Copper Oxidization Formation Analysis for Improving TDDB Reliability

Using Cu/SiOC interconnects, we investigated the relationship between the time dependent dielectric breakdown (TDDB) reliability and the cleaning process in copper chemical-mechanical polishing (CMP). We found that the formation of a non-uniform copper oxide film during post-CMP cleaning causes TDDB degradation when a barrier metal slurry that does not contain benzotriazole (BTA) is used. We also found the re-formation of a non-uniform copper oxide layer that accompanies the deionized water rinse is due to the dissolution of too much of the copper oxide film during the post-CMP cleaning process. For improved TDDB reliability, the uniform copper oxidization during post-CMP cleaning process is important in the Cu/low-k damascene formation process.