Photochemical vapor deposition of amorphous silica films using disilane and perfluorosilanes: Defect structures and deposition mechanism

Amorphous silicon dioxide films were deposited from oxygen, disilane (Si₂H₆), and perfluorosilanes (Si₂F₆ or SiF₄) by photochemical vapor deposition using a deuterium lamp at a substrate temperature of as low as 200 °C. It was found that by mixing Si₂F₆, defects such as H and OH in the films were effectively removed with an enhancement in the growth rate and a slight doping of fluorine into the films, while SiF₄ had no effect except a little doping of fluorine. The generation and extinction of defects including H, OH, and SiSi were investigated quantitatively by measuring infrared spectra and vacuum ultraviolet absorptions at the optical band edge. The model on the deposition process was proposed that photodissociated F-containing radicals eliminate H and activate the growing surface, resulting in enhancing the deposition rate.