Effects of Fowler Nordheim tunneling stress vs. Channel Hot Electron stress on data retention characteristics of floating gate non-volatile memories

Abstract

Data Retention continues to be a reliability concern for flash memories, especially given the challenge of characterizing the lifetime for stress induced mechanisms like Low Temperature Data Retention (LTDR) that can not be accelerated using conventional means. There have been numerous reports on this mechanism, which have for the most part attributed the leakage to the stress from Fowler Nordheim Tunneling (FNT). In this report we apply E-field acceleration methods to large memory arrays to compare the anomalous leakage rate following FNT to that produced by Channel Hot Electron (CHE) stress. We show that the oxide leakage following CHE stress exhibits characteristics similar to that from FNT stress although at a reduced rate. The leakage from CHE stress should be included with other considerations related to LTDR when scaling floating gate NVM technologies.