*Abdulrahman H. Basher¹, Marjan Krstic², Takae Takeuchi³, Tomoko Ito¹, Masato Kiuchi⁴, Kazuhiro Karahashi¹, Wolfgang Wenzel², Satoshi Hamaguchi¹¹Osaka University, Osaka, Japan; ²Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany; ³Nara Women’s University, Nara, Japan; ⁴National Institute of Advanced Industrial Science & Technology, Japan
Thermal Atomic layer etching (ALE) is one of the vital manufacturing technologies that is used to manufacture nano-scale electronic devices as it can be utilized for precise and damageless etching of substances. The goal of this study is to understand the mechanisms of surface chemical reactions during thermal ALE of a NiO surface with exposure to acacH molecules. The interaction of the acacH with a NiO surface is tested using the DFT simulation program TURBOMOLE. The embedded cluster method (ECM) is used to represent NiO surface models, which interact with acacH molecules as an etchant for its thermal ALE. We found that as an acacH molecule approaches a NiO surface, it is likely to deprotonate and the resulting acac- tends to bond with a Ni atom of the surface because of the highly ionic nature of NiO. In this way, volatile Ni(acac)₂ and H₂O can be formed when acacH molecules interact with a rough NiO surface. In some cases, we found that acacH can be decomposed on a NiO surface unlike hexafluoroacetylacetone (hfacH) molecules, and maybe because acach are less polarized than hfacH molecules. Reaction energies of such interactions have been evaluated from the simulations.