DFT investigation of HfCl4 decomposition on hydroxylated SiO2: first stage of HfO2 atomic layer deposition

Density functional theory is used to address the initial stage of HfO2 growth on hydroxylated SiO2 as a part of atomic layer deposition process of HfO2 on Si(1 0 0). We perform a constrained minimization procedure to investigate the reaction pathway of the HfCl4 molecular precursor decomposition on ultra-thin SiO2. This is done through the static excitation of one single normal vibrational mode of the precursor molecule. We find a chemisorbed state with an associated 0.48 eV adsorption energy. Starting from this minimum, and using the above pathway, an activation barrier of 0.88 eV is determined to arrive at a complex intermediate. Then the reaction end product is determined giving rise to a HCl adsorbed molecule on the surface.