Physics insight and first-principles calculation of atomic conductance: implications for the future interconnects

There are still many unknowns and open questions concerning the properties of atomic wires, which can be very different from the bulk case. A physics-based compact model framework for analysis of atomic-scale conductors in the presence of point defects is described, and the results of the compact model are compared with First-principle DFT calculations. The calculations indicate that the typically more resistive bulk metals can emerge as lower-resistance options over Al and Cu at atomic dimensions. In the proposed model, the electrons are considered to be localized at their host atoms. The discussion topics include low-temperature resistance of atomic wires from different materials, and the influence of elementary point defects, such as atomic voids on electron transport. It is argued that the concept of resistivity should be used with care when applied to low-dimensional metals, for example the effective resistivity of small conductors is increased even in the absence of surface and grain-boundary scattering. The related concept of electron 'mean free path' needs also to be revisited. These questions could have significant implications in terms of the selection of most appropriate material systems for tera-scale metallization schemes. (paper)