Mask three-dimensional effects of etched multilayer mask for 16-nm half-pitch in extreme ultraviolet lithography

摘要

The absorber stack on the conventional mask in extreme ultraviolet (EUV) lithography technology leads to mask three-dimensional (3-D) effects including horizontal-vertical (H-V) bias and position shifts through focus. To overcome these problems, we revisit the etched multilayer mask structure. We focus on the etched multilayer mask structure process down to a 16-nm half-pitch at a 0.33 numerical aperture, and we compare the results from this mask to those obtained with a conventional mask. Removing the absorber stack makes the H-V bias of an etched multilayer mask smaller than that of a conventional absorber mask for a 16-nm half-pitch. Thus, the etched multilayer mask can be used to reduce the mask 3-D effects.