Integration of gas cluster process for copper interconnects reliability improvement and process impact evaluation on BEOL dielectric materials

A new process, based on the interaction between Si and N rich gas cluster and post Cu CMP features surface, was integrated in a multi-level Cu interconnect stack using 65 nm design rules. Using the same integration scheme as stand-alone SiCN dielectric capping, excellent electrical properties were achieved when the process was implemented with a USG layer on top of a porous Ultra-Low K. Furthermore, 3x electromigration time to failure improvement was evidenced, making the approach very promising to address EM performance requirement for the most advanced technology nodes. Moreover, contrary to PE-CVD CuSiN approach, the process does not depend on Cu crystallographic orientation. Finally, when the implantation process is performed on un-capped ULK, a deep N contamination occurs. Therefore, the process must be optimized to preserve the interest of this technique for the most aggressive architectures.