Suppression of Size Effect in MoPd Thin Films for Nanoscale Interconnects

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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.72</inf>Pd<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">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 N₂ atmosphere. The grain size of the 30 nm-thick Mo<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.72</inf>Pd<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">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 MoO2 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.