Microscope imaging system and method for emulating a high aperture imaging system, particularly for mask inspection

摘要

The present invention is directed to an optical imaging system for inspection microscopes with which lithography masks can be checked for defects particularly through emulation of high-aperture scanner systems. The microscope imaging system for emulating high-aperture imaging systems comprises imaging optics, a detector and an evaluating unit, wherein polarizing optical elements are selectively arranged in the illumination beam path for generating different polarization states of the illumination beam and/or in the imaging beam path for selecting different polarization components of the imaging beam, an optical element with a polarization-dependent intensity attenuation function can be introduced into the imaging beam path, images of the mask and/or sample are received by the detector for differently polarized beam components and are conveyed to the evaluating unit for further processing. With the proposed solution, it is possible in particular to examine lithography masks for defects by means of inspection microscopes in spite of increasingly smaller structures and increasingly higher image-side numerical apertures of the imaging systems. Realistic images of the scanner systems can be generated by emulating the occurring vector effects.