Effects of Sputtering Bias on the Material Characteristics of Ag Nanotwinned Films

Abstract

The mechanisms of the formation of nanotwinned structures have recently attracted attention due to the advantageous properties of the structures. This paper describes the microstructural evolution of (111)-oriented nanotwins into huge (200)-oriented grains with grain sizes exceeding the film thickness. The results reveal that the initiation temperature for abnormal grain growth can be improved to nearly 300 °C by altering the microstructure of the nt-Ag films with the application of substrate bias during deposition. Densification of the nt-Ag films by substrate bias reduces the number of fine equiaxed grains in the transition layer and hence reduces the overall grain boundary energy of the nt-Ag film. The lower number of discontinuities that form within the nanotwinned layer retards the lateral growth of the columnar grains. The combination of the effects is conducive to the thermal stability of Ag nanotwinned films, implying promising future applications in microelectronics.