METAL ELECTROMIGRATION DAMAGE HEALING UNDER BIDIRECTIONAL CURRENT STRESS

The ac electromigration lifetime, without dc component, has been studied in a wide frequency range (mHz to 200 MHz), and is found to be linearly proportional to the repetition frequency of the ac stressing current. This behavior is observed in both of the metalization systems (Al-2% Si and Cu) investigated. This provides further confirmation that ac lifetime is orders of magnitude longer than dc lifetime and CMOS signal lines may be called upon to carry much larger current than allowed in the present practice.