Copper diffusion and mechanical toughness at Cu-silica interfaces glued with polyelectrolyte nanolayers

D. D. Gandhi, A. P. Singh, M. Lane, M. Eizenberg, G. Ramanath*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

We demonstrate the use of polyallylamine hydrochloride (PAH)-polystyrene sulfonate (PSS) nanolayers to block Cu transport into silica. Cu/PSS-PAH/ SiO2 structures show fourfold enhancement in device failure times during bias thermal annealing at 200 °C at an applied electric field of 2 MV/cm, when compared with structures with pristine Cu-SiO2 interfaces. Although the bonding at both Cu-PSS and PAH-SiO2 interfaces are strong, the interfacial toughness measured by the four-point bend tests is ∼2 Jm-2. Spectroscopic analysis of fracture surfaces reveals that weak electrostatic bonding at the PSS-PAH interface is responsible for the low toughness. Similar behavior is observed for Cu-SiO2 interfaces modified with other polyelectrolyte bilayers that inhibit Cu diffusion. Thus, while strong bonding at Cu-barrier and barrier-dielectric interfaces may be sufficient for blocking copper transport across polyelectrolyte bilayers, strong interlayer molecular bonding is a necessary condition for interface toughening. These findings are of importance for harnessing MNLs for use in future device wiring applications.

Original languageEnglish
Article number084505
JournalJournal of Applied Physics
Volume101
Issue number8
DOIs
StatePublished - 2007
Externally publishedYes

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