Mechanisms of the Resistivity Size Effect in Metallic Thin Films Computed Using Realistic Tight-Binding Models and the Kernel-Polynomial Method*

The resistivity size effect is an important limitation in device interconnect technology. Specifically, as the dimensions of interconnect wires approach ~10nm scales, increased resistivity becomes a fundamental limitation to device performance. While it has been understood that electron scattering from surfaces and grain-boundaries are responsible, dominant sources of scattering remain somewhat unclear. Computational approaches can play an important role in elucidating the resistivity size effect.

In this contribution, an approach based on realistic tight-binding models fit carefully to Density-Functional Theory (DFT) results is coupled with an efficient numerical approach based on the Kernel-Polynomial Method (KPM) is used to compute resistivity in Ruthenium thin films with the addition of steps and static phonon disorder. It is shown that single-crystalline films, which have been realized experimentally, can exhibit resistivity values comparable to bulk values, and that surface steps have a minimal impact on resistivity. The potential role of electron-phonon scattering at surfaces is also discussed.