Reliability and resistance projections for rhodium and iridium interconnects from first-principles

Abstract

We apply first-principles simulations to evaluate several properties related to the resistance and reliability of rhodium and iridium interconnects. We find that both Rh and Ir have significantly higher activation energies of diffusion than state-of-the-art Cu interconnects, suggesting greatly improved resistance to electromigration failure. Since the practical integration of metal interconnects requires an adhesion liner, we calculate the metal-to-metal adhesion, surface scattering characteristics, and via resistance of four potential liner materials: TiN, TiO, TaN, and TaO. We find that TiO gives the strong metal-to-metal adhesion for both Rh and Ir, minimizing the risk of delamination. None of the four liner materials considered are found to have a significant impact on surface scattering of Rh or Ir, while the N-containing liners give lower via resistance than the O-containing liners. This work helps build a better understanding of fundamental material properties related to the practical integration of potential next-generation interconnect metals used for advanced semiconductor technology.