A New Oxide Damage Characterization Technique For Evaluating Hot Carrier Reliability Of Flash Memory Cell After P/E Cycles

Abstract

Interface state generation and oxide trap charge creation have been recognized as a major reliability issue for Flash memory cells [l-21. In a certain design of Flash cells, programming of the cell is achieved by hot-carrier programming near the drain, while erase is performed by F-N tunneling near the source. Both will generate the so-called oxide damages, which include the interface state Nit and the oxide trap charge Q,,. They will cause serious reliability problem such as programming delay, window closure, and gate disturb etc. So far, these characteristics can only be observed from measurement. Their correlation with oxide damages has not been clear since the profiling of these damages are rather difficult and not available. In this paper, a new and simple technique which allows the profiling of both interface states (Nit) and oxide charge (Qox) generated during either programming or erase will be presented. The effects of these damages on the flash cell performance and reliabilities will then be identified.