2002
DOI: 10.1063/1.1465107
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Formation of Cu diffusion channels in Ta layer of a Cu/Ta/SiO2/Si structure

Abstract: Three mechanisms for the formation of Cu diffusion channels in the Ta layer of a Cu/Ta/SiO2/Si structure are proposed. First, it is suggested that stacking faults formed during the recovery process induce localized regions of high internal energy in the Ta layer, from which Cu channels originate. Second, chemical reaction occurs at 800 °C and forms Ta4CuO11 across the Cu/Ta interface in Cu and Ta layers, which opens up channels for Cu diffusion. Third, triple junctions at the grain boundary of the Cu and Cu/Ta… Show more

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Cited by 21 publications
(10 citation statements)
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“…Analogous behavior has been reported for Cu-Ta films earlier. 33 However, the Cu-W films 24 have a better inhibition of Cu 3 Si growth than Cu-Mo because of its higher activation energy and shallow Cu depth profiles.…”
Section: Diffusion Processmentioning
confidence: 99%
“…Analogous behavior has been reported for Cu-Ta films earlier. 33 However, the Cu-W films 24 have a better inhibition of Cu 3 Si growth than Cu-Mo because of its higher activation energy and shallow Cu depth profiles.…”
Section: Diffusion Processmentioning
confidence: 99%
“…The thermal stability becomes rather more limited ͑Ͻ673 K͒ in the presence of a low partial pressure (Ͻ10 Ϫ2 mbar) of oxygen, due to interlayer oxidation. 10 The correspondence between XPS 27 and sheet resistance 28,29 indicates that the Cu/Ta/SiO 2 interface is more stable against thermal annealing than the Cu/Ta/Si-O-C interface characterized in this article, but that the thermal difference ͑ϳ800 K versus 900 K as a rough thermal limit͒ is hardly overwhelming, particularly since many low-dielectric constant materials may exhibit thermal decomposition or other changes in the mechanical properties in this temperature range. Neither XPS nor sheet resistance measurements, however, directly sample the diffusion of small amounts of Cu into the bulk dielectric substrate, and detailed currentvoltage and capacitance-voltage measurements would be of interest in this respect.…”
Section: Discussionmentioning
confidence: 73%
“…11 The thermal stability of the Cu/Ta-silicate interface is limited to Ͻ900 K in UHV conditions, due to the decomposition of the Ta silicate layer. 27 In contrast, electrical ͑sheet resistance͒ measurements 28,29 of Cu/Ta/SiO 2 annealed under oxygen-free conditions indicate a limiting temperature for interfacial stability of ϳ923 K ͑650°C͒. Above this temperature, interlayer diffusion and oxide formation result in degradation of the Cu sheet resistance.…”
Section: Discussionmentioning
confidence: 99%
“…7, but note that the current is higher when the electrode with higher Cu fraction (5Cu) is in anodic bias. Also, note that the peak potentials on the forward sweep appear in close proximity to the ideal potentials for reactions (2) and (3), but those for the reverse sweep appear at smaller potentials. Such a shift in the peak potentials does not indicate that the fundamental reactions are altered.…”
Section: Simulation Cell With Asymmetric Composite (Cu-ta) Electrodesmentioning
confidence: 69%
“…[1][2][3] At the same time, on-chip metrology capability is also facing challenges as new methods are needed to accommodate the increased complexity of the wiring levels. One area in particular, i.e., the ultrathin diffusion barrier (Ta), has been drawing much attention as the thickness of the barrier layer shrinks to a few nanometers (<2 nm after 2015).…”
Section: Introductionmentioning
confidence: 99%