Reaction mechanism of the metal precursor pulse in plasma-enhanced atomic layer deposition of cobalt and the role of surface facets

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dc.check.date2021-05-15
dc.check.infoAccess to this article is restricted until 12 months after publication by request of the publisher.en
dc.contributor.authorLiu, Ji
dc.contributor.authorLu, Hongliang
dc.contributor.authorZhang, David Wei
dc.contributor.authorNolan, Michael
dc.contributor.funderScience Foundation Irelanden
dc.contributor.funderNational Natural Science Foundation of Chinaen
dc.contributor.funderHigher Education Authorityen
dc.contributor.funderIrish Centre for High-End Computingen
dc.date.accessioned2020-09-29T11:11:18Z
dc.date.available2020-09-29T11:11:18Z
dc.date.issued2020-05-15
dc.date.updated2020-09-29T11:00:57Z
dc.description.abstractCobalt is a potential candidate for replacing copper for interconnects and has been applied in the trenches and vias in the semiconductor industry. A non-oxidizing reactant is required in plasma-enhanced atomic layer deposition (PE-ALD) of thin films of metals to avoid O contamination. PE-ALD of Co has been demonstrated experimentally, but the growth mechanism and key reactions are not clear. In this paper, the reaction mechanism of metal cyclopentadienyl (Cp, C5H5) precursors (CoCp2) and NHx-terminated Co surfaces is studied by density functional theory calculations. The Cp ligands are eliminated by CpH formation via a hydrogen transfer step and desorb from the metal surface. The surface facet plays an important role in the reaction energies and activation barriers. The results show that on the NHx-terminated surfaces corresponding to ALD operating conditions (temperature range 550 K to 650 K), the two Cp ligands are eliminated completely on the Co(100) surface during the metal precursor pulse, resulting in Co atoms deposited on the Co(100) surface. However, the second Cp ligand reaction of hydrogen transfer is thermodynamically unfavorable on the Co(001) surface, resulting in CoCp fragment termination on the Co(001) surface. The final terminations after the metal precursor pulse are 3.03 CoCp/nm2 on the NHx-terminated Co(001) surface and 3.33 Co/nm2 on the NHx-terminated Co(100) surface. These final structures after the metal precursor pulse are essential to model the reaction during the following N-plasma step.en
dc.description.sponsorshipScience Foundation Ireland and National Natural Science Foundation of China ((SFI through the SFI-NSFC Partnership program, grant no. 17/NSFC/5279, NITRALD and the National Natural Science Foundation of China, grant no. 51861135105); Science Foundation Ireland and Higher Education Authority (SFI/HEA-funded Irish Centre for High End Computing (www.ichec.ie))en
dc.description.statusPeer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationLiu, J., Lu, H., Zhang, D. W. and Nolan, M. (2020) 'Reaction Mechanism of the Metal Precursor Pulse in Plasma-Enhanced Atomic Layer Deposition of Cobalt and the Role of Surface Facets', The Journal of Physical Chemistry C, 124(22), pp. 11990-12000. doi: 10.1021/acs.jpcc.0c02976en
dc.identifier.doi10.1021/acs.jpcc.0c02976en
dc.identifier.endpage12000en
dc.identifier.issn1932-7447
dc.identifier.issued22en
dc.identifier.journaltitleThe Journal Of Physical Chemistry Cen
dc.identifier.startpage11990en
dc.identifier.urihttps://hdl.handle.net/10468/10602
dc.identifier.volume124en
dc.language.isoenen
dc.publisherAmerican Chemical Societyen
dc.relation.urihttps://pubs.acs.org/doi/10.1021/acs.jpcc.0c02976
dc.rights© 2020 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry C copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.jpcc.0c02976en
dc.subjectAtomic layer depositionen
dc.subjectActivation energyen
dc.subjectAtomsen
dc.subjectCobalten
dc.subjectDensity functional theoryen
dc.subjectHydrogenen
dc.subjectLigandsen
dc.subjectSemiconductor device manufactureen
dc.titleReaction mechanism of the metal precursor pulse in plasma-enhanced atomic layer deposition of cobalt and the role of surface facetsen
dc.typeArticle (peer-reviewed)en
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