Evidence of the filling of nano-porosity in SiO2-like layers by an initiated-CVD monomer

Although very promising results in terms of moisture and oxygen barrier properties have been achieved by alternating organic and inorganic layers composing a multilayer structure, the impact of the organic interlayer on the global barrier performance is still unraveled. Three main hypotheses have been reported in literature so far, although consistently applied to the case of a liquid-phase polymerization process of the organic layer: smoothening of the polymeric substrate surface by the organic layer; decoupling, by means of a tortuous path, of the defects present in two adjacent inorganic barrier layers; filling of the nano-defects present in the barrier layer during the (liquid phase) polymerization of the organic layer. Within this framework, this contribution reports on the adsorption/desorption study of an initiated-CVD (i-CVD) monomer (trimethyl-trivinyl-cyclotrisiloxane), V3D3, performed on plasma deposited SiO2-like layers by means of in situ spectroscopic ellipsometry measurements. The SiO2-like layers are used as moisture permeation barriers followed by an organic interlayer deposited by means of the i-CVD technique. The experimental evidence for the V3D3 molecule infiltration and filling in the open micro/meso porosity present in the inorganic layer underneath, confirms the hypothesis on the filling of nano-defects in the barrier layer upon organic layer deposition and shows that the defect filling occurs also in the case of a CVD-based approach.

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► We performed i-CVD monomer ads./des. studies by in situ SE on SiO2 barrier layers.
► The filling by i-CVD monomer in the open micro/meso pores of SiO2 layers is shown.
► The barrier layer nanodefects filling by the organic layer hypothesis is confirmed.
► This hypothesis is proved also for CVD-based process.