Evaluation of Interface Toughness Between Submicron Island and Substrate

Micro-electronics and micro-mechanical devices consist of low-dimensional components such as islands, lines and films, and they have many intrinsic bi-materials interfaces. Stress concentration near an interface edge due to the deformation mismatch sometimes causes delamination, which brings about fatal malfunction of the device. On the other hand, the size required for the components becomes submicron-scale in order to shrink the device. It is necessary, therefore, to evaluate the interface strength among the submicron-components and the substrate. The size of the stress-concentrated region near an interface edge, which affects the delamination crack initiation, is dependent on the length scale; the field shrinks as the size of the component decreases [

1

]. For submicron-components, the region size also becomes submicron-meter order. It is not clear whether such a small region actually dominates the delamination or not. The purpose of the study is to elucidate the mechanism dominating the crack initiation at the interface edge between a submicron island and a substrate.