Kinetic energy dependence of TiSi2 film growth from low energy Ti+ ion beams

The growth of TiSi2 thin films by using low energy (10-500 eV) Ti+ ion beam s on Si(1 1 1) has been studied by In situ Anger electron spectroscopy (AES ) and reflection high energy electron diffraction (RHEED) as well as ex sit u depth profile X-ray photoelectron spectroscopy (d-XPS). Stoichiometric Ti Si2 films were grown with Ti+ energies of 50 eV at a temperature of 600 deg rees C. The in situ RHEED and AES data reveal the existence of some element al Si in the surface region, whose concentration is dependent on the kineti c energy of the incoming Ti+ ions. Resolution of the chemical shift between the Si(2p) lines of the silicide and elemental silicon allows the ex situ d-XPS profiles to reveal the him composition and thickness. The effect of e nergetic ions in silicide film formation is discussed accordingly. The data show consistent trends that demonstrate that irradiation with Ti+ ions sup presses the diffusion of Si as the ion kinetic energy increases. It is prop osed that this radiation inhibited diffusion process is due to void formati on resulting from the high density of defects in the subsurface region whic h inhibits diffusion of Si atoms through the silicide film to react with in coming Ti atoms. (C) 1999 Elsevier Science B.V. All rights reserved.