45nm-node Interconnects with Porous SiOCH-Stacks, Tolerant of Low-Cost Packaging Applications

The 45 nm-node interconnect with porous SiOCH-stacks of k_eff=2.9 is confirmed to have the practical reliability in PGBA and QFP. Adhesion strength of the via-ILD to the lower SiCN capping layer significantly impacts on the wire-bond reliability, but spreading the contact area of the bonding-wire within the fine-pitched bonding-pad suppresses the bonding failures in the low-k stack structures, irrespective of additional process of low-k curing or not. No failure was detected during reliability tests in PBGA package as well as QFP, confirming the practicality of the low k_eff interconnects for 45 nm-node ULSIs.