Point defects in Si after formation of a TiSi2 film: Evidence for vacancy supersaturation and interstitial depletion

The influence of TiSi2 formation on native Si point defects has been studied at temperatures between 800 and 890 degrees C. Sb and B in doping superlattices were employed to trace point defect behavior. Formation of TiSi2 at 890 OC gives rise to an interface root-mean-square (rms) roughness of 22 nm. Ambiguities in the interpretation of the data arising from possible secondary ion mass spectroscopy artifacts due to sputtering through such a rough interface were avoided by etching the TiSi2 film and replanarizing the Si surface. A rms roughness of 0.05 nm was obtained, as checked by atomic force microscopy and cross-sectional transmission electron microscopy. We observed an enhancement in Sb diffusion and retardation of B diffusion over control samples without TiSi2. This indicates a vacancy supersaturation and an interstitial depletion in the Si due to the presence of the silicide. Possible mechanisms of vacancy creation and interstitial depletion are discussed. (C) 1996 American Institute of Physics.