Microscopy of extreme ultraviolet lithography masks with 13.2 nm tabletop laser illumination

We report the demonstration of a reflection microscope that operates at 13.2 nm wavelength with a spatial resolution of 55+/-3 nm. The microscope uses illumination from a tabletop extreme ultraviolet laser to acquire aerial images of photolithography masks with a 20 s exposure time. The sample used for the initial demonstration of this EUV microscope consisted of Ni grating and elbow patterns printed onto a Mo/Si multilayer coated 2.5$\times $2.5 cm square Si wafer. Patterns with half-pitch sizes ranging from 80 nm to 500 nm were successfully printed onto the Mo/Si coated sample. The modulation transfer function of the optical system was characterized and these results constitute a first step toward the realization of table-top actinic microscopes for EUVL mask inspection.