The contributions of the “interface” on interconnect reliability are investigated in some previous work. For electromigration and stress-induced voiding, Cu/dielectrics interface has a key role as a dominant diffusion path of Cu. A surface treatment after chemical mechanical polishing affects lifetime distribution of time-dependent dielectric breakdown. The defect density on the interface is a key factor to control the early failure. In this paper, some advanced metallization process and its effects to suppress the reliability issues are introduced. To adapt the novel process technologies successfully in product line, these results will provide valuable information.