Optimal determination of an overlay target using machine learning

A method comprising, by one or more processing circuitries:

• for each given overlay target of a plurality of different overlay targets to be manufactured on a semiconductor specimen, said given overlay target comprising a plurality of stacked semiconductor layers:
• obtaining a design image of the given overlay target, informative of geometry of the given overlay target, prior to manufacture of the given overlay target,
• feeding at least part of the design image to a trained machine learning model, to simulate at least one image of the given overlay target that would have been acquired by an electron beam examination system, prior to manufacture of the given overlay target,
• using the at least one image to determine, prior to manufacture of the given overlay target, data informative of at least one simulated overlay in the image, and
• using the data informative of the at least one simulated overlay of each given overlay target to select at least one optimal overlay target among the plurality of different overlay targets, wherein the at least one optimal overlay target is usable to be actually manufactured on the semiconductor specimen.

A non-transitory computer readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform:

• for each given overlay target of a plurality of different overlay targets to be manufactured on a semiconductor specimen, said given overlay target comprising a plurality of stacked semiconductor layers:
• obtaining a design image of the given overlay target, informative of geometry of the given overlay target, prior to manufacture of the given overlay target,
• feeding the design image to a trained machine learning model, to simulate at least one image of the given overlay target that would have been acquired by an electron beam examination system, prior to manufacture of the given overlay target,
• using the at least one image to determine, prior to manufacture of the given overlay target, data informative of at least one simulated overlay in the image, and
• using the data informative of the at least one simulated overlay of each given overlay target to select at least one optimal overlay target among the plurality of different overlay targets, wherein the at least one optimal overlay target is usable to be actually manufactured on the semiconductor specimen.