Reducing program disturb in non-volatile storage

• US 8,189,378 B2
• Filed: 09/27/2006
• Issued: 05/29/2012
• 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): Hoang, Huan
• Assistant Examiner(s): RADKE, JAY W
• Application Number:
  US11/535,628
• Publication Number:
  US 20080084747A1
• Time in Patent Office: 2,071 Days
• Field of Search: 365/185.17, 365/185.18, 365/185.33
• 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
• CPC Class Codes: G11C 7/1006 Data managing, e.g. manipulating data before writing or reading out, data bus switches or control circuits therefor

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 method performed during programming of non-volatile storage, comprising:

boosting a group of connected non-volatile storage elements, the group of connected non-volatile storage elements includes a particular non-volatile storage element, the boosting includes;

applying a first boosting signal to one or more non-volatile storage elements of the group that have started but not completed full programming since a last erase process for the group, the one or more non-volatile storage elements include a first neighbor non-volatile storage element, the first neighbor non-volatile storage element is next to and on a first side of the particular non-volatile storage element, and

applying a second boosting signal to a plurality of other non-volatile storage elements of the group that have or not started programming since the last erase process for the group, the first boosting signal is greater in voltage 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; and

applying a program signal to the particular non-volatile storage element while the group is boosted such that the particular non-volatile storage element is not programmed in response to the program signal.

2. The method of claim 1, wherein

the boosting of the group of connected non-volatile storage elements includes 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 method 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 method of claim 1, wherein

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

5. The method of claim 1, wherein

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

6. A method performed during programming of non-volatile storage, comprising:

boosting a group of non-volatile storage elements, the group of non-volatile storage elements includes a particular non-volatile storage element, the boosting includes;

applying one or more boosting signals to one or more non-volatile storage elements of the group that have started but not completed full programming since a last erase process for the group, the one or more non-volatile storage elements include a first neighbor non-volatile storage element, the first neighbor non-volatile storage element is next to and on a first side of the particular non-volatile storage element, and

applying one or more different boosting signals to a plurality of non-volatile storage elements of the group that have not started programming since the last erase process for the group, the one or more boosting signals are 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 programmed state of the first neighbor non-volatile storage element; and

applying a program signal to the particular non-volatile storage element of the group while the group is boosted such that the particular non-volatile storage element is not programmed in response to the program signal.

7. The method of claim 6, wherein

the non-volatile storage elements of the group that have 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 a second non-volatile storage element next to the first non-volatile storage element.

8. The method of claim 6, wherein

the non-volatile storage elements of the group that have 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 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 method of claim 6, wherein

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

14. The method of claim 6, wherein

the one or more non-volatile storage elements of the group and the plurality of one or more non-volatile storage elements of the group are on the same side of the particular non-volatile storage element of the group.

10. A method performed during programming of non-volatile storage, the non-volatile storage includes a plurality of non-volatile storage elements, the method comprising:

partially programming non-volatile storage elements connected to a first control line of a plurality of control lines, the non-volatile storage elements connected to the first control line are part of the plurality of non-volatile storage elements;

partially programming non-volatile storage elements connected to a second control line of the plurality of control lines after partially programming non-volatile storage elements connected to the first control line, the non-volatile storage elements connected to the second control line are part of the plurality of non-volatile storage elements; and

completing programming of non-volatile storage elements connected to the first control line after partially programming non-volatile storage elements connected to the second control line, the completing programming comprises

applying a first boosting signal to the second control line,

applying one or more different boosting signals to a plurality of 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 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 programmed state associated with the non-volatile storage elements connected to the second control line, and

applying a program signal to the first control line 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.

11. The method of claim 10, wherein

the control lines that are connected to non-volatile storage elements that have completed programming since the last erase process for the plurality of non-volatile storage elements include a third control line that is next to the first control line;

and

the second control line is next to the first control line and on a different side of the first control line than the third control line.

12. The method of claim 10, wherein

the plurality of control lines are word lines.

13. The method of claim 10, wherein

the applying 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.

15. The method of claim 10, wherein

the second control line is next to the first control line and on a first side of the first control line;

and

the other control lines that have not yet received a programming signal since the last erase process for the plurality of non-volatile storage elements includes control lines on the first side of the first control line.

16. The method of claim 11, wherein

the other control lines that have not yet received a programming signal since the last erase process for the plurality of non-volatile storage elements includes control lines on the same side of the first control line as the second control line.