Investigation of stress induced voiding and electromigration phenomena on direct copper bonding interconnects for 3D integration

We investigate for the first time the reliability of the direct copper bonding process. Electromigration (EM) and Stress Induced Voiding (SIV) tests are performed on intensive 30000 daisy chains and emphasize the good behaviour facing the risk of reliability issues in Cu/Cu bonded interconnects achieved by a direct low temperature (200°C) bonding. Furthermore, a comparison between stand alone and bonded device shows that the metallic bonding interfaces do not impact on the failure mechanism during EM tests.