Metrology overlay targets are provided, as well as method of monitoring process shortcomings. Targets comprise periodic structures, at least one of which comprising repeating asymmetric elements along a corresponding segmentation direction of the periodic structure. The asymmetry of the elements may be designed in different ways, for example as repeating asymmetric sub-elements along a direction perpendicular to the segmentation direction of the elements. The asymmetry of the sub-elements may be designed in different ways, according to the type of monitored process shortcomings, such as various types of hot spots, line edge shortening, process windows parameters and so forth. Results of the measurements may be used to improve the process and/or increase the accuracy of the metrology measurements.