Magnetron sputtered a-SiOxNy thin films: A closed porous nanostructure with controlled optical and mechanical properties

Amorphous silicon oxynitride coatings with similar composition and different closed porosity were prepared by magnetron sputtering. Pores size, shape and distribution were evaluated by scanning electron microscopy and transmission electron microscopy. Raman and EELS analysis proved that the pores are filled with molecular nitrogen trapped during deposition.The mechanical properties evaluated by nanoindentation shows that the presence of closed nano-porosity does not compromise the mechanical integrity of these coatings. The introduction of closed porosity is shown as a good strategy for obtaining lower dielectric constant silicon oxynitride coatings with similar composition while keeping the good mechanical properties (∼13 GPa) characteristic of this type of coatings. The presence of close porosity gives also a good stability of coatings properties as compared to open porosity microstructures where gas phase in contact with the coatings can affect coatings properties.

Amorphous silicon oxynitride coatings with similar composition and different closed porosity were prepared by magnetron sputtering. EELS analysis revealed that molecular nitrogen is trapped inside the pores during deposition. The introduction of closed porosity is shown as a good strategy for obtaining low dielectric constant silicon oxynitride coatings with similar composition, keeping the good mechanical properties characteristic of this type of coatings.Figure optionsDownload as PowerPoint slideHighlights
► SiOxNy coatings with closed porosity were deposited by magnetron sputtering.
► Closed porosity achieved for the first time by controlling the geometry of deposition.
► The closed nano-porosity does not compromise the mechanical integrity of the coatings.
► Closed porosity is a good strategy for SiOxNy coatings with similar composition and different dielectric constant.
► Close pores avoid the drawbacks of water and other impurities diffusion.