Suppression of stress-induced voiding in copper interconnects

Studied stress-induced voiding in Cu interconnects in the temperature range below 250/spl deg/C, and found two different voiding modes. One mode occurs inside a via having wide wire above it, and can be suppressed by optimizing the via shape and the via-cleaning process. The other mode occurs under a via having wide wire below it and can be suppressed by increasing the Cu grain size and improving the adhesion of the barrier metal with Cu.