Si(100) and (111) oriented silicon wafers were used as a substrate for metallic bilayers deposition of copper and gold. Cu/Au/Si structures were obtained by thermal evaporation and then heated below 400°C in vacuum. These solid-state reactions occurred in the samples have been studied using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), scanning electronic microscopy (SEM) and X-ray dispersive energy analyzer (XDE). The study shows that heat treatment at 200°C of the multilayered Cu/Au/Si structure leads to the formation and the co-existence of both Cu 3 Si and Cu 4 Si copper rich-silicides with the expansion of their respective cells, independently of the orientation of the substrate. The increasing of the annealing temperature until 400°C leads to the growth of well-oriented crystallites corresponding to Cu 3 Si and Cu 4 Si silicides on Si(111) but only Cu 4 Si crystallites with square and rectangular shapes on Si(100). The thermal stability of formed copper silicides after heat treatment at 400°C during 30min for both Cu/Au/Si(100) and Cu/Au/Si(111) systems is analyzed.