Ion beam etching of new absorber materials for sub-5nm EUV masks

For future nodes, TaN-based absorber layers on EUV mask-blanks, may need to be replaced with thinner layers of new material systems. Ni and Co based materials are promising material candidates owing to their high EUV absorption. Ion Beam Etching (IBE) is being explored as an option for patterning these metallic systems that are hard to etch by Reactive Ion Etch. In this work we expand our initial work on the IBE of Ni absorber films to include the role of etch beam energy and alternative etch-masks for both Ni and Co based films. We present experimental film level data such as etch uniformity, angular-dependent etch rates, and surface roughness. We extend the modeling of IBE of line-space patterns, to narrower line widths and various etch-mask materials vis-a-vis side wall angle and CD fidelity, both as a function of beam energy and angle of etch.