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Surface and structure analysis of ultrathin multilayer structures for copper diffusion studies
Author(s) -
Sun Y.M.,
Lee S. Y.,
Lemonds A.,
Lozano J.,
Zhou J.P.,
Ekerdt J. G.,
White J. M.,
Imesh I.
Publication year - 2001
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.1010
Subject(s) - x ray photoelectron spectroscopy , copper , tungsten , tantalum , annealing (glass) , diffusion barrier , tantalum nitride , analytical chemistry (journal) , transmission electron microscopy , secondary ion mass spectrometry , materials science , surface diffusion , chemistry , ion , chemical engineering , nanotechnology , metallurgy , layer (electronics) , organic chemistry , chromatography , adsorption , engineering
The development of ultrathin multilayer structures suitable for copper diffusion studies was investigated. The structures were examined by x‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS). Copper/barrier/SiO 2 /Si(100) and barrier/Cu/SiO 2 /Si(100) structures were fabricated on thermally grown SiO 2 by physical vapor deposition. Both tantalum and tungsten were chosen as the copper diffusion barrier and their thickness was held at <10 nm. For 2 nm of Cu on 10 nm of Ta, XPS showed steadily increasing Ta 4f and decreasing Cu 2p signals with annealing time at 400 °C, with changes occurring rapidly over the first 60 min and then much slower for the remaining time (up to 8 h). Cross‐sectional TEM indicated copper island formation on the tantalum surface. Copper islands were also found on tungsten films. For the reverse structure, W(5 nm)/Cu(700 nm)/SiO 2 /Si(100), no island formation was found after the thermal treatment. X‐ray photoelectron spectroscopy did detect a very weak Cu 2p signal after annealing for 8 h at 400 °C, which is equivalent to ∼0.2% copper bulk concentration in the tungsten barrier. Copyright © 2001 John Wiley & Sons, Ltd.