Diffusion of ion-implanted As in TiSi2

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Abstract
Arsenic has been implanted into TiSi2 films to study its diffusivity during subsequent annealing between 600 and 800 °C in vacuum. The diffusion coefficient turns out to be so high that the As redistributes over the entire TiSi2 film (thickness 200 nm) at temperatures as low as 600 °C. In addition to this some of the As segregates at the TiSi2/polycrystalline Si interface and part of the implanted As remains immobile in the as‐implanted distribution. The mobile fraction is limited by the solubility of As in TiSi2 which has been determined from the As concentration in the bulk. This solubility turns out to be quite substantial and could be described by a Boltzmann relation with an activation energy of 1 eV and a preexponential factor of 1.06×1025 at/cm3. Evaporation of As occurs above 600 °C and can be prevented by oxidizing the TiSi2 film. The electrical resistivity and the stress of the silicide film indicate that implantation damage can only be eliminated by annealing at 800 °C, the sintering temperature of the silicide.