Show simple item record

dc.contributor.advisorEkerdt, John G.
dc.creatorElko-Hansen, Tyler Don-Michelen
dc.date.accessioned2014-09-16T20:15:44Zen
dc.date.issued2014-05en
dc.date.submittedMay 2014en
dc.identifier.urihttp://hdl.handle.net/2152/25917en
dc.descriptiontexten
dc.description.abstractElectrolessly deposited CoWP capping layers have been demonstrated to effectively reduce electromigration of Cu at the interconnect/dielectric-barrier cap interface while reducing resistivity relative to SiCN. However, as device dimensions scale, the need for alternative methods for the selective deposition of sub-5 nm, ultrathin, conformal Co capping layers is apparent. To develop methods for area-selective atomic layer deposition (AS-ALD) of Co caps for next-generation Cu interconnects, the ALD behavior of bis(N-tert-butyl-N’-ethylpropionamidinato) cobalt(II) (CoAMD) is evaluated on Cu, SiO₂, and a porous low-k ( ~2.6) dielectric, CDO. The first and second ALD half reactions of CoAMD on the respective substrates is evaluated with H₂ coreactant by adsorbing the precursor on the substrates under ALD cycling conditions at 265 °C with and without coreactant exposure. The adsorption studies indicate that CoAMD preferentially deposits most on Cu and least on CDO. Further, CoAMD, like other amidinate precursors, readily dissociates on the Cu transition metal surface but the ultimate per-cycle coverage is self-limited by the slow desorption of amidinate ligands and fragments from the Cu surface. Co films deposited by ALD from CoAMD on Cu at 265 °C indicate that Co burrows into the lower energy Cu surface as the film grows in order to reduce the free surface energy. The Cu remains as a surfactant-like layer on the topmost Co surface up to film thicknesses of at least 16 nm. Moreover, considerable intermixing at the Co/Cu interface and Cu concentration several nm into the Co films are observed indicating high surface mobility of the two materials and Cu diffusion at polycrystalline Co grain boundaries. Finally, employing low-tempurature ALD and selectively passivating the dielectric surfaces with OH targeting passivants leads to enhanced selectivity of CoAMD for deposition on Cu versus SiO₂ and CDO. Depositing Co from CoAMD on Cu and CDO at 165 °C after 500 kTorr-s exposure to trimethylchlorosilane at 50 °C leads to a 30:1 preference for Co accumulation on Cu, a twelve times improvement compared to deposition on cleaned Cu and CDO at 265 °C.en
dc.format.mimetypeapplication/pdfen
dc.language.isoenen
dc.subjectALDen
dc.subjectCobalten
dc.subjectCopperen
dc.subjectCDOen
dc.subjectArea-selectiveen
dc.subjectPassivationen
dc.titleSurface chemistry considerations for enhanced vapor deposition of metalsen
dc.typeThesisen
dc.date.updated2014-09-16T20:15:44Zen
dc.description.departmentChemical Engineeringen
thesis.degree.departmentChemical Engineeringen
thesis.degree.disciplineChemical Engineeringen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record