Step coverage of thin titania films on patterned silicon substrate by pulsed-pressure MOCVD

Thin titania (TiO₂) films were deposited on patterned silicon (Si), and silicon nitride (SiN) substrates by pulsed-pressure metal organic chemical vapor deposition (PP-MOCVD) using titanium tetra-isopropoxide (TTIP) as a precursor. The deposition temperature was varied between 400 °C and 600 °C under peak pressure of up to 370 Pa. The surface morphology and thicknesses of the films were examined using a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to analyze the phases of TiO₂. The thicknesses of TiO₂ films were in the range of 200-350 nm. The phase of thin TiO₂ at the deposition temperatures was anatase, exhibiting slight reduction in grain size with increasing temperature. The composition of the films was qualitatively identified by energy dispersive X-ray spectroscopy (EDS). The principal composition of the thin films was TiO₂. The conformality of TiO₂ films on features was evaluated based on statistical analysis. The step coverage of TiO₂ at low temperatures showed a good even coating with a growth rate of more than 20 nm/min. As the temperature increased, the evenness of the coating along a micron-scale step decreased.