Insight into the Reaction Scheme of SiO2 Film Deposition at Atmospheric Pressure

Characterisation of an atmospheric pressure microplasma jet in combination with simulations have been used to determine reaction mechanism of SiO2-like film formation and reaction rate constants for several gas phase reactions in the He/hexamethyldisiloxane (HMDSO)(/O-2) plasma chemistry. Using a variable-length quartz tube, the gas residence time in the plasma effluent could be well controlled without changing plasma properties. A possible reaction scheme has been developed. Deposition rates, deposited profiles, carbon content of the films and the depletion of HMDSO could be reproduced by the simulation. The simulation indicates that HMDSO in He(/O-2) plasma dissociates preferentially into (CH3)(3)SiO and Si(CH3)(3), where the former radical serves as a main growth precursor.