Characterization of split gate flash memory endurance degradation mechanism

In this paper, the weak erase failure mechanism of a source side injected split gate flash memory after endurance (ENDU) cycling test has been identified through a 2T cell structure. In general, charge trapping in the inter poly oxide (IPO) after Fowler Nordheim tunneling erase is considered to dominate the weak erase failure. However from this study, it is found that cell current reduction after erase is not due to erase-induced tunneling oxide degradation. On the contrary, program-induced electron trapping in the coupling oxide dominates the cell current reduction after long term endurance cycling stress.