Fabrication of sub-10 nm lamellar structures by solvent vapour annealing of block copolymers

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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.advisorMorris, Michael A.en
dc.contributor.advisorHolmes, Justin D.en
dc.contributor.authorChaudhari, Atul
dc.contributor.funderScience Foundation Irelanden
dc.contributor.funderIntel Corporationen
dc.contributor.funderSemiconductor Research Corporation, United Statesen
dc.contributor.funderIntel Ireland Ltd.en
dc.date.accessioned2016-04-27T11:19:10Z
dc.date.available2016-04-27T11:19:10Z
dc.date.issued2015
dc.date.submitted2015
dc.description.abstractFabrication of nanoscale patterns through the bottom-up approach of self-assembly of phase-separated block copolymers (BCP) holds promise for nanoelectronics applications. For lithographic applications, it is useful to vary the morphology of BCPs by monitoring various parameters to make “from lab to fab” a reality. Here I report on the solvent annealing studies of lamellae forming polystyrene-blockpoly( 4-vinylpyridine) (PS-b-P4VP). The high Flory-Huggins parameter (χ = 0.34) of PS-b-P4VP makes it an ideal BCP system for self-assembly and template fabrication in comparison to other BCPs. Different molecular weights of symmetric PS-b-P4VP BCPs forming lamellae patterns were used to produce nanostructured thin films by spin-coating from mixture of toluene and tetrahydrofuran(THF). In particular, the morphology change from micellar structures to well-defined microphase separated arrangements is observed. Solvent annealing provides a better alternative to thermal treatment which often requires long annealing periods. The choice of solvent (single and dual solvent exposure) and the solvent annealing conditions have significant effects on the morphology of films and it was found that a block neutral solvent was required to realize vertically aligned PS and P4VP lamellae. Here, we have followed the formation of microdomain structures with time development at different temperatures by atomic force microscopy (AFM). The highly mobilized chains phase separate quickly due to high Flory-Huggins (χ) parameter. Ultra-small feature size (~10 nm pitch size) nanopatterns were fabricated by using low molecular weight PSb- P4VP (PS and P4VP blocks of 3.3 and 3.1 kg mol-1 respectively). However, due to the low etch contrast between the blocks, pattern transfer of the BCP mask is very challenging. To overcome the etch contrast problem, a novel and simple in-situ hard mask technology is used to fabricate the high aspect ratio silicon nanowires. The lamellar structures formed after self-assembly of phase separated PS-b-P4VP BCPs were used to fabricate iron oxide nanowires which acted as hard mask material to facilitate the pattern transfer into silicon and forming silicon nanostructures. The semiconductor and optical industries have shown significant interest in two dimensional (2D) molybdenum disulphide (MoS2) as a potential device material due to its low band gap and high mobility. However, current methods for its synthesis are not ‘fab’ friendly and require harsh environments and processes. Here, I also report a novel method to prepare MoS2 layered structures via self-assembly of a PS-b-P4VP block copolymer system. The formation of the layered MoS2 was confirmed by XPS, Raman spectroscopy and high resolution transmission electron microscopy.en
dc.description.sponsorshipSemiconductior Research Corporation, United States (Grant Number 2011-IN-2194; 09/SIRG/I1621)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationChaudhari, A. 2015. Fabrication of sub-10 nm lamellar structures by solvent vapour annealing of block copolymers. PhD Thesis, University College Cork.en
dc.identifier.endpage162en
dc.identifier.urihttps://hdl.handle.net/10468/2488
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2015, Atul Chaudhari.en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectBlock copolymeren
dc.subject2D nanomaterialsen
dc.subjectSelf-assemblyen
dc.subjectSolvent annealingen
dc.thesis.opt-outfalse
dc.titleFabrication of sub-10 nm lamellar structures by solvent vapour annealing of block copolymersen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Science)en
ucc.workflow.supervisorm.morris@ucc.ie
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