Laser shock-wave adhesion test (LaSAT) and ab initio calculations for adhesive strength evaluation of thin metallic films

In electronic devices, thin metallic films are generally deposited on brittle substrates such as silicon and quartz glass, which are chemically stable. As interfacial delamination causes the functional degradation of these materials, it is imperative to quantitatively evaluate their adhesion strength. In this study, Laser Shock-wave Adhesion Test (LaSAT) was developed, which could be performed in a non-contact manner. However, such brittle substrates are extremely weak under impact loading, making it difficult to conduct general LaSAT. Therefore, a multilayer specimen is developed to enable LaSAT, which successfully generates exfoliation of thin films from fused quartz substrates. The critical laser energy at which exfoliation occurred on various films was determined, and adhesion strength was quantitatively evaluated. In addition, to elucidate the delamination mechanism, the interface was modeled using first-principles calculations to clarify adhesion strength behavior.