Patent ID: 6897444

Claim:
A method of detecting defects in integrated circuit dies, the method comprising: directing a first incident beam to be incident on a multi-pixel imaging region from a first die; simultaneously detecting electrons emitted from a plurality of pixels within the multi-pixel imaging region; generating a first image data set comprising signal values representing image content of the plurality of pixels within the multi-pixel imaging region; directing a second incident beam to be incident on a corresponding multi-pixel imaging region from a second die; simultaneously detecting electrons emitted from a plurality of pixels within the corresponding multi-pixel imaging region; generating a second image data set comprising signal values representing image content of the plurality of pixels within the corresponding multi-pixel imaging region; storing the first and second image data sets in memory; determining a misalignment between the first and second image data sets with a resolution of a fraction of one pixel; aligning the image data sets by adjusting one of the image data sets to correct the misalignment; and comparing the aligned first and second image data sets to detect differences therebetween.