Intrinsic stress in reactively magnetron sputtered metal-nitride/oxide films

Thin films deposited by physical vapor deposition (PVD) processes are generally in a state of mechanical stress, which can be regarded assumptionally as the sum of a external, thermal, and an intrinsic component. The external component can be neglected but a thermal component has to be considered, because of thermal input energies during film formation and possible differences in expansion between substrate and film material. The intrinsic component is understood to be the remaining structure sensitive part of the film stress. Therefore, the intrinsic mechanical stress represents a characteristic property of a film. Unpleasant macroscopic effects such as blisters in the case of compressive stress or cracks in the tensile case appear if the magnitude of the film stress exceeds either the adhesive force between film and substrate and/or the cohesive forces between film forming crystallites.