Ultralow Electron-Surface Scattering in Nanoscale Metals Leveraging Fermi Surface Anisotropy

TL;DR

This paper demonstrates that metals with anisotropic Fermi surfaces can significantly reduce surface scattering and resistivity in nanoscale wires, identifying promising materials like CoSn and YCo3B2 for interconnects.

Contribution

It introduces a new descriptor for resistivity scaling in anisotropic conductors and screens thousands of metals to find optimal materials for nanoscale interconnects.

Findings

Anisotropic Fermi velocities suppress surface scattering in nanoscale metals.

Certain intermetallics and borides outperform copper at 5 nm wire dimensions.

Proposed materials exhibit 2-3x lower resistivity than copper.

Abstract

Increasing resistivity of metal wires with reducing nanoscale dimensions is a major performance bottleneck of semiconductor computing technologies. We show that metals with suitably anisotropic Fermi velocity distributions can strongly suppress electron scattering by surfaces and outperform isotropic conductors such as copper in nanoscale wires. We derive a corresponding descriptor for the resistivity scaling of anisotropic conductors, screen thousands of metals using first-principles calculations of this descriptor and identify the most promising materials for nanoscale interconnects. Previously-proposed layered conductors such as MAX phases and delafossites show promise in thin films, but not in narrow wires due to increased scattering from side walls. We find that certain intermetallics (notably CoSn) and borides (such as YCo$_3$B$_2$) with one-dimensionally anisotropic Fermi velocities are most promising for narrow wires. Combined with first-principles electron-phonon scattering predictions, we show that the proposed materials exhibit 2-3x lower resistivity than copper at 5 nm wire dimensions.