Functionalization of self-organized networked SiOxHyCz nano-islands deposited by atmospheric pressure microwave plasma torch on Au/Si(100) substrates patterned by nano-indentation

X. Landreau, B. Boëns, B. Lanfant, T. Merle, G. Bouscarrat, C. Dublanche-Tixier, R. Zerrouki, P. Tristant
Université de Limoges, FR

Keywords: SiOxHyCz film, PECVD, nano-islands, FTIR, nano-indentation


A coaxial injection microwave excited plasma torch operating at atmospheric pressure is applied to synthesizing SiOxHyCz nano-islands from hexamethyldisiloxane precursor on prepatterned Au/Si(100) substrates.Prior to the PECVD deposition, the substrates are patterned by nano-indentation. SEM characterizations demonstrate that nano-indents act as trapping sites, allowing ripening of SiOxHyCz nano-dots at those locations. The results show that island ordering is intrinsically linked to the nucleation and growth at indented sites and strongly depends on pattern parameters (interspacing, deep, diameter). In a second step, a thorough Fourier Transformed Infra-Red (FTIR) spectroscopy study is performed on SiOxHyCz nano-hillocks with the aim to directly correlate the Si-O-Si vibrators conformation with the surface growth mechanisms and with the morphological and chemical islands properties. Results demonstrate that the TO3 vibrational mode (revealing acute Si-O-Si angles) is predominant, reflecting the sharp and pointed nature of the domed-like surface. Concomitantly, strong correlations are established between the islands compactness and the TO2 mode variations (obtuse Si-O-Si angles) as well as with the downward diffusion amplitude of the deposited chemical species. Finally, we report on the selective alkyno-functionalization of the nano-islands surface, followed by the addition of coumarin fluorophore through microwave-assisted click-chemistry process for a sensing purpose.