Effect of inter-level dielectrics on electromigration in damascene copper interconnect

The impact of dielectric materials on the reliability of advanced copper (Cu) interconnect is of growing importance. The effect of barrier dielectrics and low-k materials of Inter-Level Dielectric (ILD) on the electromigration (EM) in the line and via-line structure of dual-damascene Cu interconnects was analyzed. The resulting electromigration behavior can then be attributed to Cu barrier layer or low-k dielectrics, depending on the test structure. The SiN barrier layer showed a better electromigration endurance compared to SiC barrier layer for narrow Cu line structure. We had also observed that the carbon-doped oxide (CDO) low-k samples had a higher drift velocity, which results in less electromigration endurance on the via-line structure compared to fluorosilicate glass (FSG).