Ultraviolet-induced chemical vapor deposition of silica films studied by surface-sensitive multiple-internal-reflection spectroscopy

Surface-sensitive multiple-internal-reflection-absorption infrared spectroscopy has been applied to the study of SiO2 photodepostion under far-ultraviolet illumination. A Si-H absorption line at 2208 cm-1 is shown to characterize the surface incorporation site of silicon atoms. Evidence is given for its assignment to O2SiH2 molecular configurations. A previously overlooked silicon incorporation path involving surface photoexcitation of water sites and reaction with silane molecules is identified, and shown to account for about 5% of silicon atom incorporation. Infrared spectroscopic data provide evidence for kinetic roughening of the deposition front, and the measure of the β exponent gives a value of 0.28±0.05, in fair agreement with theoretical and numerical predictions for ballistic and random deposition models.