Structure, stresses and stress relaxation of TiN/Ag nanocomposite films

Morphology, structure and thermal behavior of magnetron sputtered TiN/Ag nanocomposite thin films deposited at 150 degrees C with an Ag content in the range of 7 to 45 at% were characterized. The films were thermally cycled and the relationship between Ag content, film structure and stress development is analyzed. The results indicate that the residual stresses in as-deposited films and the behavior during heating are determined by the film structure and the plastic deformation of the Ag phase. The increasing plastic deformation with increasing Ag content causes significant changes in the stress-temperature behavior. While films with low Ag content show a plateau in compressive stress from deposition temperature up to 280 degrees C followed by stress relaxation, films with higher Ag content exhibit a zero stress level from deposition temperature up to the maximum annealing temperature. During cooling, all films exhibit linear thermo-elastic behavior, where the slope of the stress-temperature curves also depends on the Ag content.