After the Cu CMP and post-CMP clean of the MET6 module, the top surface of the copper interconnects is exposed and highly susceptible to oxidation and outward metal diffusion P2.ILD 6-1 functions primarily as a dielectric diffusion barrier (DB) and copper capping layer (CCL) to seal the exposed Cu and Ta-based liner P2.Because the subsequent steps involve depositing the bulk ILD 6-2 and forming the bond pad cavity, ILD 6-1 must provide a robust hermetic seal against moisture ingress while acting