Investigation of interfacial reactions in monocrystalline and polycrystalline thin film couples of gold and silver by Auger depth profiling, transmission electron microscopy and measurement of contact resistance

Abstract

Interfacial reactions in monocrystalline and polycrystalline thin film couples of gold and silver were investigated by Auger depth profiling (ADP), transmission electron microscopy (TEM) and measurement of the contact resistance at temperatures ranging from 25 to 418°C in order to determine the effect of grain boundaries on concomitant kinetic processes. Results from both ADP and measurement of the contact resistance indicate that interfacial reactions are controlled by bulk interdiffusion, characterized by a mean activation energy of 1.45±0.10 eV, in monocrystalline couples and by grain boundary diffusion, characterized by an activation energy of 0.50±0.02 eV, in polycrystalline couples. Results from TEM reveal the formation of an interfacial network of dislocations in monocrystalline couples and the expansion of this network during subsequent interdiffusion. It is concluded that characterization of both chemical composition and microstructure, combined with measurement of concomitant electrical properties, provides a reliable description of degradation processes in thin film couples.