Downscaling metal-dielectric interface fracture experiments to sub-micron dimensions: A feasibility study using TEM

In this study a bending beam approach is miniaturized to the sub-micrometer size regime for in-situ transmission electron microscopy (TEM) investigations. The purpose of this study was to evaluate the feasibility of this method for determining interface fracture energies for metal-dielectric systems, which are comparable to other methods. The interfaces under investigation are Cu/borophosphosilicate glass (BPSG) and W(20 at.% Ti)/BPSG as examples for a weak and a strong interface, respectively. It was possible to fracture the Cu/BPSG interface during in-situ TEM experiments and to obtain estimates for the interface fracture energy comparable to literature values. However, the TEM approach imposes challenges which can complicate the determination of an interface energy release rate; these influences are discussed. The miniaturized TEM approach failed for W(20 at.% Ti)/BPSG because no interface fracture occurred in this case. Thus it is concluded, that the experimental setup of the in-situ TEM bending beam method utilized in this study is useful for weak interfaces but for strongly adhering interfaces it is inappropriate.