Residual stress in physically vapor deposited films: A study of deviations from elastic behavior

Abstract

The residual stress in films made by plasma-enhanced physical vapor deposition is generally very high, of the order of 1% of the shear modulus. The present work is a report of a study of the lattice parameter and the residual stress as measured by X-ray diffraction (XRD) methods on different crystal planes. ZrN films are studied on stainless steel substrate; these films are considered typical of group IVB nitride films and were used as a model system of practical significance. Deviations from simple behavior after a heat treatment are found on the (111) and (200) families of planes but not on high index planes. The deviations are discussed in terms of plastic deformation, shear stresses and microcracking on these planes which are the primary and secondary slip systems respectively. The residual stress in the substrate is low, in contrast to what would be expected from the high stress in the film. The XRD data appear to indicate that the effect of this stress is absorbed, at least in part, by plastic deformation on the (200) planes of the stainless steel substrate; unfortunately the present experimental arrangement did not permit the (111) primary slip plane to be studied.