Ag-Cu amorphous alloy thin-films with unusually high electrical conductivity

Copper is the state-of-the-art interconnect material in integrated circuits and other electronic applications. At the deeply scaled-down dimensions of a few nanometers, the resistivity of polycrystalline copper and other metals increases sharply due to enhanced electron scattering at grain boundaries and interfaces. Here, we report that fully amorphous thin-films of binary Ag-Cu alloy could potentially overcome the above limitations imposed by interfaces. The resistivity of 10 nm thick Ag-Cu amorphous film is ∼ 2.97 μOhm-cm, pure Ag film is ∼ 1.59 μOhm-cm, and pure Cu film is ∼ 20.5 μOhm-cm of similar thickness. The valence band structure of the amorphous film reveals that d-band interaction between Ag and Cu atoms broadens the electronic density of states resulting in high electrical conductivity. Our approach offers a new strategy for the potential use of amorphous metals as interconnects in advanced technology nodes and deeply-scaled electronics.