High-speed deposition of dense, dendritic and porous SiO2 films by Nd: YAG laser chemical vapor deposition

Dense, dendritic and porous SiO2 films were prepared by laser chemical vapor deposition (LCVD) using a high-power continuous-wave mode Nd: YAG laser (206 W) and a TEOS (tetraethyl orthosilicate) precursor. The effects of laser power (PL) and total chamber pressure (Ptot) on the microstructure and deposition rate (Rdep) were investigated. Amorphous SiO2 films were obtained independent of PL and Ptot. Flame formation was observed between the nozzle and the substrate at PL > 160 W and Ptot > 15 kPa. At PL = 206 W, dense, dendritic and porous SiO2 films were obtained at Ptot < 20 kPa, Ptot = 23 kPa and Ptot > 25 kPa, respectively. The Rdep increased thousands of times under flame formation conditions, the highest Rdep being reached at 1200 μm h−1, 22,000 μm h−1 and 28,000 μm h−1 for the dense, dendritic and porous SiO2 films, respectively.