Atomic layer etching process application to TaO hard-mask etching for next-generation EUV (Extreme-Ultraviolet) photomask fabrication

With pattern shrinkage of semiconductor devices, new etching process that can achieve accuracy less than 1 nm has been required for the next-generation EUV (Extreme-Ultraviolet) photomask fabrication. For this technological challenge, ALE (Atomic Layer Etching) could be a promising solution for nanofabrication of the next-generation EUV photomask. In this situation, we applied ALE process to etching hard-mask material, particularly Ta mono-oxide (TaO). In this study, we demonstrated the self-limiting etching of TaO hard-mask by optimizing ALE process condition.