Precursor-dependent structural and electrical characteristics of atomic layer deposited films: Case study on titanium oxide

Thin (10–20 nm) TiO2 films were atomic layer deposited from TiCl4, Ti(OC2H5)4, H2O and H2O2 in the substrate temperature range 125–350 °C. The structure, chemical composition and electrical properties were correlated to the process temperature and nature of precursors, whereas the effect of precursors on conduction mechanisms was considerable only in the films grown at 125 °C, otherwise controlled by oxide-electrode interfaces. The use of chloride resulted in films with highest permittivity while the use of hydrogen peroxide resulted in lowest permittivity but also in lowest leakage. The post-deposition (pre-metallization) annealing resulted in densification and (re)crystallization of TiO2 layer but also in thickening of low-permittivity interface layers.