Test structure to evaluate the impact of neighboring features on stress of metal interconnects

The stress-inducing effects of neighboring metal interconnect features were studied using novel stressmigration test structures with various layouts of perpendicular neighboring combs. The structures with narrow widths showed no change in stressmigration performance, with or without near-neighbor structures. However, structures built with wider lines showed up to 3X worse stressmigration performance when perpendicular combs were present nearby, essentially independent of the spacing to the combs. Thus, near neighbor metal features were shown to be capable of degrading SM performance in some lines.