Low temperature deposition of inorganic thin films by ultraviolet laser-assisted chemical vapor deposition

Inorganic silicon nitride film is deposited by argon fluoride (ArF) excimer laser photolysis of ammonia/silane mixtures at low substrate temperature of 100 C on silicon substrate. Laser beam was illuminated in parallel to the substrate surface to avoid sample damage or heating. In order to achieve high deposition rate, the laser pulse energy was shown to be a dominant factor, and low substrate temperature condition required elevated laser energy density to achieve sufficient deposition rate. Laser pulsing frequency also improved the deposition rate yet at lowered deposition rate per laser pulse as the responsible reactant gas decomposition mechanisms were explored by in-situ emission spectroscopic analysis. Upper limit of deposition rate was formed by nanoparticles formation, and the deposition rate of 87 nm/min has been demonstrated. However, it is shown that when film deposition is too fast or film thickness is insufficient, rapid oxidation occurs upon exposure to ambient environment. Further parametric tuning and characterizations of resulting deposition materials are under way. Delivery of reactant gases and reaction kinetics also need to be optimized considering a unique reaction zone involved with the laser-assisted chemical vapor deposition configuration.