Highly reliable dielectric/metal bilayer sidewall diffusion barrier in Cu/porous organic ultra low-k interconnects

A robust dielectric/metal bilayer sidewall diffusion barrier, using a-SiC:H as the dielectric layer and Ta as the metal layer, was integrated with Cu/porous organic ultra low-k damascene structure. The reliability and electrical performance of a-SiC:H/Ta bilayer barrier were significantly better than the conventional physical vapor deposition (PVD) multi-stacked Ta(N) metal barrier. The plasma enhanced chemical vapor deposition (PECVD) a-SiC:H layer is able to effectively seal the rough surface of porous low-k material, resulting in improved electrical performance and reliability.