The influence of moisture on Cu line electromigration (EM) behavior of dual damascene interconnection is reported. The authors have found that moisture has a negative influence on EM behavior, but it depends on the seal-ring structure located along the peripheral of the test pattern. The reduced Cu lifetime, observed for tested samples without seal-ring structure, was due to lateral moisture penetration. Lateral moisture diffusion was considered an effective mechanism for deteriorating the Cu interface during the die-sawing processing for structures without seal-ring layout. As a result, the seal-ring layout is effective and essential in Cu/low-dielectric (low-k) material integrity to prevent moisture penetration during the package procedures. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3501127]