Method for erasing an NROM cell
AssigneeMicron Technology, Inc.
InventorsAndrei Mihnea, Chun Chen
Life of this patent
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Abstract
An operation to erase a nitride read only memory (NROM) memory block starts by erasing the memory block. An erase verify operation can then be performed to determine the success of the erase. If a read operation is performed and column current is detected, a high-efficiency recovery operation is performed. If the read operation is performed and column current is not detected, the erase operation has been successfully completed.
Claims20
A method for erasing a nitride read only memory (NROM) block comprising a plurality of short-channel memory cells each having a gate input and two source/drain regions, the method comprising:
- performing an erase operation on the memory block;
- verifying erasure of the memory block;
- and
- if erasure is not complete, performing a recovery operation on the plurality of memory cells such that a threshold voltage indicating a programmed state, for over-erased cells, is increased.
A method for erasing a nitride read only memory (NROM) block comprising a plurality of columns having a plurality of short-channel memory cells each having a gate connection and first and second source/drain regions, the method comprising:
- performing an erase operation on the NROM block;
- performing a verify read operation on the NROM block to detect column current in any of the plurality of columns of the NROM block;
- and
- if column current is detected, performing a recovery operation on the plurality of memory cells such that a threshold voltage indicating a programmed state, for over-erased cells, is increased.
A method for erasing a nitride read only memory (NROM) block comprising a plurality of columns having a plurality of short-channel memory cells each having a gate connection and first and second source/drain regions, the method comprising:
- performing an erase operation on the NROM block;
- determining if any threshold voltages of the memory cells of the NROM block are less than a first predetermined threshold to indicate over-erased cells;
- and
- if any of the threshold voltages are less than the predetermined threshold, performing a recovery operation on the plurality of memory cells to increase the threshold voltages to a second predetermined threshold for the over-erased cells.
Dependencies are inferred from the claim text.