EFFECT ON THERMAL-STABILITY OF A CU TA/SI HETEROSTRUCTURE OF THE INCORPORATION OF CERIUM OXIDE INTO THE TA BARRIER/

The effects of CeO2 addition on the microstructural change of a Ta dif fusion barrier film and thermal stability of the Cu/Ta/Si system were investigated. When a Ta layer was prepared with CeO2 addition, the sil icide formation was retarded up to 800 degrees C. The Cu/Ta + CeO2/Si system retained its structure up to 800 degrees C without an increase in stack resistivity, while the Cu/Ta/Si structure degraded after anne aling at 550 degrees C. The Ta + CeO2 diffusion barrier showed an amor phous microstructure and chemically strong bonds with Ta-Ce-O. It appe ared that the thermal stability of the Cu/Ta + CeO2 interface as well as the Ta+CeO2/Si interface was higher than that of both Cu/Ta and Ta/ Si interfaces. Therefore, the Ta film prepared by CeO2 addition effect ively prevented the interdiffusion of Cu and Si through the diffusion barrier up to 800 degrees C. (C) 1998 American Institute of Physics.