are more than 180 degrees) with respect to individual symmetric centers.