We clarified the correlations between resistivity and microstructures in the depth direction of copper (Cu) wires. The resistivity of Cu wires increased with the polishing depth Delta H, and the influence of Delta H on resistivity increment was significant for 60 nm wide Cu wires. We attributed this to the fact that the deeper the depth and the finer the line width, the smaller are the grain sizes and the lower are the fractions of {111} textures and Sigma 3 coincident site lattice boundaries. Among the above factors, the grain size was the dominant factor determining the resistivity of less than 100 nm wide Cu wire. (C) 2009 Elsevier B.V. All rights reserved.