Multi-scale modelling of atomic layer deposition

Simple item page
dc.check.embargoformatNot applicableen
dc.check.infoNo embargo requireden
dc.check.opt-outNot applicableen
dc.check.reasonNo embargo requireden
dc.check.typeNo Embargo Required
dc.contributor.advisorElliott, Simon D.en
dc.contributor.authorShirazi, Mahdi
dc.contributor.funderScience Foundation Irelanden
dc.date.accessioned2014-03-05T15:46:49Z
dc.date.available2014-03-05T15:46:49Z
dc.date.issued2014
dc.date.submitted2014
dc.description.abstractHigh-permittivity ("high-k") dielectric materials are used in the transistor gate stack in integrated circuits. As the thickness of silicon oxide dielectric reduces below 2 nm with continued downscaling, the leakage current because of tunnelling increases, leading to high power consumption and reduced device reliability. Hence, research concentrates on finding materials with high dielectric constant that can be easily integrated into a manufacturing process and show the desired properties as a thin film. Atomic layer deposition (ALD) is used practically to deposit high-k materials like HfO2, ZrO2, and Al2O3 as gate oxides. ALD is a technique for producing conformal layers of material with nanometer-scale thickness, used commercially in non-planar electronics and increasingly in other areas of science and technology. ALD is a type of chemical vapor deposition that depends on self-limiting surface chemistry. In ALD, gaseous precursors are allowed individually into the reactor chamber in alternating pulses. Between each pulse, inert gas is admitted to prevent gas phase reactions. This thesis provides a profound understanding of the ALD of oxides such as HfO2, showing how the chemistry affects the properties of the deposited film. Using multi-scale modelling of ALD, the kinetics of reactions at the growing surface is connected to experimental data. In this thesis, we use density functional theory (DFT) method to simulate more realistic models for the growth of HfO2 from Hf(N(CH3)2)4/H2O and HfCl4/H2O and for Al2O3 from Al(CH3)3/H2O.Three major breakthroughs are discovered. First, a new reaction pathway, ’multiple proton diffusion’, is proposed for the growth of HfO2 from Hf(N(CH3)2)4/H2O.1 As a second major breakthrough, a ’cooperative’ action between adsorbed precursors is shown to play an important role in ALD. By this we mean that previously-inert fragments can become reactive once sufficient molecules adsorb in their neighbourhood during either precursor pulse. As a third breakthrough, the ALD of HfO2 from Hf(N(CH3)2)4 and H2O is implemented for the first time into 3D on-lattice kinetic Monte-Carlo (KMC).2 In this integrated approach (DFT+KMC), retaining the accuracy of the atomistic model in the higher-scale model leads to remarkable breakthroughs in our understanding. The resulting atomistic model allows direct comparison with experimental techniques such as X-ray photoelectron spectroscopy and quartz crystal microbalance.en
dc.description.sponsorshipScience Foundation Iteland (SFI FORME strategic research cluster 07/SRC/I1172)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationShirazi, M. 2014. Multi-scale modelling of atomic layer deposition. PhD Thesis, University College Cork.en
dc.identifier.endpage114
dc.identifier.urihttps://hdl.handle.net/10468/1427
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2014, Mahdi Shirazien
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectDFTen
dc.subjectKMCen
dc.subjectALDen
dc.subjectDensity functional theoryen
dc.subjectKinetic monte carloen
dc.subjectAtomic layer depositionen
dc.subject.lcshChemical vapor depositionen
dc.subject.lcshDensity functionalsen
dc.thesis.opt-outfalse
dc.titleMulti-scale modelling of atomic layer depositionen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Science)en
ucc.workflow.supervisorsimon.elliott@tyndall.ie
Files
Original bundle
Now showing 1 - 2 of 2
Thumbnail Image
Name:
ShiraziM_PhD2014.pdf
Size:
20.02 MB
Format:
Adobe Portable Document Format
Description:
Full Text E-Thesis
Download
Thumbnail Image
Name:
ShiraziM_abstract.pdf
Size:
60.51 KB
Format:
Adobe Portable Document Format
Description:
Abstract
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
5.62 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Doctoral Theses
College of Science, Engineering and Food Science - Doctoral Theses
Physics - Doctoral Theses
Tyndall National Institute - Doctoral Theses