First principles modelling of nucleation and growth during atomic layer deposition onto III-V substrates

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dc.contributor.advisor Elliott, Simon D. en Klejna, Sylwia 2014-02-05T15:04:01Z 2015-02-06T05:00:05Z 2013 2013
dc.identifier.citation Klejna, S. 2013. First principles modelling of nucleation and growth during atomic layer deposition onto III-V substrates. PhD Thesis, University College Cork. en
dc.identifier.endpage 151
dc.description.abstract Atomic layer deposition (ALD) is now used in semiconductor fabrication lines to deposit nanometre-thin oxide films, and has thus enabled the introduction of high-permittivity dielectrics into the CMOS gate stack. With interest increasing in transistors based on high mobility substrates, such as GaAs, we are investigating the surface treatments that may improve the interface characteristics. We focus on incubation periods of ALD processes on III-V substrates. We have applied first principles Density Functional Theory (DFT) to investigate detailed chemistry of these early stages of growth, specifically substrate and ALD precursor interaction. We have modelled the ‘clean-up’ effect by which organometallic precursors: trimethylaluminium (TMA) or hafnium and titanium amides clean arsenic oxides off the GaAs surface before ALD growth of dielectric commences and similar effect on Si3N4 substrate. Our simulations show that ‘clean-up’ of an oxide film strongly depends on precursor ligand, its affinity to the oxide and the redox character of the oxide. The predominant pathway for a metalloid oxide such as arsenic oxide is reduction, producing volatile molecules or gettering oxygen from less reducible oxides. An alternative pathway is non-redox ligand exchange, which allows non-reducible oxides (e.g. SiO2) to be cleaned-up. First principles study shows also that alkylamides are more susceptible to decomposition rather than migration on the oxide surface. This improved understanding of the chemical principles underlying ‘clean-up’ allows us to rationalize and predict which precursors will perform the reaction. The comparison is made between selection of metal chlorides, methyls and alkylamides precursors. en
dc.description.sponsorship Science Foundation Ireland (07/SRC/I1172) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2013, Sylwia Klejna en
dc.rights.uri en
dc.subject III-V substrate en
dc.subject ALD precursor en
dc.subject High-k dielectrics en
dc.subject Reducible oxide en
dc.subject Clean-up effect en
dc.subject Atomic layer deposition en
dc.subject Metal alkylamide en
dc.subject Ligand decomposition en
dc.subject Density functional theory (DFT) en
dc.subject.lcsh Chemical vapor deposition en
dc.subject.lcsh Density functionals en
dc.title First principles modelling of nucleation and growth during atomic layer deposition onto III-V substrates en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD (Science) en
dc.internal.availability Full text available en
dc.description.version Accepted Version
dc.contributor.funder Science Foundation Ireland en
dc.description.status Not peer reviewed en Chemistry en Tyndall National Institute en
dc.check.reason This thesis is due for publication or the author is actively seeking to publish this material en
dc.check.opt-out Not applicable en
dc.thesis.opt-out false
dc.check.entireThesis Entire Thesis Restricted
dc.check.embargoformat E-thesis on CORA only en
dc.internal.conferring Autumn Conferring 2013 en

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© 2013, Sylwia Klejna Except where otherwise noted, this item's license is described as © 2013, Sylwia Klejna
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