Static information storage and retrieval – Floating gate – Particular biasing
Reexamination Certificate
2006-03-23
2008-08-19
Phung, Anh (Department: 2824)
Static information storage and retrieval
Floating gate
Particular biasing
C365S185150
Reexamination Certificate
active
07414894
ABSTRACT:
A number of methods for identifying cells with poor subthreshold slope and reduced transconductance. A first set of techniques focuses on the poor subthreshold behavior of degraded storage elements by cycling cells and then programming them to a state above the ground state and the reading them with a control gate voltage below the threshold voltage of this state to see if they still conduct. A second set of embodiments focuses on weak transconductance behavior by reading programmed cells with a control gate voltage well above the threshold voltage. A third set of embodiments alters the voltage levels at the source-drain regions of the storage elements. The current-voltage curve of a good storage element is relatively stable under this shift in bias conditions, while degraded elements exhibit a larger shift. The amount of shift can be used to differentiate the good elements from the bad.
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Chen Jian
Kanebako Kazunori
Li Yan
Lutze Jeffrey W.
Tanaka Tomoharu
Davis , Wright, Tremaine, LLP
Phung Anh
SanDisk Corporation
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