Abstract
This article represents a new method for Data Retention failure (DR) in
NAND Flash memories by analyzing the charge leakage phenomena.
Retention failure accrue when stored data changes its level. This
usually happens at and because of a high temperature environment that
accelerate leakage.
The amount of electron charge in the cell is rather hard to calculate.
However, we know that a verification process done at the end of the
programming with respect to the amount of charge, is apparently enough
to indicate the proper logical level. Moreover, when the cell is exposed
to high temperature the charge leaks out but the manufacturer‘s
guarantee that the memory storage will withstand the JEDS218 standard,
this mean that this amount of charge should be enough for 10 years at
temperature ambient range of 25÷55°C. Hence, after 10 years, in the
worst-case scenario, the amount of charge might be so low that its
results can adversely affect its logical level.
In our previous work, we found that the programed cell array affected by
temperature as shown in figure 1, begin with the average voltage is
equal to Vt1 and later, when the leakage occurs, the
average voltage decreases while the variation increases.