Argon plasma immersion ion implantation of polystyrene films

Plasma immersion ion implantation (PIII), using bias voltages of 5, 10, 15 and 20 kV in an argon plasma and fluences in the range of 2 × 1014–2 × 1016 ions/cm2, was applied to 100 nm polystyrene films coated on silicon wafer substrates. The etching kinetics and structural changes induced in the polystyrene films were investigated with ellipsometry, Raman and FTIR spectroscopies, optical and scanning electron microscopies, atomic force microscopy and contact angle measurements. Effects such as carbonisation, oxidation and cross-linking were observed and their dependence on the applied bias voltage is reported. Variations in the etching rate during the PIII process and its relationship to carbonisation of the modified surface layer are explored.