In-situ x-ray diffraction and resistivity analysis of CoSi2 phase formation with and without a Ti interlayer at rapid thermal annealing rates
Abstract
The sequence of CoSi2 phase formation, with or without Ti interlayer, on polycrystalline silicon at rapid thermal annealing rate was analyzed in-situ by monitoring the x-ray diffraction (XRD) peak intensity and resistivity as functions of temperature. As expected, placing Ti interlayer (2 nm and 3.4 nm) between Co and polycrystalline. Si shifted the formation of CoSi2 to higher temperature and reduced the temperature range between the start of CoSi formation and CoSi2 formation. The onset formation temperatures for CoSi were found to be about 440, 575 and 600°C and the temperature of completion of CoSi2 formation to be about 640°C, 715°C and 715°C for pure Co, Co/2 nm Ti and Co/3.4 nm Ti, respectively. These results, proved the role of Ti interlayer as a diffusion barrier during the initial stages of the Co-Si reaction.