A key of self-formed barrier technique for reliability improvement of CU dual damascene interconnects

We have studied key factors of Ti-based self-formed barrier technique on interconnect reliability. A performance of time dependent dielectric breakdown shows superior endurance, using quite a thin Ti-based self-formed barrier. However, to achieve a superior electromigration performance using Ti-based self-formed barrier, much more amount of Ti is needed compared with that of TDDB performance. This is why the control of excess Ti atoms is important to suppress the electromigration. We also discuss the mechanism that why the excess Ti improve reliability performance.