Composite Dielectric/Metal sidewall barrier for Cu/porous ultra low-k damascene interconnects

The integration of Cu metallization with porous ultra low-k dielectrics requires a more robust diffusion barrier than the conventional physical vapor deposited (PVD) Ta or TaN barrier. In this work, a composite sidewall diffusion barrier consisting of dielectric/metal bilayer structure is successfully integrated in Cu/porous ultra low-k interconnects to improve the interconnect performance and reliability. With the use of a thin Al stuffing layer between Ta and the dielectric layers, further improvements in the interconnect performance and reliability are achieved.