Suppression of Size Effect in MoPd Thin Films for Nanoscale Interconnects

Abstract

As the downscaling of interconnects continues, overcoming the size effect, which significantly increases resistivity in ultrathin films, has become a critical challenge. In this study, Mo-Pd alloy thin films with varying Pd compositions were investigated to improve electrical performance by controlling grain growth and suppressing electron scattering. Particularly, the Mo<inf>0.72</inf>Pd<inf>0.28</inf> composition demonstrated superior performance, achieving a resistivity of 76 μΩ•cm at 4 nm thickness after annealing at 700°C for 1 min in an N atmosphere. The grain size of the 30 nm-thick Mo<inf>0.72</inf>Pd<inf>0.28</inf> film increased from approximately 3 nm in the as-deposited state to 10 nm after annealing, leading to enhanced crystallinity and reduced grain boundary scattering. XRD analysis confirmed the stabilization of Pd phases in high-Pd-content films, while Mo-rich films showed MoO<inf>2</inf> formation after annealing, suggesting composition-dependent oxidation behavior. These results demonstrate that optimizing Pd content and thermal treatment effectively mitigate the size effect and improve electrical properties, making Mo-Pd alloys promising candidates for next-generation interconnects.