Integration of multi-level self-aligned CoWP barrier compatible with high performance BEOL

A hybrid CoWP/SiCN Cu passivation was integrated in a three-metal-level interconnect stack at 65 nm technology node using a porous ULK material (K=2.5). 5 and 20 nm thick Pd-free CoWP electroless barriers were evaluated using a standard trench first hard mask architecture (TFHM) integration scheme, with PVD, ALD or punch-through Ta-based metallization processes. This study evidenced strong interaction between CoWP and etching chemistries, inducing feature size modification. Results evidenced the successful integration of an ultra-thin electroless barrier with slight process tuning, whereas thicker one still requires specific etch process development or integration scheme modification