Kinetic Study of Tetrakis(Dimethylamido)Titanium and Titanium Tetrachloride Adsorption on a Silicon Surface in Atomic Layer Deposition: A DFT Calculation

Abstract

The adsorption characteristics were studied at room temperature (RT) of tetrakis(dimethylamido)titanium (TDMAT) and titanium chloride (TiCl4) on the Si(100)-2 × 1 surface in atomic layer deposition (ALD) of titanium dioxide (TiO2). Density functional theory (DFT) with the B3LYP/6-31G(d,p) level through Gaussian 09 was used to calculate the adsorption characteristic and the mechanism of surface reaction. The potential energy profile was evaluated to investigate the reaction mechanisms. All the states in the adsorption step were found below the reactant level, indicating that the TDMAT molecule is adsorbed on the silicon surface spontaneously at RT. The reaction mechanisms were started by breaking of O–H bond, followed by breaking the Ti–N and Ti–O bonds, respectively. To clarify the reaction mechanism in the adsorption step, the transition state was divided into two sub-stages, namely the O–H break (TS1) and the Ti–N break (TS2). In addition, the initial adsorption of TiCl4 on the hydroxylated silicon surface was calculated. The reaction mechanism and the energy profile of TDMAT and TiCl4 were discussed.