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

Abstract

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\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$-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\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ at 973 K and 1.6\ifmmode\times\else\texttimes\fi{}${10}^{16}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ at 1123 K, (2) the concentration of self-interstitials, 3.5\ifmmode\times\else\texttimes\fi{}${10}^{10}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ at 1123 K, and (3) the activation energy of the silicon self-interstitial diffusion coefficient, 5.01 eV.