I. Österreicher, S. Eckl, Infineon Technologies Dresden GmbH & Co. OHG, Dresden, Germany; B. Tippelt, S. Doering, W. Werner, Qimonda Dresden GmbH & Co. OHG, Dresden, Germany; R. Prang, Qimonda Dresden GmbH & Co. OHG, Dresden, Germany

Summary: A new class of soft defects was analyzed on chips that proved to be functional under any condition but showed delta Iddq variations at certain scan vectors. The failure analysis flow was adapted to this kind of “soft fails” that may cause potential reliability problems. Physical Failure Localization was performed which showed emission spots at positions that were inconspicuous on dies with constant Iddq consumption. Atomic Force Probing proved a transistor Source-Drain leakage which was obviously not high enough to cause a functional fail but revealed itself in small current variations. The leakage current was attributed to a defective CA-contact interface.