Analysis of Post-Chemical-Mechanical-Polishing Cleaning Mechanisms for Improving Time-Dependent Dielectric Breakdown Reliability

Abstract

Using 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 nonuniform copper oxide film during post-CMP cleaning causes TDDB degradation when a barrier metal slurry that does not contain benzotriazole is used. We also found the reformation of a nonuniform 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 the post-CMP cleaning process is important in the damascene integration process.