A theoretical study on the surface reaction of tetrakis(dimethylamino)titanium on titanium oxide.

ABSTRACT

Tetrakis(dimethylamino)-titanium (TDMAT, Ti(NMe2)4) has been used for the low-temperature atomic layer deposition (ALD) process of titanium oxide (TiO2) films. In this study, the chemisorption of TDMAT on a titanium oxide surface using a slab model was simulated by density functional theory (DFT) calculation. We calculated the activation energy for the chemisorption and predicted the final chemisorbed species. A TiO2 slab model was constructed with the optimized number of -OH surface groups. Three serial ligand exchange reactions between a TDMAT molecule and the TiO2 slab were exothermic with low activation energies of 0.16-0.46 eV, which can explain the low processing temperatures of the ALD TiO2 processes. Our DFT calculation showed that three NMe2 ligands of TDMAT would be released and the surface species of -TiNMe2 would be formed, which is in good agreement with the experimental observation in the literature.