Wack Sabrina, Lunca Popa Petru, Adjeroud Noureddine, Vergne Christèle, Leturcq Renaud
Materials Research & Technology (MRT) Department, Luxembourg Institute of Science & Technology (LIST), L-4422 Belvaux, Luxembourg.
ACS Appl Mater Interfaces. 2020 Aug 12;12(32):36329-36338. doi: 10.1021/acsami.0c08606. Epub 2020 Jul 29.
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.
导电超薄银膜通常通过物理气相沉积方法制备，如蒸发或溅射。这些技术的视线几何形状阻碍了在具有复杂形态的衬底上的保形生长。为了克服这个问题，通常首选化学气相沉积或原子层沉积等体沉积技术。然而，由于岛状形成，使用这些方法制备的银膜在厚度低于20 - 50 nm时通常不导电。在这里，我们展示了一种在复杂衬底上制备超薄导电银层的新方法。依靠化学气相沉积和等离子体后处理，这种两步技术能够合成高导电性且均匀的银膜，其临界厚度低于15 nm，对于40 nm厚的薄膜，方阻为1.6 Ω/□，对应电阻率为6.4 μΩ·cm。尽管均方根粗糙度仍高达8.9 nm，但高红外反射率进一步证明了薄膜的光学质量。我们成功地展示了在高达100的纵横比的横向结构中的高度保形沉积。这种两步沉积方法可以扩展到其他金属，并为在复杂三维结构中沉积导电膜开辟新的机会。
