学術雑誌論文

学術雑誌論文

text

Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films. 2020, 38(5), p. 052602

Formation and desorption of nickel hexafluoroacetylacetonate Ni(hfac)2on a nickel oxide surface in atomic layer etching processes

AVS Science and Technology Society

英語

text

2020-09

https://doi.org/10.1116/6.0000293

Abdulrahman H. Basher, Marjan Krstić, Takae Takeuchi, Michiro Isobe, Tomoko Ito, Masato Kiuchi, Kazuhiro Karahashi1, Wolfgang Wenzel, and Satoshi Hamaguchi, Journal of Vacuum Science & Technology A 38:2, (2020); licensed under a Creative Commons Attribution (CC BY) license.

Thermal atomic layer etching (ALE) of nickel (Ni) may be performed with a step of thin-layer oxidation of its surface and another step of its removal by gas-phase hexafluoroacetylacetone (hfacH) as an etchant. In this study, adsorption of hfacH and possible formation of volatile nickel hexafluoroacetylacetonate Ni(hfac)2 on a NiO surface were investigated based on the density functional theory (DFT) with more realistic surface material models than those used in the previous study [A. H. Basher et al., J. Vac. Sci. Technol. A 38, 022610 (2020)]. It has been confirmed that an hfacH molecule approaching a NiO surface deprotonates without a potential barrier and adsorbs on the surface exothermically. In addition, stable adsorption of two deprotonated hfacH molecules on a NiO (100) surface was found to occur not on a single Ni atom but over a few Ni atoms instead, which makes the formation of a Ni(hfac)2 complex on the flat surface very unlikely even at elevated temperature. However, if the surface is rough and a Ni atom protrudes from the surrounding atoms, two hexafluoroacetylacetonate anions (hfac-) can bond to the Ni atom stably, which suggests a possibility of desorption of a Ni(hfac)2 complex from the surface at elevated temperature. Given the experimentally observed fact that desorption of Ni(hfac)2 complexes typically takes place on a NiO surface at a temperature of ∼300-400 °C, our DFT calculations indicate that the surface roughness of an oxidized Ni surface facilitates the formation and desorption of organometallic complexes Ni(hfac)2, and therefore, the resulting Ni surface after ALE can be smoother than the initial surface.

© 2020 Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License.

78314

Formation and desorption of nickel hexafluoroacetylacetonate Ni(hfac)2on a nickel oxide surface in atomic layer etching processes

AVS Science and Technology Society

英語

2020-09

Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films

38

5

052602

https://doi.org/10.1116/6.0000293

https://hdl.handle.net/11094/78314