Abstract
Interfaces between different phases are of significant fundamental interest and play an important role in many areas of technology. This is particularly true for interfaces between highly dissimilar phases of very different chemical composition and atomic structure. In this work, the Cu-Ta system studied is a good example of such dissimilar phases, since Cu and Ta have practically zero mutual solid solubility, have different crystal structures (fcc Cu versus bcc Ta), as well as highly different melting temperatures, mechanical strength, chemical reactivity, and many other properties. The Cu-Ta system is also relevant to microelectronic systems, since Ta thin films can be used diffusion barriers separating Cu conductor lines from the semiconductor substrate in integrated circuits.