Reliability robustness of 65nm BEOL Cu damascene interconnects using porous CVD low-k dielectrics with k = 2.2

Reliability concerns over the applications of porous low-k dielectrics for Cu dual damascene (DD) interconnects have been dismissed with novel film formation methods, patterning approaches and structure designs. Results showed that the BEOL time dependent dielectric breakdown (BEOL TDDB) performance of interconnects built using porous CVD LK´s with k=2.2 and pore size ∼2.8nm were not comprised with film pore integrity retained to have TDDB T₆₃ predicted to be 1 × 10⁹ yrs at 0.3 MV/cm and 125°C. Further investigations also revealed that the impacts of weak mechanical and poor thermal properties associated with the LK material on its interconnect electromigration and stress migration performances can be demolished through various interface engineering with EM lifetimes of 0.12 μm Cu lines or 0.13 μm vias at 1 MA/cm² and 110°C longer than 400k hrs or 150k hrs, and SM failure rate = 0 (>100% Re shift) for vias on all test structures after thermal annealing at 150°C for 500 hrs.