Abstract
This study comprehensively investigates the effect of hydrogen content in forming gas annealing (FGA) on the endurance of NAND flash memories by statistically analyzing the transconductance (
G
m
,
m
a
x
) characteristics. The
G
m
,
m
a
x
degradation (
Δ
G
m
,
m
a
x
) worsened with higher cycling temperature, delayed time period from erasing to programming (
t
E
P
) operation, and higher word-line bias (
V
A
) during
t
E
P
.
Moreover, these effects become more pronounced as the hydrogen content in FGA increases. Using the measured
G
m
,
m
a
x
distributions and Monte -Carlo TCAD technology, the activation energy (
E
A
) of oxide damage creation can be extracted. The extracted
E
A
values were 50 meV and 160 meV for the diluted (4%) and pure (100%) hydrogen samples, respectively. This suggests that a higher hydrogen concentration results in more ionized hydrogen atoms remaining in the oxide layer. During
t
E
P
,
these hydrogen ions can drift near the Si/SiO2 surface, where they may react to form trap states.
E
A
is revealed to have a linear relationship with respect to
V
A
,
where the slope is independent of the hydrogen content in FGA.
Publisher
The Electrochemical Society