Failure of a thin film due to inclusions on the interface

This paper addresses failures near irregularities on the interface between a film and a substrate. Several boundary value problems, including two-dimensional and three-dimensional problems, involving inclusions of various shapes placed on the interface, are considered. The loading is induced by the lattice parameter mismatch between the film and substrate. Stresses near the interface and the inclusion boundary are of particular interest. The solutions show stress concentration around the inclusion boundary ; in fact, a logarithmic singularity exists at the intersection of the inclusion, film and substrate. Emphasis is placed on identifying failures associated with high stresses near the inclusion. A theoretical prediction of the misfit strain to cause adhesion failure is obtained. The driving force for dislocation emission from the inclusion is calculated, and it is shown that dislocation emission from inclusions is favoured under a sufficiently large misfit strain. © 1997, Elsevier Science Ltd. All rights reserved