Evaluation of delamination strength of bonded micro-components: a nano-indenter technique combined with environmental microscopy

The strength against fracture initiation from an interfacial edge in bonded micro-components (Si/Cu and Cu/SiN) is quantitatively evaluated by using a novel technique that combines a minute mechanical tester (nano-indenter) and a special high-voltage transmission electron microscope (TEM) equipped with an environmental cell. The micro-component specimens having an interfacial edge of controlled geometry are prepared by a focused-ion-beam (FIB) based micro-sampling technique. The fracture initiation strength is particularly analyzed in terms of the fracture mechanics concept. In the case of Si/Cu interfacial edge, the scatter of strength value is significantly affected by the edge singularity: the higher singularity (wedged specimen) leads to the smaller scatter of strength. The effect of gaseous hydrogen (H2) on the strength of Cu/SiN is then evaluated by two kinds of wedged specimens. It is found that the strength is eminently reduced by the existence of H2 gas and, moreover, the strength reduction is dependent on specimen shape.