Interfacial effects on leakage currents in Cu/α-cristobalite/Cu junctions.

As the miniaturization trend of integrated circuit continues, the leakage currents flow through the dielectric films insulating the interconnects become a critical issue. However, quantum transport through the mainstream on-chip interfaces between interconnects and dielectrics has not been addressed from first principles yet. Here, using first-principles calculations based on density functional theory and nonequilibrium Green's function formalism, we investigate the interfacial-dependent leakage currents in the Cu/α-cristobalite/Cu junctions. Our results show that the oxygen-rich interfaces form the lowest-leakage-current junction under small bias voltages, followed by the silicon-rich and oxygen-poor ones. This feature is attributed to their transmission spectra, related to their density of states and charge distributions. However, the oxygen-poor interfacial junction may conversely have a better dielectric strength than others, as its transmission gap, from -2.8 to 3.5 eV, is more symmetry respect to the Fermi level than others.