The impact of the bilayer TaN/Ta barrier at the copper seed and copper electroplating process in semiconductor fabrication

Copper metallization process, using electroplating, in Integrated Circuit interconnect, poses big challenge in semiconductor fabrication. Besides the stringent Dual Damascene requirement, the copper material itself is prone to rapid interface diffusion as well as surface oxidation. Thus the copper metallization process has to be performed within specific time after copper seed deposition process. This study investigated the impact of bilayer TaN/Ta barrier on copper sheet resistance changes at different time intervals. The study was based on 200mm wafer. In addition to that, correlation between sheet resistance to other copper film properties such as reflectance and stress was also investigated. Based on results of this study, bilayer TaN/Ta barrier inclusion in copper seed greatly improved film sheet resistance stability.