The epitaxial growth of (100) Cu on (100) Si reported recently using evaporation is analyzed to determine the epitaxial relation between Cu and Si, and also the crystalline quality of the Cu films. A 45° rotation between the (100) plane of Cu and that of Si around their (001) axis is shown to be needed for the lattice match. Such an epitaxial relation is confirmed by the grazing angle x‐ray diffraction, with the [010] of Cu parallel to the [011] of Si. The channeling analysis of a 2‐&mgr;m‐thick Cu film shows a 10% minimum near the surface.