Nano-Ridge Bending during Conformal Ruthenium Metallization: Implications for Interconnect Fabrication

Conformal deposition of ruthenium in a damascene-like approach has shown promising results to form Ru nanowires with superior resistive and reliability characteristics for application as interconnects in very large-scale integrated circuits. Nevertheless, the mechanical integrity of nanostructures during process development for novel materials’ integration is paramount. In this paper, a mechanism of dielectric pattern distortion is identified, which occurs during conformal deposition of ruthenium and cannot be explained by metal film stress alone. Using experimental characterization and thermodynamic analysis, we show that metal-coated dielectric nanoridges bend under the influence of zipping stresses and establish contact to minimize their free energy.