Nonvolatile semiconductor memory device
AssigneeKabushiki Kaisha Toshiba
InventorsYasuhiro Shimura, Takuya Futatsuyama
Life of this patent
Estimating the term…
Abstract
A nonvolatile semiconductor memory device comprises a memory cell array including a plurality of memory cells, and a control circuit for the memory cell array. The control circuit is configured to perform a pre-read operation to read pre-selected memory cells before a read operation on target memory cells is performed and to change a read voltage to be applied to the target memory cells during the read operation based on a result of the pre-read operation.
Claims20
A nonvolatile semiconductor memory device comprising:
- a memory cell array including a plurality of memory cells;
- and
- a control circuit for the memory cell array,
- wherein the control circuit is configured to perform a pre-read operation to read pre-selected memory cells before a read operation on target memory cells is performed and to change a read voltage to be applied to the target memory cells during the read operation based on a result of the pre-read operation, and
- wherein the pre-selected memory cells include none or less than all of the target memory cells.
A nonvolatile semiconductor memory device comprising:
- a memory cell array including a plurality of memory cells, each of the memory cells having a semiconductor layer;
- and
- a control circuit for the memory cell array,
- wherein the control circuit is configured to perform a pre-read operation to read pre-selected memory cells before a first read operation on a first group of target memory cells is performed and a second read operation on a second group of target memory cells is performed, and to change a read voltage to be applied to the first group of memory cells during the first read operation and the second group of memory cells during the second read operation, based on a result of the pre-read operation and diameters of the semiconductor layers of the first and second groups of memory cells.
A method of controlling a nonvolatile semiconductor memory device having a memory cell array that includes a plurality of memory cells, the method comprising:
- performing a pre-read operation to read pre-selected memory cells before a read operation on target memory cells;
- changing a read voltage that is to be applied to the target memory cells during the read operation based on a result of the pre-read operation;
- and
- performing the read operation on the target memory cells;
- wherein the pre-selected memory cells include none or less than all of the target memory cells.
Dependencies are inferred from the claim text.