ICMCTF2016 Session HP: Symposium H Poster Session

Thin film technology is pervasive in microelectronics, and in optical, magnetic or micro-mechanical devices. However, the mechanical stability of such nanoscale structure is crucial for applications since it is related to device lifetime. Furthermore, the mechanical behavior of nanostructured materials is still not well known. In order to study size effect, nanostructured thin films have been elaborated by sequenced ion beam sputtering. The grain size is controlled by stopping the grain growth during the thin film growth [1]. Using a biaxial tensile setup developed on the DiffAbs beamline at synchrotron SOLEIL [2], we performed x-ray diffraction (XRD) measurements during controlled biaxial deformation tests on gold thin films deposited on Kapton substrate. Strain analysis of different types of gold thin films with different grain size and architecture has been performed during different proportional loadings using the sin²ψ method. The resulting gold Bragg peak shifts are monitored thanks to a 2D detector. XRD allows measuring the intra-granular strains using the so-called sin²ψ method while the macroscopic in-plane strains are measured simultaneously thanks to Digital Image Correlation. The average method [3] has been applied to extract the evolution of the elastic strains from the sin²ψ curves which are then plotted versus macroscopic strains in order to extract the elastic limit. By analyzing the mechanical response of the different films [4], we conclude that gold thin films follow a plastic deformation mode whatever the grain size or thin film architecture.

[1] Girault. B, Eydi. D, Goudeau. P, Sauvage. T, Guerin. P, Le Bourhis. E, Renault. P.O., Journal of Applied Physics (2013) 113, 174310

[2] Geandier. G, Thiaudière. D, Randriamazaoro .R. N., Chiron. R, Djaziri. S, Lamongie. B, Diot. Y, Le Bourhis .E, Renault .P. O., Goudeau .P, Bouaffad .A, Castelnau .O, Faurie .D, Hild .F, Review of Scientific Instruments (2010) 81, 103903

[3] Faurie. D, Renault. P.O, Le Bourhis. E, Chauveau. T, Castelnau. O, Goudeau. P, Journal of Applied Crystallography (2009) 44, 409-413

[4] Djaziri. S, Faurie. D, Renault. P.O, Le Bourhis. E, Goudeau. P, Geandier. G, Thiaudière. D, Acta Materialia (2013) 61, 5067-5077

In this paper we used capacitance gradient map (∂C/∂z) arising of Kelvin probe force microscopy (KPFM) and confocal-Raman spectroscopy map to identify TiO₂ nanoparticles, distributed in anatase phase, between two layers of Diamond-like carbon (DLC) film. The sample was used to compare the ∂C/∂z and regular KPFM images used to identify electrical properties of TiO₂ buried a few nanometers from the top. In a single-pass of KPFM scanning: topography, surface potential, and ∂C/∂z maps were acquired simultaneously. From confocal-Raman spectroscopy analyses, the signature of anatase phase where also identified. For sample preparation, a thin layer of DLC was first deposited on a silicon substrate by plasma enhanced chemical vapor deposition (PECVD). After DLC deposition, the surface was treated with nebulizer vapor in air environment containing alcohol and nanoparticles of TiO₂ in anatase phase. The vapor was produced in ultra sound under laminar flow. The nanoparticles of TiO₂ were then anchored in the DLC matrix by means of an additional thin DLC layer produced by PECVD deposited over the TiO₂ nanoparticle. The finished sample comprised silicon substrate with DLC -TiO₂-DLC. These procedures allow us to infer the uniformity of chemical domains distributed in an amorphous film enabling a correlation with the correspondent surface potential obtained by ∂C/∂z and confocal maps.