Boosting channels of memory cells to reduce program disturb
View Patent ↗A method for programming a non-volatile memory device includes concurrently boosting channels of memory cells in a selected memory string and an unselected memory string of the memory device, discharging the boosted channels of the memory cells in the selected memory string, and programming a selected memory cell in the selected memory string after discharging the boosted channels in the selected memory string.
1. A method for programming a non-volatile memory device, comprising:
concurrently boosting channels of a first set of memory cells in a selected memory string and a second set of memory cells in an unselected memory string of the memory device, wherein boosting channels of the first set of memory cells in the selected memory string and the second set of memory cells in the unselected memory string comprises applying a first bias voltage to a control gate of a first select transistor in the selected memory string and to a control gate of a second select transistor in the unselected memory string, wherein the first bias voltage maintains the first and second select transistors in an off state;
discharging the boosted channels of the first set of memory cells in the selected memory string; and
programming a selected memory cell in the first set of memory cells in the selected memory string after discharging the boosted channels of the first set of memory cells in the selected memory string.
2. The method of claim 1 , wherein boosting channels of the first set of memory cells in the selected memory string and the second set of memory cells in the unselected memory string further comprises:
applying a pass voltage to access lines of the first set of memory cells in the selected memory string and the second set of memory cells in the unselected memory string while the first and second select transistors are in the off state.
3. The method of claim 2 , wherein discharging the boosted channels comprises:
applying a second bias voltage to the control gates of the first select transistor in the selected memory string and the second select transistor in the unselected memory string, wherein the second bias voltage causes the first select transistor in the selected memory string to enter an on state to discharge the boosted channels in the selected memory string.
4. The method of claim 3 , wherein the second bias voltage maintains the second select transistor in the unselected memory string in the off state to maintain the boosted channels in the unselected memory string.
5. The method of claim 4 , wherein the first and second select transistors are select gate drain (SGD) transistors.
6. The method of claim 1 , wherein programming the selected memory cell comprises:
applying a program enable voltage to a first data line of the selected memory string; and
applying a programming voltage to an access line of the selected memory cell to increase a threshold voltage of the selected memory cell while the first data line is at the program enable voltage.
7. The method of claim 6 , wherein programming the selected memory cell further comprises:
applying a program inhibit voltage to a second data line of the unselected memory string while the programming voltage is applied to the access line.
8. A method for programming a non-volatile memory device, comprising:
concurrently boosting channels of a first set of memory cells in a selected memory string and a second set of memory cells in an unselected memory string of the memory device by isolating the selected memory string and the unselected memory string from respective data lines and a source, and applying a pass voltage to access lines of the first set of memory cells in the selected memory string and the second set of memory cells in the unselected memory string while the selected memory string and the unselected memory string are isolated from their respective data lines and the source, wherein boosting channels of the first set of memory cells in the selected memory string and the second set of memory cells in the unselected memory string comprises maintaining a first select transistor in the selected memory string and a second select transistor in the unselected memory string in an off state while applying the pass voltage;
discharging the boosted channels of the first set of memory cells in the selected memory string; and
programming a selected memory cell in the first set of memory cells in the selected memory string after discharging the boosted channels of the first set of memory cells in the selected memory string.
9. The method of claim 8 , wherein discharging the boosted channels comprises:
biasing the first select transistor in the selected memory string and the second select transistor in the unselected memory string to cause the first select transistor in the selected memory string to enter an on state and maintain the second select transistor in the unselected memory string in the off state.
10. The method of claim 9 , wherein the biasing drives the boosted channels of the first set of memory cells in the selected memory string to ground while maintaining the boosted channels of the second set of memory cells in the unselected memory string.
11. The method of claim 8 , wherein programming the selected memory cell comprises:
enabling for programming a first data line of the selected memory string;
inhibiting for programming a second data line of the unselected memory string; and
applying a program voltage to an access line of the selected memory cell.
12. A method for programming a non-volatile memory device, comprising:
concurrently boosting channels of a first set of memory cells in a selected memory string and a second set of memory cells in an unselected memory string of the memory device, wherein boosting channels of the first set of memory cells in the selected memory string and the second set of memory cells in the unselected memory string comprises biasing a first select gate drain (SGD) transistor in the selected memory string and a second SGD transistor in the unselected memory string to maintain the first and second SGD transistors in an off state;
discharging the boosted channels of the first set of memory cells in the selected memory string and maintaining the boosted channels of the second set of memory cells in the unselected memory string; and
programming a selected memory cell in the first set of memory cells in the selected memory string after discharging the boosted channels of the first set of memory cells in the selected memory string and while maintaining the boosted channels of the second set of memory cells in the unselected memory string.
13. The method of claim 12 , wherein boosting channels of the first set of memory cells in the selected memory string and the second set of memory cells in the unselected memory string further comprises:
applying a pass voltage to access lines of the first set of memory cells in the selected memory string and the second set of memory cells in the unselected memory string while the first and second SGD transistors are in the off state.
14. The method of claim 13 , wherein discharging the boosted channels comprises:
biasing the first SGD transistor in the selected memory string and the second SGD transistor in the unselected memory string to drive the boosted channels of the first set of memory cells in the selected memory string to ground.
15. The method of claim 12 , wherein the non-volatile memory device is a NAND architecture memory device.
16. The method of claim 12 , wherein the non-volatile memory device is a three-dimensional (3D) NAND architecture memory device.