Analysis of surface roughness scattering and its contribution to conductivity degradation in nanoscale interconnects

Abstract

We use a quantum mechanical calculation of momentum loss rates as function of spatial frequency of surface roughness to identify which frequencies contribute most strongly to conductivity degradation. We combine these calculations with surface roughness spectrum from atomic step model matched to AFM data. We find that roughness with period on the order of 300 nm gives greatest contribution to resistance increase, but that scattering from typical Cu surfaces can be expected to be nearly specular. We attribute apparent surface scattering to adhesion/barrier layer properties rather than interface or surface roughness.