Evaluation of Interfacial Fracture Strength in Micro-Scale Components Combined with High-Voltage Environmental Electron Microscopy

Abstract

A novel experimental method that enables evaluation of interfacial strength of micro-components subjected to well-controlled various environments is proposed. The method combines a high-voltage transmission electron microscope (HVEM) equipped with an open type environmental cell (EC) and a quantitative nano-mechanical holder. The experiments were conducted by using focused-ion-beam-processed micro-cantilever specimens containing interfaces of dissimilar materials (silicon (Si) and copper (Cu)). The in situ observation of fracture phenomenon along a target interface (Si/Cu) and the simultaneous measurement of fracture load were successfully implemented under vacuum and gaseous environments (N2 gas and N2/H2 mixed gas) whose maximum pressure was controlled at 5 × 103 Pa. The stress distribution at the onset of fracture was calculated in detail by finite element analysis. The strength against interfacial debonding was then evaluated by the local normal stress value at the interface free-edge. The proposed technique, which can also be combined with simultaneous electron probe analyses, is highly versatile when compared to the conventional nano-mechanical strength evaluations under limited environments.