Non-volatile storage system with resistance sensing and compensation

• US 7,616,498 B2
• Filed: 12/29/2006
• Issued: 11/10/2009
• Est. Priority Date: 12/29/2006
• Status: Expired due to Fees

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Cernea, Raul-Adrian, Mokhlesi, Nima
• Primary Examiner(s): Pham; Ly D
• Application Number:
  US11/617,981
• Publication Number:
  US 20080158983A1
• Time in Patent Office: 1,047 Days
• Field of Search: 365/185.17, 365/185.21
• US Class Current: 365/185.21
• CPC Class Codes: G11C 16/3418 Disturbance prevention or evaluation; Refreshing of disturbed memory data

Abstract

When reading data from a non-volatile storage element that is part of a group of connected non-volatile storage elements, resistance information is measured for the group. One or more read parameters are set based on the measured resistance information. The read process is then performed using the one or more parameters.

Claims

1. A non-volatile storage system, comprising:

a plurality of groups of connected non-volatile storage elements; and

one or more managing circuits in communication with said plurality of groups of connected non-volatile storage elements, said one or more managing circuits measure resistance information for each group as a whole, said one or more managing circuits read data from said groups of connected non-volatile storage elements in response to and using said resistance information.

2. A non-volatile storage system, comprising:

a plurality of groups of connected non-volatile storage elements; and

one or more managing circuits in communication with said plurality of groups of connected non-volatile storage elements, said one or more managing circuits measure resistance information for said plurality of groups of connected non-volatile storage elements, said one or more managing circuits read data from said groups of connected non-volatile storage elements in response to and using said resistance information,

wherein said one or more managing circuits classify each group as pertaining to a high resistance state or a low resistance state; and

said one or more managing circuits read data from groups using a read parameter chosen separately for each group by said one or more managing circuits based on whether a respective group has been classified as pertaining to a high resistance state or a low resistance state.

3. A non-volatile storage system according to claim 2, wherein:

said one or more managing circuits read data from said groups using bit line voltages chosen separately for each group by said one or more managing circuits based on said resistance information.

4. A non-volatile storage system according to claim 2, wherein:

said one or more managing circuits read data from said groups using word line voltages chosen separately for each group by said one or more managing circuits based on said resistance information.

5. A non-volatile storage system according to claim 2, wherein:

said one or more managing circuits read data from said groups using time periods for sensing that are chosen separately for each group by said one or more managing circuits based on said resistance information.

6. A non-volatile storage system according to claim 2, wherein:

said one or more managing circuits include sense amplifiers for each group; and

said one or more managing circuits read data from said groups using reference values chosen separately for each sense amplifier by said one or more managing circuits based on said resistance information.

7. A non-volatile storage system according to claim 2, wherein:

each group of connected non-volatile storage elements includes a target non-volatile storage element in each group;

each group of connected non-volatile storage elements includes a neighbor non-volatile storage element next to said target non-volatile storage element;

said one or more managing circuits provide compensation to said neighbor non-volatile storage elements while reading data from said target non-volatile storage elements.

8. A non-volatile storage system according to claim 7, wherein:

said one or more managing circuits determine condition information for said neighbor storage elements; and

said compensation is based on said condition information and said resistance information.

9. A non-volatile storage system according to claim 2, wherein:

said one or more managing circuits include any one or a combination of control circuitry, power circuitry, state machine circuitry, decoders, read/write circuits, processors, sense amplifiers and a controller.

10. A non-volatile storage system according to claim 2, wherein:

said groups of connected non-volatile storage elements are NAND strings.

11. A non-volatile storage system according to claim 10, wherein:

said one or more managing circuits measuring resistance information by applying a first voltage to a first subset of non-volatile storage elements of said groups, applying a second voltage to a second subset of said groups of non-volatile storage elements and sensing currents in said groups.

12. A non-volatile storage system according to claim 10, wherein:

said groups of connected non-volatile storage elements stores multiple bits of data in each non-volatile storage element.

13. A non-volatile storage system, comprising:

a NAND string, said NAND string includes a plurality of non-volatile storage elements; and

one or more managing circuits in communication with said NAND string, said one or more managing circuits measure resistance information for said NAND string and choose a parameter based on said resistance information, said one or more managing circuits perform one or more read operations on a target non-volatile storage element of said NAND string using said parameter.

14. A non-volatile storage system according to claim 13, wherein:

said parameter is a bit line voltage.

15. A non-volatile storage system according to claim 13, wherein:

said parameter is a control gate voltage.

16. A non-volatile storage system according to claim 13, wherein:

said one or more managing circuits include a sense amplifier in communication with said NAND string; and

said parameter is a reference value for said sense amplifier.

17. A non-volatile storage system according to claim 13, wherein:

said parameter is a compensation; and

said one or more managing circuits provide said compensation to a neighbor non-volatile storage element while performing read operations on said one of said non-volatile storage elements, said neighbor non-volatile storage element is next to said one of said non-volatile storage elements.

18. A non-volatile storage system according to claim 13, wherein:

said one or more managing circuits apply a first bit line voltage when measuring resistance information and a higher bit line voltage when performing said one or more read operations.

19. A non-volatile storage system according to claim 13, wherein:

said one or more managing circuits use a first integration time when measuring resistance information and a longer integration time when performing said one or more read operations.

20. A non-volatile storage system, comprising:

a plurality of groups of connected non-volatile storage elements, each group being a NAND string, and

one or more managing circuits in communication with said plurality of NAND strings, said one or more managing circuits measure resistance information for each NAND string, said one or more managing circuits read data from each NAND string using said resistance information.