Apparatus with reduced program disturb in non-volatile storage

• US 8,184,478 B2
• Filed: 09/27/2006
• Issued: 05/22/2012
• Est. Priority Date: 09/27/2006
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: Hemink, Gerrit Jan, Lee, Shih-Chung
• Primary Examiner(s): Ho, Hoai V
• Assistant Examiner(s): RADKE, JAY W
• Application Number:
  US11/535,634
• Publication Number:
  US 20080084748A1
• Time in Patent Office: 2,064 Days
• Field of Search: 365/185.17, 365/185.18, 365/185.33, 365/185.02
• US Class Current: 365/185.02
• CPC Class Codes: G11C 11/5628 Programming or writing circuits; Data input circuits
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 16/12 Programming voltage switching circuits
• CPC Class Codes: G11C 16/3418 Disturbance prevention or evaluation; Refreshing of disturbed memory data
• CPC Class Codes: G11C 16/3427 Circuits or methods to prevent or reduce disturbance of the state of a memory cell when neighbouring cells are read or written
• CPC Class Codes: G11C 2211/5621 Multilevel programming verification

Abstract

A non-volatile semiconductor storage system is programmed in a manner that reduces program disturb by applying a higher boosting voltage on one or more word lines that are connected to non-volatile storage elements that may be partially programmed.

Claims

1. A non-volatile storage system, comprising:

a group of connected non-volatile storage elements including a particular non-volatile storage element and a first neighbor non-volatile storage element on a first side of the particular non-volatile storage element;

a set of word lines connected to the group of connected non-volatile storage elements; and

a managing circuit that includes one or more voltage providing circuits in communication with the set of word lines to provide signals to the group of connected non-volatile storage elements, the managing circuit boosts the group of connected non-volatile storage elements by applying a first boosting signal to the first neighbor non-volatile storage element of the group which has started but not completed full programming since a last erase process for the group and applying a second boosting signal to a plurality of other non-volatile storage elements of the group that have not started programming since the last erase process for the group, the first boosting signal is greater than the second boosting signal by at least a voltage offset based on the difference between an erased state and an intermediate programmed state of the first neighbor non-volatile storage element, the managing circuit applies a program signal to the particular non-volatile storage element of the group while the group is boosted in response to the first boosting signal and the second boosting signal such that the particular non-volatile storage element is not programmed in response to the program signal.

2. The non-volatile storage system of claim 1, wherein

the managing circuit'"'"'s boosting of the group of connected non-volatile storage elements includes the managing circuit applying the first boosting signal to an additional non-volatile storage element of the group which has started but not completed full programming since the last erase process for the group, the additional non-volatile storage element is next to the first neighbor non-volatile storage element.

3. The non-volatile storage system of claim 1, wherein

the first neighbor non-volatile storage element is on a drain side of the particular non-volatile storage element.

4. The non-volatile storage system of claim 3, wherein

the group of connected non-volatile storage elements comprises a NAND string.

5. The non-volatile storage system of claim 1, wherein

the group of connected non-volatile storage elements comprises multi-state non-volatile storage devices.

6. A non-volatile storage system, comprising:

a group of connected non-volatile storage elements;

a set of control lines connected to the group of connected non-volatile storage elements; and

a managing circuit that includes one or more voltage providing circuits in communication with the set of control lines to provide signals to the group of connected non-volatile storage elements, the managing circuit boosts the group of connected non-volatile storage elements by applying a first boosting signal to one or more non-volatile storage elements of the group that has started but not completed full programming since a last erase process for the group and applying a second set of one or more boosting signals to a plurality of non-volatile storage elements of the group that have completed full programming or not started programming since the last erase process for the group, the first boosting signal is greater than the second set of one or more boosting signals by at least a voltage offset based on the difference between an erased state and an intermediate programmed state of the one or more non-volatile storage elements, the managing circuit applies a program signal to a particular non-volatile storage element of the group while the group is boosted in response to the first boosting signal and the second set of one or more boosting signals such that the particular non-volatile storage element is not programmed in response to the program signal, at least one of the one or more non-volatile storage elements of the group that has started but not completed full programming and at least one of the plurality of non-volatile storage elements of the group that have not started programming are on a same side of the particular non-volatile storage element.

7. The non-volatile storage system of claim 6, wherein

the one or more non-volatile storage elements of the group that has started but not completed full programming since the last erase process for the group includes a first non-volatile storage element next to and on a first side of the particular non-volatile storage element and a second non-volatile storage element next to the first non-volatile storage element.

8. The non-volatile storage system of claim 6, wherein

the one or more non-volatile storage elements of the group that has started but not completed full programming since the last erase process for the group includes a first non-volatile storage element next to and on a first side of the particular non-volatile storage element and a second non-volatile storage element next to the first non-volatile storage element, the first side is associated with a drain side of the particular non-volatile storage element.

9. The non-volatile storage system of claim 6, wherein

the one or more non-volatile storage elements of the group that has started but not completed full programming since the last erase process for the group includes a first non-volatile storage element next to and on a first side of the particular non-volatile storage element;

and

the plurality of non-volatile storage elements of the group that have not started programming includes all non-volatile storage elements of the group that have not started programming since the last erase process for the group.

10. The non-volatile storage system of claim 6, wherein

the managing circuit'"'"'s application of the second set of one or more boosting signals to non-volatile storage elements of the group that have not started programming since the last erase process for the group includes applying an isolation signal to a different non-volatile storage element and a pass signal to the remaining non-volatile storage elements of the group that have not started programming since the last erase process for the group.

11. The non-volatile storage system of claim 6, wherein

the one or more non-volatile storage elements of the group that has started but not completed full programming since the last erase process for the group include a first non-volatile storage element next to and on a first side of the particular non-volatile storage element;

and

the managing circuit'"'"'s application of the second set of one or more boosting signals to non-volatile storage elements of the group that have not started programming since the last erase process for the group includes applying an isolation signal to a different non-volatile storage element and a pass signal to other non-volatile storage elements of the group that have not started programming since the last erase process for the group.

12. The non-volatile storage system of claim 6, wherein

the group of connected non-volatile storage elements comprises a NAND string.

13. The non-volatile storage system of claim 6, wherein

the group of connected non-volatile storage elements comprises multi-state non-volatile storage devices.

14. A non-volatile storage system, comprising:

a plurality of non-volatile storage elements;

a set of control lines connected to the plurality of non-volatile storage elements, the set of control lines includes a first control line and a second control line next to the first control line, the set of control lines includes a third control line on a same side of the first control line as the second control line, each control line is connected to multiple sets of connected non-volatile storage elements of the plurality; and

a managing circuit that includes one or more voltage providing circuits in communication with the set of control lines to provide signals to the plurality of non-volatile storage elements, the managing circuit partially programs non-volatile storage elements connected to the first control line, the managing circuit partially programs non-volatile storage elements connected to the second control line after partially programming non-volatile storage elements connected to the first control line, the managing circuit completes programming of the non-volatile storage elements connected to the first control line after partially programming the non-volatile storage elements connected to the second control line and prior to starting programming of non-volatile storage elements connected to the third control line, the managing circuit completes the programming of non-volatile storage elements connected to the first control line by applying a first boosting signal to the second control line and applying one or more different boosting signals to all other control lines that have not yet received a programming signal since the last erase process for the plurality of non-volatile storage elements, the all other control lines that have not yet received a programming signal since the last erase process for the plurality of non-volatile storage elements include the third control line, the first boosting signal is higher in voltage than the one or more different boosting signals by at least a voltage offset based on the difference between an erased state and an intermediate state associated with the non-volatile storage elements connected to the second control line, the managing circuit applies a program signal to the first control line while boosting in response to the first boosting signal and the one or more different boosting signals in order to complete the programming of appropriate non-volatile storage elements connected to the first control line without disturbing non-volatile storage elements connected to the first control line that are not supposed to be programmed.

15. The non-volatile storage system of claim 14, wherein

the set of control lines are word lines.

16. The non-volatile storage system of claim 14, wherein

the managing circuit'"'"'s application of one or more different boosting signals includes applying a common signal to all control lines that have not yet received a programming signal since the last erase process for the plurality of non-volatile storage elements;

and

the common signal is lower in voltage than the first boosting signal.

17. The non-volatile storage system of claim 14, wherein

the managing circuit'"'"'s application of one or more different boosting signals includes applying an isolation signal to a different control line and a pass signal to other control lines.

18. The non-volatile storage system of claim 14, wherein

the non-volatile storage elements comprise multiple NAND strings.

19. The non-volatile storage system of claim 14, wherein

the non-volatile storage elements comprise multi-state non-volatile storage devices.

20. The non-volatile storage system of claim 14, wherein

the third control line is next to the second control line.