Demonstration of 22-nm half pitch resolution on the SHARP EUV microscope

Abstract

The Semiconductor High-Numerical-aperture (NA) Actinic Reticle Review Project (SHARP) is an extreme ultraviolet (EUV)-wavelength, synchrotron-based microscope dedicated to advanced EUV photomask research. The instrument is designed to emulate current and future generations of EUV lithography (EUVL). The performance of the SHARP microscope has been well characterized for its low-NA lenses, emulating imaging in 0.25 and 0.33 NA lithography scanners. Evaluating the resolution of its higher-NA lenses, intended to emulate future generations of EUV lithography, requires a photomask with features down to 22-nm half pitch. The authors fabricated a sample with features down to 20-nm half pitch, exposing a wafer with a standard multilayer coating in the Berkeley microfield exposure tool, and used it to demonstrate real-space imaging down to 22-nm half pitch on the SHARP microscope. The demonstrated performance of SHARP's high-NA zoneplates, together with the extended capabilities of the tool, provide a platform that is available today, suited for research targeted at upcoming generations of EUVL many years into the future.