  A modeling approach, based on an analytical solution of the semiclassical
multi-subband Boltzmann transport equation, is presented to study resistivity
scaling in metallic thin films and nanowires due to grain boundary and surface
roughness scattering. While taking into account the detailed statistical
properties of grains, roughness and barrier material as well as the metallic
band structure and quantum mechanical aspects of scattering and confinement,
the model does not rely on phenomenological fitting parameters.
