Finite Size Effects in Highly Scaled Ruthenium Interconnects

TL;DR

This paper develops a predictive model for resistivity in scaled ruthenium interconnects, highlighting the dominant role of grain boundary scattering and achieving predictions within 10% accuracy.

Contribution

It introduces a methodology combining the Mayadas-Shatzkes model for thin films with a modified model for nanowires to predict resistivity in Ru interconnects.

Findings

Resistivity increases as Ru film thickness decreases.

Grain boundary scattering dominates in scaled Ru interconnects.

Model predictions align within 10% of experimental data.

Abstract

Ru has been considered a candidate to replace Cu-based interconnects in VLSI circuits. Here, a methodology is proposed to predict the resistivity of (Ru) interconnects. First, the dependence of the Ru thin film resistivity on the film thickness is modeled by the semiclassical Mayadas-Shatzkes (MS) approach. The fitting parameters thus obtained are then used as input in a modified MS model for nanowires to calculate wire resistivities. Predicted experimental resistivities agreed within about 10%. The results further indicate that grain boundary scattering was the dominant scattering mechanism in scaled Ru interconnects.