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

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.