Open air deposition of SiO2 film from a cold plasma torch of tetramethoxysilane-H2-Ar system

A rf plasma beam was generated in the stream of atmospheric pressure argon to be exhausted from a cylindrical nozzle into air. The temperature measurements indicate a nonequilibrium low temperature nature of this plasma. By using this cold plasma torch, films were deposited on the substrates placed in air at growth rates higher than 100 Å/s by feeding tetramethoxysilane into the plasma. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy revealed that the films were essentially SiO2 and their structures and properties could be improved by admixing hydrogen in the plasma. The SiO2 films deposited at a rate of 120 Å/s from Si(OCH3)4-H2-Ar plasma had surfaces as smooth and hard as Corning 7059 glass.