Fundamental studies on the decomposition mechanism of Ti(OC₃H₇)₄ and TiO₂ film evolution on Si(100) and Pt(100) surfaces

Abstract
Decomposition behaviors of titanium tetraisopropoxide (TTIP, Ti(OC₃H₇)₄) and TiO₂ film evolution mechanism on Si(100) and Pt(100) surfaces have been studied using thermal desorption technique. TTIP is dissociated on Si(100) below 350K so that the silicon surface is covered with iso-propoxy ligands and hydrogen originating from TTIP. The iso-propoxy ligands adsorbed on the silicon surface react with hydrogen to produce iso-propanol between 350K and 650K, and some of the ligands produce propylene and acetone at 500K~700K. Hydrogen exists as monohydride on the silicon surface showing a characteristic desorption peak at 780K. At higher dosages, 'ITIP is not completely dissociated and some of iso-propoxy ligands are still bound to titanium even at 700K. These intact ligands of TTIP produce acetone/iso-propanol or propylene at 800K~1000K by disproportionation among themselves or by the simple decomposition of C-O bond in the ligands. Surface decomposition reactions on Pt(100) surface are similar to those on silicon. However, temperatures at which the characteristic reactions occur are lower than those on silicon and the amounts of propylene desorption are smaller than those on Si(100) surface. Accordingly, TiO₂ film obtained on platinum is contaminated by carbon to smaller extents than one obtained on silicon.