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.

This paper presents two cases utilizing high KeV Passive Voltage Contrast (PVC) for defect localization that is impossible with other techniques. The first case is thin layer resistor of CrSi. De-processing or polishing to expose the defective layer may damage it. High KeV PVC combined with FIB etch allows for a clear top view and x-section image. The second case involves a beam sensitive via chain. In order to avoid ion-beam-caused-damage, carbon paste was used to ground the sample. A high KeV electron beam was used to localize the defective via. This paper also discusses the way to avoid beam caused sample damage and how to apply it for further grounding and FIB cross sectioning to reveal the defect.