Grain Structure and Electromigration Testing of Deep Sub- Micrometer Cu Interconnects

Abstract

AbstractCopper interconnect test stripes were fabricated by electron-beam lithography, evaporation and lift-off to linewidths as small as 140 nm. Grain structure in the as-deposited films exhibited smaller standard deviation than long-term annealed films. Grain growth during the anneal step increased maximum grain size by 2.5 times. Electromigration lifetime testing indicated these interconnects have 2-4 orders-of-magnitude greater normal-use lifetimes than large cross-sectional area, large-grain Al-alloy interconnects.