Conductive ultra-thin silver films are commonly fabricated by physical vapor deposition methods such as evaporation or sputtering. The line-of-sight geometry of these techniques impedes the conformal growth on substrates with complex morphology. In order to overcome this issue, volume deposition technologies such as chemical vapor deposition or atomic layer deposition are usually preferred. However, the silver films fabricated using these methods are generally non-electrically conductive for thicknesses below 20–50 nm due to island formation. Here, we demonstrate a novel approach for producing ultra-thin conductive silver layers on complex substrates. Relying on chemical vapor-phase deposition and plasma post-treatment, this two-step technique allows the synthesis of highly conductive and uniform silver films with a critical thickness lower than 15 nm and a sheet resistance of 1.6 Ω/□ for a 40 nm-thin film, corresponding to a resistivity of 6.4 μΩ·cm. The high infrared reflectance further demonstrates the optical quality of the films, despite a still large root-mean-square roughness of 8.9 nm. We successfully demonstrate the highly conformal deposition in lateral structures with an aspect ratio of up to 100. This two-step deposition method could be extended to other metals and open new opportunities for depositing electrically conductive films in complex 3D structures.

The control of nanometer-scale metallic silver particles morphology and their functional properties on a large scale represent a key factor for applications such as plasmonics, sensors, catalysts, or antimicrobial surfaces. The present work investigates in detail the growth of Ag nanoparticles deposited by plasma-enhanced atomic layer deposition (PE-ALD), from triethylphosphine­(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate)­silver­(I) [Ag­(fod)­(PEt3)C16H25AgF7O2P] as the Ag precursor and H2 as the reducing agent. The uniformity of the deposition in terms of nanoparticle morphology and chemical composition over a large surface area (8 in.) is analyzed using an original method. For all morphological, crystallographic, and chemical quantities, we report both the value at the center position and more originally, the gradient over a 10 cm distance on the substrate. The evolution of the gradient provides significant information on the growth mechanism. An effective growth rate of 0.020 ± 0.003 nm/cycle at 130 °C determined by energy-dispersive X-ray spectroscopy is found uniformly over the whole 8-inch area of the sample. According to X-ray diffraction and X-ray photoemission spectroscopy performed on the whole silicon wafer, the deposited material is made of polycrystalline pure metallic Ag, with a low amount of impurities emanating from the precursor, showing the completeness of the reduction reaction. Under self-limiting conditions, the effects of the chamber temperature and cycle number on the morphology of Ag nanoparticles deposited on silicon are analyzed. The results suggests that the Ag thin films mainly evolve following a material transfer. Two potential mechanisms are in competition: the migration of the particles and their further coalescence through the Volmer–Weber growth mode or a “surface Ostwald ripening”-like process. Under certain conditions, this last mechanism could explain the nonuniformity of the deposition.

The most promising materials to replace indium tin oxide (ITO) in transparent electrodes could be silver nanowires. One of the challenges is, however, the large-scale deposition of silver nanowires. This study provides a solution to deposit silver nanowires on large substrate area by spray deposition. The new concept is to spray on a heated glass substrate in vertical position with a flat spray beam instead of the basic conic beam. After optimization of the spray parameters such as the substrate cleaning, the droplets size, the pressure, and the spray distance, a surface of 100 cm 2 was fully covered with a very good homogeneity, and it was demonstrated that the concept can be extended on a much higher substrate area. The electrical and the optical properties of such a large sample were investigated by sheet resistance, transmittance, and haze factor measurements. A silver nanowire network with a sheet resistance of 9 Ω/sq, a visible transmittance of 91.7%, and a haze factor of 3.7% was deposited for a spray time of only 3 min for the 100 cm 2 area. The trade-off sheet resistance/haze factor showed similar and even better results than the ones published in the literature for smaller substrate area coverage by using other methods of deposition.