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

Basher, Abdulrahman H.; Krstić, Marjan 1; Fink, Karin ORCID iD icon 1; Ito, Tomoko; Karahashi, Kazuhiro; Wenzel, Wolfgang 1; Hamaguchi, Satoshi
1 Institut für Nanotechnologie (INT), Karlsruher Institut für Technologie (KIT)


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. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000124484
Veröffentlicht am 07.08.2021
Cover der Publikation
Zugehörige Institution(en) am KIT 3D Matter Made to Order (3DMM2O)
Institut für Nanotechnologie (INT)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 09.2020
Sprache Englisch
Identifikator ISSN: 0734-2101, 1520-8559
KITopen-ID: 1000124484
HGF-Programm 43.21.04 (POF III, LK 01) Molecular Engineering
Erschienen in Journal of vacuum science & technology / A
Verlag American Vacuum Society
Band 38
Heft 5
Seiten Art.Nr. 052602
Vorab online veröffentlicht am 06.08.2020
Nachgewiesen in Web of Science
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