Microstructural analysis and mechanical properties of TaN-Ag nanocomposite thin films

TaN-Ag nanocomposite thin films with Ag nanoparticles dispersed in TaN matrix and surface were prepared by reactive co-sputtering of Ta and Ag in a plasma of N₂ and Ar. The films were then annealed using RTA (Rapid Thermal Annealing) at various annealing times and annealing temperatures to induce the nucleation and growth of Ag particles in the TaN matrix and on the film surface. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) were applied to examine the microstructure and surface morphology of TaN-Ag thin films. It is found that Ag tends to precipitate on the columnar boundaries when Ag concentration is low. In this case, the hardness as well as the resistance-to-crack can be enhanced. When Ag concentration is high, the TaN columnar structure is disrupted which can reduce the hardness and resistance-to-crack. Overall, the results reveal that the hardness and crack resistance of these films can be controlled by varying Ag contents and annealing conditions.