Copper Diffusion Improvement by Optimizing TaN and Integration in Power Device

Copper (Cu) interconnect has been widely used for large scale integrated circuits in logic process technology nodes of 90 nm and beyond. Tantalum nitride (TaN) as the barrier film plays a significant role in device reliability. TaN film prevents Cu diffusion into the Al bond-pad layer and the dielectric layer which will lead to voids in top metal Cu as well as circuit leakage increase that impacts product yield and reliability. Therefore, it is very important to optimize TaN film in back-end of line (BEoL) integration. In this study, TaN film's barrier ability to prevent Cu diffusion was investigated. These results indicate that Cu diffusion can be improved by tuning TaN film barrier properties as well as optimizing process integration flow.