Integrated circuit failure mechanism detected by IMMA

Unanticipated lateral field effect transistor (FET) action was observed between parts of an integrated circuit (IC) during electrical probing. Although comprehensive electrical investigation lead to the identification of potentially suspect areas, and reduced the possible origins of the problem to three, it was only after application of the techniques of ion microprobe mass analysis (IMMA) in the suspect areas that the problem was unambiguously identified. Based on this, a mechanism of failure was proposed which was subsequently confirmed by direct observation of the critical event.