Self-propagating exothermic materials for wafer bonding

Abstract

Metallic multilayer films made of light metal and transition metal (e.g. Al and Ni) with nanometer thicknesses can show self-propagating exothermic reaction by applying external energy, such as small spark or mechanical shock, during intermetallic compound formation. The exothermic characteristics can be controlled by changing the combination of atoms, atomic ratio, bilayer thickness, and total volume. We are using Al/Ni multilayer film as a heat source to melt low melting point material for wafer bonding. With this attractive functional material, wafer bonding can be made within a second. In this presentation, the exothermic characteristics of Al/Ni multilayer films, the representative results of wafer bonding, thermal resistance and strength measurement, and void and crack control experiments are introduced.