Surface reactions as carbon removal mechanism in deposition of silicon dioxide films at atmospheric pressure

The deposition of thin SiOxCyHz or SiOxHy films by means of an atmospheric pressure microplasma jet with helium/hexamethyldisiloxane (HMDSO)/O-2 mixtures and the surface reactions involving oxygen have been studied. It is shown, that the carbon content in the film can be controlled by choosing the right O-2/HMDSO ratio in the gas mixture. The microplasma jet geometry and localization of the deposition at a spot of few square millimeters allows studying the role of oxygen in the deposition process. This is done by alternating application of He/HMDSO plasma and He/O-2 plasma to the same deposition area, here achieved by a treatment of a rotating substrate by two jets with above mentioned gas mixtures. It is shown that carbon-free SiOxHy film can be deposited in this way and that surface reaction with oxygen is the main loss mechanism of carbon from the film. (C) 2011 American Institute of Physics. [doi:10.1063/1.3565965]