NOVELTY - The multi-layer structure comprises a substrate (2), and N stackings, where N is greater than or equal to 1 and each stacking comprises a first coating (A) of silicon dioxide and a second coating (B) placed between the substrate and the first coating. A thickness of the second coating is less than or equal to 60 Nm, and the thickness of the second coating is two times higher than the thickness of the first coating, where the sum of thicknesses of the first coating and second coating is 100-500 Nm. The stacking has a refraction index of higher than 1.5.    USE - The multi-layer structure is useful for food packing and photovoltaic applications.    ADVANTAGE - The multi-layer structure can be economically manufactured with improved gas sealing property.    DETAILED DESCRIPTION - The multi-layer structure comprises a substrate (2), and N stackings, where N is greater than or equal to 1 and each stacking comprises a first coating (A) of silicon dioxide and a second coating (B) placed between the substrate and the first coating. A thickness of the second coating is less than or equal to 60 Nm, and the thickness of the second coating is two times higher than the thickness of the first coating, where the sum of thicknesses of the first coating and second coating is 100-500 Nm. The stacking has a refraction index of higher than 1.5. The second coating is made of silicon oxynitride (SiOxNyHz), where x is 0-2, y is 0-1 and z is less than (x+y)/10. The value of x decreases with an interface between the first coating and the second coating towards the substrate, and the value of y increases with an interface between the first coating and the second coating towards the substrate. The material of the first coating has a Young modulus of greater than or equal to 30 GPa, and the material of second coating has a Young modulus of less than or equal to 20 GPa. The stackings are obtained by conversion of perhydropolysilazane type inorganic precursor, and have a transmittance of higher than 90% corresponding to the silicon-hydrogen (Si-H) bond of the transmittance of the Si-H bond of the perhydropolysilazane type inorganic precursor before conversion measured by an infra-red spectrometry in reflection in the case of a polymeric material substrate and have an absorptance of less than 10% corresponding to the Si-H bond of the absorptance of the Si-H bond of the perhydropolysilazane type inorganic precursor before conversion measured by the infra-red spectrometry in transmission in the case of a silicon substrate. The first coating and second coating are made of amorphous materials, and the substrate is made of polymeric material. The structure further comprises n-1 coatings made of polymeric materials, where each coating is placed between two stackings. An INDEPENDENT CLAIM is included for a method of producing a multi-layer structure.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a multi-layer structure.    Substrate (2)    First coating (A)    Second coating. (B)