A model for the behaviour of tensile and compressive residual stresses developed in thin films produced by ion beam-assisted deposition techniques

Abstract

A theoretical model was developed in order to explain typical features of the in-plane residual stress behaviour of films deposited under particle bombardment. It was found that under a number of deposition conditions the stress will show a positive maximum (tensile stress) and will finally become negative (compressive) with increasing ion flux. But in other cases no maximum will be attained, and the stress will change smoothly from tensile to compressive values. The maximum possible tensile stress was found to decrease with increasing grain dimensions. Simple analytical expressions were derived which accurately describe the numerical results. The model reproduces a number of experimental facts on the stress behaviour, especially concerning the dependence on the ion flux and energy. Some other experimental data are discussed in the light of possible refinements of the model.