Cobalt silicide formation on a Si(100) substrate in the presence of an interfacial (Fe90Zr10) interlayer

The reaction between a thin film (126nm) of Co and Si has been studied at 450°C for 24h 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 CoKα radiation and scanning electron microscopy.