In-diffusion of Pt in Si from the PtSi/Si interface

The in-diffusion of platinum in n-type silicon from a platinum silicide source was investigated using mainly deep-level transient spectroscopy and C-V measurements. MeV helium backscattering, electron Auger spectroscopy, x-ray diffraction, and scanning electron microscopy observations were also used to obtain a metallurgical characterization of the samples. The Si samples were Pt diffused in a 2×{}10^-7-Torr vacuum furnace. The profiles of the platinum in silicon measured between 973 and 1123 K and for times ranging from a few tens of minutes to several days show a behavior that cannot be described with a complementary error function characteristic of dissociative diffusion via vacancies. The results can be interpreted by using the mechanism of kick-out diffusion via self-interstitials into a dislocation-free semi-infinite solid. From the model it was possible to estimate (1) the solid solubility of the electrically active platinum, 1.95×{}10¹⁴ cm^-3 at 973 K and 1.6×{}10¹⁶ cm^-3 at 1123 K, (2) the concentration of self-interstitials, 3.5×{}10¹⁰ cm^-3 at 1123 K, and (3) the activation energy of the silicon self-interstitial diffusion coefficient, 5.01 eV.