Ultrathin carbon–fluorine film processing

Abstract: In conventional plasma polymerization processes, the bulk properties of the treated substrates are maintained whereas the surface properties are changed to the ones of the coating polymer. In contrast, materials with ultrathin non-closed layers and domains of plasma deposited compounds can show combined properties (from the surface of the bulk material and the non-closed layer) or even completely new behavior. This can be seen by analyzing e.g. the wettability (contact angle), the tribological properties, chemical functionalities or biological interactions. Ultrathin closed and non-closed films (domains) of fluorocarbon polymer were produced by means of RF-CVD (radio frequency aided chemical vapor deposition, plasma polymerization) with CHF3 as monomer gas; argon was added as additional process gas. Our work has been carried out in a symmetric capacitively coupled reactor at 13.56 MHz in the low-pressure, glow-discharge regime. The influence of pulsing the plasma by varying on- and off-times on the surface properties were investigated on silicon wafers as substrates. The obtained functionalized surfaces were characterized by means of advancing and receding contact angle measurements, X-ray photoelectron spectroscopy (XPS) as well as atomic force microscopy (AFM). [Copyright &y& Elsevier]