Effect on thermal stability of a Cu/Ta/Si heterostructure of the incorporatio of cerium oxide into the Ta barrier

초록

The effects of CeO<inf>2</inf> addition on the microstructural change of a Ta diffusion barrier film and thermal stability of the Cu/Ta/Si system were investigated. When a Ta layer was prepared with CeO<inf>2</inf> addition, the suicide formation was retarded up to 800 °C. The Cu/Ta+CeO<inf>2</inf>/Si system retained its structure up to 800 °C without an increase in stack resistivity, while the Cu/Ta/Si structure degraded after annealing at 550 °C. The Ta+CeO<inf>2</inf> diffusion barrier showed an amorphous microstructure and chemically strong bonds with Ta-Ce-O. It appeared that the thermal stability of the Cu/Ta+CeO<inf>2</inf> interface as well as the Ta+CeO<inf>2</inf>/Si interface was higher than that of both Cu/Ta and Ta/Si interfaces. Therefore, the Ta film prepared by CeO<inf>2</inf> addition effectively prevented the interdiffusion of Cu and Si through the diffusion barrier up to 800 °C. © 1998 American Institute of Physics.