Effects of linelength and bend structure on electromigration lifetime in Al-Cu submicron interconnects

The authors systematically study the dependence of electromigration lifetime on linelength and the number of bends in Al-Cu submicrometer lines. It is shown that, as the linelength increases from 10 to 50 mu m, the lifetime decreases slightly and then levels off at a linelength of 500 mu m. The independence of lifetime from linelength in Al-Cu submicrometer lines longer than 100 mu m can be understood by assuming that electromigration-induced failure is caused by intrinsic defects. The lifetime was also found to decrease almost linearly with an increasing number of bends in Al-Cu submicrometer lines. The effect of bend structure on the lifetime is discussed in terms of current crowding at the bend structure.<>