Conformity of Silica-like Thin Films Deposited by Atmospheric Pressure Townsend Discharge and Transport Mechanisms

In this paper, homogeneous and dense silicon-based coatings have been deposited from hexamethyldisiloxane (HMDSO: $\hbox{Si}_{2}\hbox{O}(\hbox{CH}_{3})_{6}$) on patterned silicium in a Townsend dielectric barrier discharge operating at atmospheric pressure. A brief description of the physical mechanisms ruling the step coverage is first described, followed by a description of the atmospheric pressure plasma process used. The step coverage is discussed with regard to the aspect ratio of the patterned wafers. Coatings deposited in and after the discharge region have also been characterized to understand the influence of plasma activation. In order to understand the experimental results, numerical simulations have been performed using a simplified reactive transport model. These results provide information and first general insight on the physical mechanisms ruling the conformity of silicon-based films deposited with this technique.