Unique Approaches to Isolate Nanoscale Defect in Snake-Comb Test Structure

Multiple techniques including electrical resistance measurement plus calculation, cross-sectional view of passive voltage contrast (XPVC) sequential searching, planar and cross-section STEM are successfully used to isolate a nanoscale defect, single metallic stringer in a snakecomb test structure. The defect could not be found by traditional failure analysis methods or procedures. The unique approach presented here, expands failure analysis capabilities to the detection of nanometer-scale defects and the identification of their root causes. With continuous shrinking feature sizes, the need of such techniques becomes more vital to failure analysis and root cause identification, and therefore yield enhancement in fabrication.