Optimization of metallization processes for 32-nm-node highly reliable ultralow-k (k=2.4)/Cu multilevel interconnects incorporating a bilayer low-k barrier cap (k=3.9)

Reliability of 32-nm-node ultralow-k (k=2.4)/Cu multilevel interconnects incorporating a bilayer low-k barrier cap (k=3.9) was improved without excessive wiring resistance by using CuAl seed technology with high-temperature and short-time annealing. Though the increase in wiring resistivity was about 10 %, both electromigration (EM) and stress-induced voiding (SiV) reliability was clearly improved by using Cu-0.5wt%Al seed metal.