Programming method for flash memory capable of compensating reduction of read margin between states due to hot temperature stress
First Claim
1. A programming method for a flash memory device having a plurality of memory cells storing multi-bit data indicating one of a plurality of states, the programming method comprising:
- programming memory cells selected to have one of the plurality of states using multi-bit data;
detecting programmed memory cells within a predetermined region of a threshold voltage distribution, wherein the programmed memory cells have one of the plurality of states,wherein the predetermined region is selected by one of a first verify voltage and a read voltage and a second voltage, the first verify voltage being lower than the second verify voltage and higher than the read voltage; and
programming the detected memory cells to have a threshold voltage being equivalent to or higher than the second verify voltage corresponding to the respective states.
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Abstract
A program method of a flash memory device including a plurality of memory cells for storing multi-bit data indicating one of states. The program method includes programming memory cells selected to have one of the states by using multi-bit data; detecting programmed memory cells within a predetermined region of a threshold voltage distribution where the programmed memory cells having the respective states are distributed, wherein the predetermined region of the respective states is selected by one of a first verify voltage and a read voltage and a second voltage, the first verify voltage being lower than the second verify voltage and higher than the read voltage; and programming the detected memory cells to have a threshold voltage being equivalent to or higher than the second verify voltage corresponding to each of the states.
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Citations
17 Claims
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1. A programming method for a flash memory device having a plurality of memory cells storing multi-bit data indicating one of a plurality of states, the programming method comprising:
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programming memory cells selected to have one of the plurality of states using multi-bit data; detecting programmed memory cells within a predetermined region of a threshold voltage distribution, wherein the programmed memory cells have one of the plurality of states, wherein the predetermined region is selected by one of a first verify voltage and a read voltage and a second voltage, the first verify voltage being lower than the second verify voltage and higher than the read voltage; and programming the detected memory cells to have a threshold voltage being equivalent to or higher than the second verify voltage corresponding to the respective states. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A programming method for a flash memory device having a plurality of memory cells storing multi-bit data indicating one of first through fourth states, the programming method comprising:
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programming memory cells selected to have one of the states using multi-bit data; detecting programmed memory cells within a predetermined region of a threshold voltage distribution where the programmed memory cells having one of the first through fourth states are distributed, wherein the predetermined region is selected by one of a first verify voltage and a read voltage and a second voltage, the first verify voltage being lower than the second verify voltage and higher than the read voltage; and programming the detected memory cells to have a threshold voltage being equivalent to or higher than the second verify voltage corresponding to each of the states. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification