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

TY - JOUR

T1 - Copper diffusion and mechanical toughness at Cu-silica interfaces glued with polyelectrolyte nanolayers

AU - Gandhi, D. D.

AU - Singh, A. P.

AU - Lane, M.

AU - Eizenberg, M.

AU - Ramanath, G.

N1 - Funding Information: This research is supported by grants from Istituti Ortopedici Rizzoli, Corrente'. The authors would like to thank Roberta Rambaldi and Chiara for the assistance in the

PY - 2007

Y1 - 2007

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=34247565622&partnerID=8YFLogxK

U2 - 10.1063/1.2717135

DO - 10.1063/1.2717135

M3 - 文章

AN - SCOPUS:34247565622

SN - 0021-8979

VL - 101

JO - Journal of Applied Physics

JF - Journal of Applied Physics

IS - 8

M1 - 084505

ER -