Low refractive index SiOF thin films prepared by reactive magnetron sputtering

Abstract

We have studied low refractive index fluorine doped silica thin films prepared by reactive magnetron sputtering. Two experimental parameters were varied to increase the porosity of the films, the geometry of the deposition process (i.e., the use of glancing angle deposition) and the presence of chemical etching agents (fluorine species) at the plasma discharge during silica film growth. The microstructure, chemistry, optical properties, and porosity of the films have been characterized by scanning electron and atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-Vis, and spectroscopic ellipsometry. It is found that either the deposition at glancing angles or the incorporation of CF x species in the plasma discharge during film growth produces a decrease in the refractive index of the deposited silica films. The combined effect of the two experimental approaches further enhances the porosity of the silica films. Finally, the films prepared in a glancing geometry exhibit negative uniaxial birefringence.

On the Deposition Rates of Magnetron Sputtered Thin Films at Oblique Angles

“…Due to its stability, efficiency, and up‐scaling possibilities, magnetron sputtering (MS) deposition is nowadays one of the most popular techniques to grow thin films . Although this deposition method has been traditionally employed to grow highly compact and flat materials, new microstructural possibilities are being reported in the last years when operating at oblique angles; in this case, shadowing‐driven nanostructuration processes induce the development of highly porous structures, similar to those obtained in the absence of a plasma gas by e‐beam assisted depositions in this geometry . The MS technique, however, involves a higher degree of complexity associated to the plasma presence, and to the scattering events associated with sputtered particles present in the gas phase.…”

The Fabrication of a UV Notch Filter by Using Solid State Diffusion

“…This shows that thin film fabrications of (Al 2 O 3 /MgO) 8 Al 2 O 3 multilayers can be applied as notch filters through solid state diffusion. Solid state diffusion can make the diffusion index difference more gradual in a multilayer structure, which is advantageous in fabricating rugate filters [15,16].…”

High performance novel gadolinium doped ceria/yttria stabilized zirconia/nickel layered and hybrid thin film anodes for application in solid oxide fuel cells

“…The small amount of available material and the opacity of our films precluded conventional BET and optical measurements of porosity, respectively. However we have previously shown [19][20][21] by optical measurements on different but similarly deposited transparent oxide films that oblique angle deposition produces 35-40% porosity. That achieved in the present case is likely to be very similar.…”