Grafting of perfluorinated organic film on the Si surface in aqueous solution

Abstract

In the past few years, organic film prepared on the silicon (Si) surface has become attractive owing to the wide range of potential application, low cost and good performance. In this paper, perfluorinated organic film was prepared on the Si surface in aqueous solution using one-step dipping method. On the Si surface, 4-nitrobenzene diazonium (NBD) tetrafluoroborate was firstly reduced with the presence of hydrofluoric acid in the aqueous media. The aryl radicals can then directly graft onto the Si substrate surface. In the meantime, the 2-(Perfluorooctyl)ethyl methacrylate can be initiated by aryl radicals and chains formed by the perfluorinated organic monomer in the aqueous solution can grafted onto Si surface. After grafting, the substrate surfaces and cross-section were characterized by SEM (FEI SIRION 200) and AFM which was uses a Digital Instrument Nanoscope IIIa operated in tapping mode in the air. The result showed that perfluorinated organic film was successfully grafted on the Si surface. Furthermore, the polymer film was composed of polyvinyl and polynitrophenylene which was comprised in the polyvinyl chain throughout the entire grafting process. Under this circumstance, the polymer film had uniform chemical composition from inner layer to external layer. In the experiment, we find that the monomer and NBD was grafted on the surface and the properties of the organic film are suitable for through-silicon-via(TSV) which is of good application potential.