Electromigration critical length effect in Cu/oxide dual-damascene interconnects

Electromigration tests at temperatures between 340 and 400 degreesC and cur rent densities between 1.0 and 3.0 MA/cm(2) have been performed to determin e the temperature dependence of the critical length effect in 0.5-mum-wide Cu/oxide dual-damascene interconnects with 0.1 mum silicon nitride (SiNx) p assivation. A focused-ion-beam-induced contrast imaging technique is used t o locate failure sites of critical length test structures. Statistical anal ysis [E. T. Ogawa , Appl. Phys. Lett. 78, 18 (2001)] yields a threshold-len gth product (jL)(c), of 3700 A/cm, and a temperature dependence is not obse rved within the temperature range 340-400 degreesC. (C) 2001 American Insti tute of Physics.