Substitutional gettering of platinum by diffusion into ion-beam damaged silicon

The diffusion of platinum into lightly damaged regions of n-type silicon has been investigated using deep-level transient spectroscopy and capacitance-voltage profiling applied to platinum-silicide Schottky diodes. The diodes had been implanted through the junction with ions of O,F, or Cl and subsequently annealed at a temperature of 700 degrees C. The distribution of in-diffused Pt was obtained by monitoring the electron emission from the acceptor level (E(C)-E(T) = 0.23 eV) of platinum occupying a distorted substitutional configuration. For a typical implantation dose( approximate to 10(11) cm(-2)) we recorded enhanced accumulation of Pt by about two orders of magnitude as compared to diffusion into non-implanted material and found that the in-diffused Pt was distributed approximately congruous with the vacancy distribution generated during implantation. This apparent decoration of the primary damage profile occurs without simultaneous introduction of other electrically active defects on a comparable scale. We infer that the residual damage present during annealing is sufficient to promote accumulation to saturation of substitutional Pt in the region of primary implantation damage. This rather remarkable property of guided in-diffusion, a kind of gettering phenomenon, may have potential applications in Si-device processing.