A ReaxFF Molecular Dynamics Study of Hydrogen Diffusion in Ruthenium-The Role of Grain Boundaries.

Ruthenium (Ru) thin films are used as protective caps for the multilayer mirrors in extreme ultraviolet lithography machines. When these mirrors are exposed to atomic hydrogen (H), it can permeate through Ru, leading to the formation of hydrogen-filled blisters on the mirrors. H has been shown to exhibit low solubility in bulk Ru, but the nature of H diffusion through Ru and its contribution to the mechanisms of blistering remain unknown.

Tin deposition on ruthenium and its influence on blistering in multi-layer mirrors.

An atomistic description of tin deposition on ruthenium and its effect on blistering damage is of great interest in extreme ultraviolet (EUV) lithography. In EUV machines, tin debris from the EUV-emitting tin plasma may be deposited on the mirrors in the optical path. Tin facilitates the formation of hydrogen-filled blisters under the ruthenium top layer of the multi-layer mirrors.

Hydrogen diffusion out of ruthenium-an ab initio study of the role of adsorbates.

Hydrogen permeation into mirrors used in extreme ultraviolet lithography results in the formation of blisters, which are detrimental to reflectivity. An understanding of the mechanism via which hydrogen ends up at the interface between the top ruthenium layer and the underlying bilayers is necessary to mitigate the blistering damage. In this study, we use density functional theory to examine the ways in which hydrogen, having entered the near-surface interstitial voids, can migrate further into the metal or to its surface.