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Ultralow-dielectric-constant optical thin films built from magnesium oxyfluoride vesicle-like hollow nanoparticles

Nature Materials volume 6, pages 572–575 (2007)Cite this article

Abstract

Academic and industrial research groups are currently working to obtain high-quality transparent ultralow-refractive-index and ultralow-dielectric-constant thin films, as they are important for designing smart devices and systems for microoptics and microelectronics (for example, multilayer structures, optical resonators, photonic crystals, Cu interconnects, insulating layers and so on)1. Here, we report a robust and simple procedure to prepare highly porous and resistant semicrystalline magnesium oxyfluoride thin films through liquid deposition followed by a flash and short thermal treatment. These films are water insensitive, mechanically resistant (E=1 GPa), exhibit high optical quality and have an ultralow refractive index (n700 nm=1.09) and an ultralow dielectric constant (k100 kHz=1.6) which are required for the above-mentioned applications. Moreover, the process used to prepare these nanomaterials is well suited for industrial production on larger surfaces.

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Figure 1: Ellipsometric optical properties of the films versus relative humidity (water adsorption and desorption isotherms).
Figure 2: Contraction of the film thickness versus relative pressure and determination of the transversal Young modulus by modelling the continuous relaxation of the capillary stress at higher relative humidity using the Young–Laplace equation.
Figure 3: TEM images of the magnesium oxyfluoride network obtained after 10 min at 450 °C.

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Acknowledgements

The authors would like to thank C. Sinturel for XPS analyses, the low-k team at the CRCD Air-Liquide for the k-value determination, E. Bartel and N. Chemin for nanoindentation analyses, the European Network of Excellence FAME and the CNRS. The Centre of Electronic Microscopy of Orléans (France) is acknowledged for the TEM analyses.

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  1. Chimie de la Matière Condensée de Paris, UMR UPMC-CNRS 7574, Université Pierre et Marie Curie (paris 6), 4 place Jussieu, Tour 54-5E, 75252 Paris 05, France

    David Grosso, Cédric Boissière & Clément Sanchez

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  1. David Grosso
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  2. Cédric Boissière
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  3. Clément Sanchez
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Correspondence to Clément Sanchez.

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Grosso, D., Boissière, C. & Sanchez, C. Ultralow-dielectric-constant optical thin films built from magnesium oxyfluoride vesicle-like hollow nanoparticles. Nature Mater 6, 572–575 (2007). https://doi.org/10.1038/nmat1950

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