Initiated-Chemical Vapor Deposition of Polymer Thin Films: Unexpected Two-Regime Growth

Abstract : Initiated‐chemical vapor deposition (iCVD) is a very promising technique which has demonstrated the ability to deposit a large variety of polymers that can be integrated in micro‐nanotechnology applications. However, studies on the underlying growth mechanisms responsible for the formation of these thin films remain scarce in the literature. This work shows that the iCVD growth follows surprisingly two regimes: in the first stage of the growth, the deposition rate is relatively slow then increases with the deposition time until a linear growth is reached. The presence of these two growth regimes can be interpreted by taking into account, as the iCVD growth progresses, that the synthesized polymer chains help the monomer adsorption on the substrate which locally increases the concentration of monomers available for the polymerization and thus the growth rate. This increase of the local concentration of monomer consistently correlates with the formation of polymer chains with higher molar mass.