Etching and structural changes of polystyrene films during plasma immersion ion implantation from argon plasma

Abstract Polystyrene films of 100 nm thickness were modified using plasma immersion ion implantation (PIII) with argon ions of energy 20 keV and fluences in the range 2 × 10 14 –2 × 10 16  ions cm −2 . The structure and properties of the films were determined by ellipsometry and FTIR spectroscopy, as well as AFM, wetting angle measurements, profilometry and optical microscopy. The effects of oxidation, carbonization, etching and gel-formation were observed. The etching rate was found to decrease with PIII fluence. The rates of degradation with increasing fluence of the aromatic and aliphatic parts of the polystyrene macromolecule were found to be similar. Oxidation of the polystyrene film ceases at fluences greater than 10 15  ions cm −2 . The surface morphology of the film did not change with PIII fluence. Washing with toluene produced surface wrinkling for low fluences up to 10 15  ions cm −2 while at high fluences the modified films were stable.