The reaction between a thin film (126 nm) of Co and Si has been studied at 450 C for 24 h under high
vacuum conditions, in the presence of a FeZr barrier layer. Without a diffusion barrier layer between
Co and Si, Co2Si forms at 350 C as the initial phase while CoSi2 forms at 550 C. The FeZr barrier layer
changed the flux of atoms arriving at the reaction interface. Co reacted with the Si from the substrate
and formed a mixed layer of CoSi and CoSi2 in the interlayer region. The use of the FeZr diffusion barrier
has been demonstrated to lower the temperature formation of CoSi2 to 450 C. The reactions were characterised
by Rutherford backscattering spectrometry, Auger electron spectroscopy depth profiling, X-ray
diffraction using CoKa radiation and scanning electron microscopy.