Role of an interface crack for the blistering mode of a stiff film on a compliant substrate

A stiff thin film deposited over an underlying compliant substrate is susceptible to blistering when it is subjected to excessive in-plane compressive stresses. Two kinds of blistering modes (wrinkling and buckling) have been revealed in experiments, depending on the properties of film/substrate pair as well as that of interface adhesion. The purpose of this work is to quantify the role of an interface crack for the selection of such blistering modes in compressed thin films. By a semi-analytical approach, the transitional size of an interface crack is identified at which both wrinkling mode and buckling mode may arise. The mode selection diagram is constructed and characterized with respect to the normalized interface crack size and compressive strain. The theoretical estimations are validated by a finite element method incorporating an interface cohesive zone model and are demonstrated to be in reasonable agreement with experimental observations in previous literature. The results in this work are expected to be helpful in the effective design and evaluation of thin-film devices.