Overcoming Quantum Resistivity Scaling in Nanoscale Interconnects Using Delafossite PdCoO2

TL;DR

This paper demonstrates that layered PdCoO2 can outperform copper in nanoscale interconnects by maintaining low resistivity under quantum confinement, thanks to its anisotropic transport properties and suppressed boundary scattering.

Contribution

It introduces a quantitative framework linking electronic properties to resistivity scaling, showing PdCoO2's potential as a scalable interconnect material beyond copper.

Findings

PdCoO2 maintains near bulk conductivity at sub 30 nm scales.

Anisotropic mean free paths in PdCoO2 delay resistivity increase.

PdCoO2 outperforms copper in quantum confined regimes.

Abstract

Continued scaling into the sub 7 nm regime exacerbates quantum limited resistivity in Cu interconnects. We evaluated layered PdCoO2 and explicitly benchmarked it against Cu to identify mechanisms that maintain conductivity under confinement. Using a momentum resolved relaxation time formalism derived from the conductivity tensor, we link k and energy resolved velocities, life times, and mean free paths (MFPs) to thickness dependent resistivity for films and wires. PdCoO2 exhibits quasi 2D transport with high inplane velocities and strongly anisotropic MFPs (15 nm inplane, 3 nm outofplane near EF), whereas Cu shows an isotropic 22 nm MFP. Under identical boundary conditions including a realistic 2 nm liner/diffusion barrier for Cu, PdCoO2 displays suppressed boundary scattering and a much slower resistivity increase from bulk down to sub 30 nm, preserving near bulk conductivity and remaining viable at 2 nm. Thickness trends reveal dual slope changes in PdCoO2 (35 nm and 7 nm) set by anisotropic MFPs, contrasting with the single characteristic scale of Cu (40 nm). The calculated bulk values and scaling curves track available measurements for both materials. These results establish PdCoO2 as a scalable interconnect that outperforms Cu under quantum confinement and provide a quantitative framework to screen layered conductors for next generation nanoelectronic interconnects.