Effects of CeO₂ incorporation on the performance of a Ta diffusion barrier for Al metallization

The effects of CeO₂ incorporation on the performance of a Ta diffusion barrier in the Al/Si system were investigated in the temperature range of 450-550°C. When Ta film was deposited without CeO₂ incorporation, the reaction between Ta and Al occurred at 500°C, leading to the formation of Al₃Ta. In the case of CeO₂-incorporated Ta barriers, however, the reaction between Ta and Al was suppressed up to 550°C. The suppression of the reaction of Ta with Al was attributed to the strong chemical bonding of Ta-Ce-O or Ta-O and the amorphous-like microstructure of the CeO₂-incorporated Ta barrier, followed by the reduction of the chemical driving force for the initial stage of Al₃Ta formation.