Dominant role of grain boundary scattering in the resistivity of nanometric Cu films

The dominant role of grain boundary scattering in the low-temperature resistivity of both SiO₂ and Ta/SiO₂ encapsulated Cu thin films is demonstrated by the experimental variation and quantification of film thickness, roughness, and grain size. The independent variation in film thickness (28--158 nm) and grain size (35--466 nm) is achieved through subambient temperature film deposition followed by annealing. Experimentally measured film resistivities are compared with both surface scattering and grain boundary scattering models for the classical size effect, showing the dominance of the latter.