Structure and Morphology of Microprotrusions Grown on Ar-Sputtered InP

The adsorption/desorption kinetics of TiCl₄on polycrystalline TiSi₂have been measured quantitatively by temperature-programmed desorption in order to better understand the chemical vapor deposition of the silicide from TiCl₄and SiH₄. For small exposures, only SiCl₂desorbs near 1150 K. The kinetics are second order with respect to surface chlorine, and the desorption activation energy E_dis 85±4 kcal/mol. As this state approaches saturation, SiCl₂desorbs from a second state near 700 K. The kinetics are also second order, but desorption occurs through a continuum of energetic pathways peaking at 57 kcal/mol. As this state saturates, a third desorption peak consisting of SiCl₄appears near 500 K. The kinetics are first order with respect to surface chlorine and also comprise a distribution of energetic pathways, which peak at 33 kcal/mol. Coadsorption studies with SiH₄were also performed. Surface chlorine appears to bond to Si, not Ti, on the surface. These kinetics are utilized to predictively model the chemical vapor deposition of TiSi₂thin films.