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US 9,001,578 B2Granted
Soft erasure of memory cells
AssigneeSeagate Technology LLC
InventorsYoungPil Kim, Dadi Setiadi, Wei Tian, Antoine Khoueir, Rodney Virgil Bowman
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Abstract
Apparatus and method for managing data in a memory, such as but not limited to a flash memory array. In accordance with some embodiments, a soft erasure is performed on a block of memory cells by toggling an erasure status value without otherwise affecting a written state of the cells in the block. The memory cells are subsequently overwritten with a set of data using a write polarity direction determined responsive to the toggled erasure status value.
Claims20
A method comprising:
- performing a soft erasure of a block of memory cells by toggling an erasure status value without otherwise affecting a written state of the cells in the block;
- and
- subsequently overwriting a set of data to the block using a write polarity direction determined responsive to the toggled erasure status value.
An apparatus comprising:
- a block of memory cells;
- and
- a control circuit adapted to perform a soft erasure of the cells by toggling an erasure status value without otherwise affecting a written state of the cells, followed by overwriting a set of data to the block using a write polarity direction determined responsive to the toggled erasure status value.
An apparatus comprising:
- a flash memory array arranged into a plurality of garbage collection units (GCUs) each allocated as a unit;
- a hard erasure circuit adapted to perform a hard erasure on a selected GCU by removing accumulated charge from floating gate structures of flash memory cells in said GCU to return said cells to a baseline charge state;
- a soft erasure circuit adapted to perform a soft erasure on the selected GCU by toggling an erasure status value without otherwise affecting a written state of the cells therein;
- and
- a write circuit adapted to overwrite data to the cells in the selected GCU using a write polarity direction determined responsive to the toggled erasure status value.
2 more elements
Dependencies are inferred from the claim text.