The effect of copper (Cu) barrier film deposition process on the Cu interconnects was investigated, including the waiting time between Cu chemical mechanical polishing and the barrier dielectric deposition, the preheating time, ammonia (NH3) plasma treatment prior to the barrier dielectric deposition, and various types of barrier dielectric. Effective treatment on the Cu surface ensures superior conductivity of the Cu interconnects and enhances the adhesion between Cu and the barrier film, causing a longer electromigration failure time. However, excessive thermal time (preheating, treatment, and deposition time) induces the Cu hillock defect. Furthermore, silicon nitride (SiN) film with a lower hydrogen content has better physical and reliability performances. Therefore, optimization of the Cu barrier deposition process is important to improve the performance of Cu interconnects. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3425631]