The size limit of Al/Ni multilayer rectangular cuboids for generating self-propagating exothermic reaction on a Si wafer

In this study, the size limit of Al/Ni nano-multilayered rectangular cuboids for the self-propagation of their exothermic reaction on a Si wafer was investigated. After Al/Ni multilayer films were deposited on a Si wafer, micro-sized rectangular cuboids were formed from the films using focused ion beam. By applying a small spark to the cuboids, we have tried to make them exothermic reaction. As the result, both of reacted and unreacted cuboids were found. In the cuboids with higher aspect ratio and smaller one-side length, the reaction easily occurred. The cause of the size effect was discussed in the viewpoint of thermal conductivity of a Si substrate.