NAND Flash Memory Device Having Dummy Memory cells and Methods of Operating Same
First Claim
1. A NAND flash memory device comprising:
- a plurality of memory cells connected in series;
at least one dummy memory cell connected in series with the plurality of memory cells;
a selection transistor connected in series with the dummy memory cell and the plurality of memory cells; and
a control circuit configured to apply, during a program operation, a first word line voltage to non-selected ones of the memory cells, a second word line voltage greater than the first word line voltage to a selected memory cell, and a third word line voltage lower than the first word line voltage to the dummy memory cell.
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Abstract
A NAND flash memory device includes a control circuit configured to apply, during a program operation, a first word line voltage to non-selected ones of a plurality of serially-connected memory cells, a second word line voltage greater than the first word line voltage to a selected one of the plurality of memory cells, and a third word line voltage lower than the first word line voltage to a dummy memory cell connected in series with the plurality of memory cells. In other embodiments, a control circuit is configured to program a dummy memory cell before and/or after each erase operation on a plurality of memory cells connected in series therewith. In still other embodiments, a control circuit is configured to forego erasure of a dummy memory cell while erasing a plurality of memory cells connected in series therewith.
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Citations
18 Claims
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1. A NAND flash memory device comprising:
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a plurality of memory cells connected in series;
at least one dummy memory cell connected in series with the plurality of memory cells;
a selection transistor connected in series with the dummy memory cell and the plurality of memory cells; and
a control circuit configured to apply, during a program operation, a first word line voltage to non-selected ones of the memory cells, a second word line voltage greater than the first word line voltage to a selected memory cell, and a third word line voltage lower than the first word line voltage to the dummy memory cell. - View Dependent Claims (2, 3, 4)
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5. A NAND flash memory device comprising:
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a plurality of memory cells connected in series;
at least one dummy memory cell connected in series with the plurality of memory cells;
a selection transistor connected in series with the dummy memory cell; and
a control circuit configured to program the dummy memory cell before and/or after erase operations on the plurality of memory cells and the dummy memory cell. - View Dependent Claims (6, 7, 8, 9)
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10. A NAND flash memory device comprising:
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a plurality of memory cells connected in series;
at least one dummy memory cell connected in series with the plurality of memory cells;
a selection transistor connected in series with the dummy memory cell; and
a control circuit configured not to erase the dummy memory cell while erasing the plurality of memory cells. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A NAND flash memory device comprising:
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a plurality of memory cells connected in series;
at least one dummy memory cell connected in series with the plurality of memory cells;
a selection transistor connected in series with the dummy memory cell; and
a control circuit configured to apply, during the erase verification operation, a first erase verify voltage to the memory cells, and a second erase verify voltage greater than the first verify voltage to the dummy memory cell. - View Dependent Claims (17, 18)
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Specification