Design aided image reconstruction

A non-transitory computer-readable medium, storing program instructions executable on a computer system for performing a computer-implemented method for determining boundaries of one or more patterned features formed on a specimen from an unresolved image of the one or more patterned features on the specimen, wherein the computer-implemented method comprises:

• generating a difference image for one or more patterned features formed on a specimen by subtracting a reference image from an image generated by a detector for the one or more patterned features, wherein an inspection subsystem comprises at least an energy source and the detector, wherein the energy source is configured to generate energy that is directed to the specimen, wherein the detector is configured to detect energy from the specimen and to generate images responsive to the detected energy, and wherein the one or more patterned features formed on the specimen are unresolved in the images generated by the detector;
• comparing the difference image to different simulated images, wherein the different simulated images are generated by simulating difference images generated for the one or more patterned features formed on the specimen with different perturbations, respectively;
• based on results of the comparing, assigning an amplitude to each of the different perturbations;
• and
• determining one or more boundaries of the one or more patterned features formed on the specimen by applying the different perturbations to one or more designed boundaries of the one or more patterned features with the assigned amplitudes.

A computer-implemented method for determining boundaries of one or more patterned features formed on a specimen from an unresolved image of the one or more patterned features on the specimen, comprising:

• generating a difference image for one or more patterned features formed on a specimen by subtracting a reference image from an image generated by a detector for the one or more patterned features, wherein an inspection subsystem comprises at least an energy source and the detector, wherein the energy source is configured to generate energy that is directed to the specimen, wherein the detector is configured to detect energy from the specimen and to generate images responsive to the detected energy, and wherein the one or more patterned features formed on the specimen are unresolved in the images generated by the detector;
• comparing the difference image to different simulated images, wherein the different simulated images are generated by simulating difference images generated for the one or more patterned features formed on the specimen with different perturbations, respectively;
• based on results of the comparing, assigning an amplitude to each of the different perturbations;
• and
• determining one or more boundaries of the one or more patterned features formed on the specimen by applying the different perturbations to one or more designed boundaries of the one or more patterned features with the assigned boundaries, wherein said generating, said comparing, said assigning, and said determining are performed by one or more computer subsystems.