Electrical resistivity of sputtered Cu/Cr multilayered thin films

Parallel (in-plane) electrical resistivities of single-layered Cu and Cr fi lms, and Cu/Cr multilayered thin films sputter deposited on Si substrates w ere evaluated as a function of layer thicknesses ranging from 2.5 to 150 nm in the temperature range of 4-325 K. The resistivity of the multilayers at a given temperature increased and residual resistivity ratio decreased wit h decreasing layer thicknesses. At 300 K, the resistivity of a 1 mu m thick Cu film was approximately equal to the bulk value, but the resistivity of the Cr film was an order of magnitude higher than that of bulk Cr. The micr ostructures of the multilayers and the single-layered Cu and Cr thin films were characterized by transmission electron microscopy. For layer thickness es ranging from 2.5 to 150 nm, the multilayers exhibited sharp, planar inte rfaces between the two phases. The individual Cu and Cr layers were nanocry stalline with near-equiaxed grains in Cu and columnar grains in Cr. The dep endence of electrical resistivity on the layer thickness of multilayers is explained using a model that accounts for interface scattering and thin-fil m resistivities of polycrystalline Cu and Cr. (C) 1999 American Institute o f Physics. [S0021-8979(99)06201-5].