Decomposition of metal alkylamides, alkyls, and halides at reducible oxide surfaces: mechanism of 'clean-up' during atomic layer deposition of dielectrics onto III-V substrates

Show simple item record Klejna, Sylwia Elliott, Simon D. 2016-03-08T17:13:19Z 2016-03-08T17:13:19Z 2014-02-21
dc.identifier.citation KLEJNA, S. & ELLIOTT, S. D. 2014. Decomposition of Metal Alkylamides, Alkyls, and Halides at Reducible Oxide Surfaces: Mechanism of ‘Clean-up’ During Atomic Layer Deposition of Dielectrics onto III–V Substrates. Chemistry of Materials, 26, 2427-2437. en
dc.identifier.volume 26 en
dc.identifier.issued 7 en
dc.identifier.startpage 2427 en
dc.identifier.endpage 2437 en
dc.identifier.issn 0897-4756
dc.identifier.doi 10.1021/cm403336c
dc.description.abstract The pairing of high-k dielectric materials with high electron mobility semiconductors for transistors is facilitated when atomic layer deposition (ALD) is used to deposit the dielectric film. An interfacial cleaning mechanism (‘clean-up’) that results in consumption of semiconductor native oxides and in practically sharp dielectric/semiconductor interfaces has been observed during ALD of Al2O3, HfO2, TiO2, and Ta2O5 with various degrees of success. We undertake a comprehensive study using density functional theory (DFT) to explain differences in the performance of various classes of precursor chemicals in removing native oxide from III-V substrates. The study covers the metals Ta(V), Ti(IV), Zr(IV), Hf(IV), Al(III), Mg(II) combined with methyl, amide, and chloride ligands. Of these, we show that clean-up is most effective when depositing MgO. Clean-up with metal alkylamides has a similar mechanism to clean-up with metal methyls insofar as oxygen is scavenged by the metal. The difference in operation of alkylamide and methyl ligands lies in the affinity of the ligand to the substrate. Alkylamide is shown to be prone to decomposition rather than the migration of the entire ligand evinced by methyl. We investigate the multistep chemical processes associated with decomposition of alkylamide. These processes can also occur during later cycles of high-k ALD and give a chemical vapor deposition (CVD) component to the ALD process. These transformations lead to formation of clean-up products such as aziridine, ethene, N-methyl methyleneimine, hydrogen cyanide, and methane. Some - but not all - of the reactions lead to reduction of surface As2O3 (i.e., clean-up). These results explain the experimentally observed accumulation of metallic arsenic and arsenic suboxide at the interface. Such understanding can help achieve control of oxide-semiconductor interfaces through the appropriate choice of chemical precursor. en
dc.description.sponsorship Science Foundation Ireland (SFI grant No. 07/SRC/I1172 (FORME)); Higher Education Authority (SFI/HEA Irish Centre for High End Computing (ICHEC)) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher American Chemical Society en
dc.rights © 2014 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Chemistry of Materials, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see en
dc.subject Arsenic en
dc.subject Chemical vapor deposition en
dc.subject Chlorine compounds en
dc.subject Deposition en
dc.subject Dielectric films en
dc.subject Ethylene en
dc.subject Hafnium oxides en
dc.subject Ligands en
dc.subject Metal halides en
dc.subject Tantalum oxides en
dc.subject Chemical precursors en
dc.subject Chemical vapor depositions en
dc.subject CVD en
dc.subject Dielectric/semiconductor interface en
dc.subject High electron mobility en
dc.subject High-k dielectric materials en
dc.subject Hydrogen Cyanide en
dc.subject Oxide-semiconductor interfaces en
dc.subject ALD en
dc.subject Atomic layer deposition en
dc.title Decomposition of metal alkylamides, alkyls, and halides at reducible oxide surfaces: mechanism of 'clean-up' during atomic layer deposition of dielectrics onto III-V substrates en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother Simon Elliott, Tyndall Theory Modelling & Design Centre, University College Cork, Cork, Ireland. +353-21-490-3000 Email: en
dc.internal.availability Full text available en 2015-04-13T15:43:52Z
dc.description.version Accepted Version en
dc.internal.rssid 283617570
dc.contributor.funder Higher Education Authority en
dc.contributor.funder Science Foundation Ireland en
dc.description.status Peer reviewed en
dc.identifier.journaltitle Chemistry of Materials en
dc.internal.copyrightchecked Yes 12 month embargo. !!CORA!! AV+12 month embargo+set statement. en
dc.internal.licenseacceptance Yes en
dc.internal.IRISemailaddress en

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