“…Also, voids within the IMD or voids on top within the capping dielectric layer have been seen, but their appearance after breakdown may depend upon the capping dielectric composition [298]. Specialized failure analysis techniques -such as transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX or EDS), or electron energy loss spectroscopy (EELS), or secondary ion mass spectroscopy (SIMS) line scans -may be used to assess the presence of unusual nanoscopic defects found after TDDB stress [238,301,302]. Because the electric field is typically highest at the trench top, damage is usually found to be concentrated in that area of the test structure crosssection, unless there is a case where another damage path has triggered failure, such as when metal barrier failure has occurred [93,299].…”