Magnetically actuated peel test for thin films

Delamination along thin film interfaces is a prevalent failure mechanism in microelectronic, photonic, microelectromechanical systems, and other engineering applications. Current interfacial fracture test techniques specific to thin films are limited by either sophisticated mechanical fixturing, physical contact near the crack tip, or complicated stress fields. Moreover, these techniques are generally not suitable for investigating fatigue crack propagation under cyclical loading. Thus, a fixtureless and noncontact experimental test technique with potential for fatigue loading is proposed and implemented to study interfacial fracture toughness for thin film systems. The proposed test incorporates permanent magnets surface mounted onto micro-fabricated released thin film structures. An applied external magnetic field induces noncontact loading to initiate delamination along the interface between the thin film and underlying substrate. Characterization of the critical peel force and peel angle is accomplished through in situ deflection measurements, from which the fracture toughness can be inferred. The test method was used to obtain interfacial fracture strength of 0.8-1.9 J/m2 for 1.5-1.7 μm electroplated copper on natively oxidized silicon substrates.

► Non-contact magnetic actuation test for interfacial fracture characterization.
► Applied load is determined through voltage applied to the driving electromagnet.
► Displacement and delamination propagation is measured using an optical profiler.
► Critical peel force and peel angle is measured for electroplated Cu thin-film on Si.
► The measured interfacial fracture energy of Cu/Si interface is 0.8-1.9 J/m2.