Inducing stable interfacial delamination in a multilayer system by four-point bending of microbridges

The ability to produce stable delamination of thin film multilayer interfaces is a powerful tool for studying the interfacial adhesion within microsystems. In this study, a technique involving the four-point bending of microbridges was applied to initiate stable interfacial delamination within a multilayer system. Microscale pre-notched bridges with clamped-ends were machined into an Al/SiN/GaAs multilayer using focus ion beam milling. A square flat-end indenter was used to induce bending of the bridge by two contact locations. Bridge failure occurred via substrate fracture at the pre-notch, followed by crack deflection, and stable interfacial delamination of the SiN/GaAs interface. Substrate fracture and delamination were identified within the obtained load-displacement curves as a pop-in and region of linear load reduction respectively.