Effects of Al3Ta/TaN Bilayered Diffusion Barriers in the Al/Si Contact Systems

Abstract

A thermally stable contact system of Al/Al₃Ta/TaN/Si, which tolerates post-metallization annealing even at 600° C for 1 h, was successfully prepared by achieving a state of chemical pseudo-equilibrium at the interface of Al/Al₃Ta and that of Al₃Ta/TaN. No solid-phase reactions took place at these interfaces due to the realization of minimum free energy states. The thermal stability of the interfaces in the contact system was discussed from the point of view of the solid-phase reaction of thin films. It was also revealed by X-ray diffraction analysis that the absence of structural change due to grain growth in both the TaN and Al₃Ta layers by annealing is effective for the total stability of the contact system. We have been successfully able to demonstrate the validity of realizing the chemical pseudo-equilibrium interfaces for preparing thermally stable contact systems.