ELECTROMIGRATION DAMAGE AND FAILURE DISTRIBUTIONS IN AL-4 WT PERCENT CU INTERCONNECTS

The spatial distributions of damage and failure are characterized in e ntire test lines under electromigration. The distribution of hillocks is random but that of voids is not, showing clear evidence for the rol es of temperature gradients (at the ends of the lines only) and of the near-bamboo microstructure. The evolution of void distributions is co nsistent with local microstructural observations on void splitting and coalescence. Mass flow from voids to hillocks is not detected in the damage distributions, but damage spacings do correlate with grain stru cture. Statistically valid characterization of damage and failure dist ributions can assist in identifying the controlling factors in the dev elopment of electromigration damage and failure. (C) 1998 American Ins titute of Physics. [S0021-8979(98)08517-X].