Soft Plasma Polymerization of Gas State Precursors from an Atmospheric Pressure Corona Plasma Discharge

An atmospheric pressure nonthermal equilibrium corona plasma jet is described for depositing polymeric coatings with a high degree of functional chemistry retention. A long chain perfluorocarbon molecule was introduced as a vapor into a helium plasma at atmospheric pressure and coatings were deposited onto Si wafers at rates of 60−100 nm/min. XPS, FTIR and contact angle measurements indicate that a controlled polymerization reaction took place through the vinyl group of the monomer, with minimal fragmentation of the functional perfluoro chain. Electrical characterization of the corona plasma indicates that the power coupled into the jet was 6.8 W. It is proposed that low specific energy (J/cm 3 ) coupled into the plasma region is inherent to this plasma type and enables deposition of coatings with minimal fragmentation of the precursor monomer molecule. The system is inherently suitable for small-to-moderate area, high-added-value functional coating.