Reliability and conduction mechanism study on organic ultra low-k (k=2.2) for 65/45 nm hybrid Cu damascene technology

We have developed an integrated approach for Cu/hybrid low k interconnects. Implementation of this method to 65/45 nm dual damascene was performed using a hybrid film stack consisting of porous SiLK (p-SiLK, k=2.2) and CVD SiOC (k=3.0). The damage to p-SiLK in plasma clean is prevented by pore sealing and an effective k value as low as 2.6 was extracted from the bias temperature stress (BTS) experiments. From BTS, it is found that Frenkel-Poole (FP) emission dominates the leakage mechanism in p-SiLK. The proposed hybrid approach demonstrates ∼21% reduction in RC product and shows excellent electrical and reliability (EM and SM) performance comparable to the conventional Cu/SiOC (k=3.0) damascene.