Assessment of copper contamination impact on inter-level dielectric reliability performed with time-dependent-dielectric-breakdown tests

Abstract Time-Dependent-Dielectric-Breakdown (TDDB) tests have been conducted on differently copper-contaminated Metal-Oxide-Silicon (MOS) capacitors in which the insulator was the same as the interconnects Inter-Level Dielectric (ILD). TDDB tests are particularly sensitive in addressing the properties of Cu-contaminated dielectric and they are suitable for the characterization of diffusion barrier layers for Cu based intconnects. The lifetime dependence of ILD on Cu contamination clearly shows that the lost of insulating performances can be a new degrading mechanism related to Cu-based interconnects. It is also shown that technological process steps could impact the reliability of Cu interconnects: without effective cleaning steps any effort made in providing strong diffusion barrier could vanish.