Characterization of Thin Films Deposited from Benzene Using Microwave Plasma Polymerization

Abstract

Microwave plasma enhanced chemical vapor deposition (MWPECVD) is a cheap and easy method for the modification of materials surfaces to enhance some required property. In this study, benzene as a monomer was deposited on both Aluminum alloy (2024-T3) and glass slide substrates at several pressures and deposition times using MWPECVD. The chemical structure and surface properties of as-grown thin films were analyzed on glass using FTIR and NMR. It is found that benzene rings are not fully preserved in the film structure. Some benzene rings were converted to saturated alcohol and/or ester functional groups in the crosslinked film structure. The corrosion resistance of aluminum alloy substrates both bare and covered with plasma polymerized thin films was carried out by potentiodynamic polarization measurements in standard 3.5% NaCl solution at room temperature. The benzene deposited film was found to be not fully suitable for protection of aluminum substrate against corrosion. The only film that stayed intact post the corrosion measurement is that for the deposition condition of 30 mtorr for 90 minutes. The change in the processing parameters seemed to have a strong influence on the film protective ability. SEM was used to study the surface morphology of deposited films on aluminum. It is found that the polymerized film roughness decreases with increasing monomer pressure and deposition time. Adhesion test done on films deposited on glass showed that the best adhesion occurs for deposition condition of 30 mtorr for 90 minutes and poor adhesion occurred at 7 and 9 mtorr for 90 minutes.