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Studies the phenomenon of electromigration-induced edge drift in a finite, Al-Cu thin-film conductor using a one-dimensional diffusion model. Causes of edge drift; Grain boundaries; Electromigration diffusivity; Formation of precipitate-free zone at the cathode.

This letter reports the observation of the space charge limited current (SCLC) induced by injection and drift of Cu ions into porous low-k dielectrics. The SCLC, characterized by the momentary rise and fall of current with time, is found in all Cu interconnects having defective Ta barrier while it is absent in interconnects with intact barrier. This observation, combined with existing model on SCLC, leads to the conclusion that Cu ions can be injected through defects in Ta barrier and drift under electric field with the mobility as high as an order of 10-13 cm2/sec V at room temperature. [ABSTRACT FROM AUTHOR]

This letter presents a step-mode voltammetry method which uses ion diffusivity to characterize pore structure in both dense and porous low dielectric constant materials (low k) in patterned interconnect structures. Findings reveal that the intramolecular space in dense low k acts like a small physical pore network. It is determined that electrolyte ions can migrate through such space in dense low k, but with higher activation energy than in porous low k or the bulk solution, 0.31 eV vs 0.18–0.19 eV. Also, this study finds that the pores in ultralow k are not stable but can either coalesce or collapse depending on stress conditions. [ABSTRACT FROM AUTHOR]

This letter presents evidence of an oxidation-driven failure mechanism in Cu interconnects integrated with ultralow-κ materials. It is found that the open pore structure of ultralow-κ materials allows oxidants in the ambient to reach the interconnect structure and induce oxidation of Cu. In contrast to a normal oxidation process where Cu is in contact with the oxidant, oxidation is controlled by the outdiffusion of Cu through the barrier layers, Ta and SiCN, to form Cu oxide in the pores of the dielectric material. The loss of Cu by outdiffusion induces extensive voiding and subsequent failure in Cu interconnects. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]