Non-Volatile Storage With Temperature Compensation Based On Neighbor State Information

• US 20110205823A1
• Filed: 02/19/2010
• Published: 08/25/2011
• Est. Priority Date: 02/19/2010
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: Sato, Shinji, Hemink, Gerrit Jan
• Granted Patent: US 8,213,255 B2
• Time in Patent Office: Days
• US Class Current: 365/211
• CPC Class Codes: G11C 11/5642 Sensing or reading circuits; Data output circuits
• CPC Class Codes: G11C 16/26 Sensing or reading circuits; Data output circuits
• CPC Class Codes: G11C 7/04 with means for avoiding disturbances due to temperature effects

Abstract

Data is programmed into and read from a set of target memory cells. When reading the data, temperature compensation is provided. The temperature compensation is based on temperature information and the state of one or more neighbor memory cells. In one embodiment, when data is read from set of target memory cells, the system senses the current temperature and determines the differences in temperature between the current temperature and the temperature at the time the data was programmed. If the difference in temperature is greater than a threshold, then the process of reading the data includes providing temperature compensation based on temperature information and neighbor state information. In one alternative, the decision to provide the temperature compensation can be triggered by conditions other than a temperature differential.

Claims

1. A method for operating non-volatile storage, comprising:

programming data into a set of non-volatile storage elements; and

reading the data from the set of non-volatile storage elements after the programming, the reading of the data includes providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element.

2. The method of claim 1, wherein the reading the data includes:

determining that a current temperature differs from a temperature at a time of programming the data by at least a threshold, the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element is performed in response to determining that the current temperature differs from the temperature at the time of programming the data by at least the threshold.

3. The method of claim 1, wherein the reading the data includes:

determining that a temperature differential is greater than a threshold, the temperature differential is a difference between a current temperature and a temperature at a time of programming the data, the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element includes providing compensation based on state information for at least one neighbor non-volatile storage element and the temperature differential in response to determining that the temperature differential is greater than the threshold.

4. The method of claim 1, wherein the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element comprises:

determining an initial compensation value based on temperature; and

adjusting the initial compensation value based on the state information for at least one neighbor non-volatile storage element.

5. The method of claim 1, wherein the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element comprises:

determining a compensation value based on temperature and state information for at least one neighbor non-volatile storage element.

6. The method of claim 1, wherein the reading data includes:

applying the temperature compensation; and

sensing information from the set of non-volatile storage elements after and based on the applying the temperature compensation.

7. The method of claim 1, wherein the reading data includes:

sensing information from the set of non-volatile storage elements;

applying the temperature compensation after the sensing; and

determining the data based on the sensing and the applying.

8. The method of claim 1, wherein the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element comprises:

adjusting read compare levels for the reading of the data, the read compare levels are adjusted based on temperature information and state information for at least one neighbor non-volatile storage element.

9. The method of claim 1, wherein the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element comprises:

adjusting an error correction code decoding process based on temperature information and state information for at least one neighbor non-volatile storage element.

10. The method of claim 1, wherein the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element comprises:

adjusting a LRR table for an error correction code decoding process based on temperature information and state information for at least one neighbor non-volatile storage element.

11. The method of claim 1, wherein:

the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element is performed by a controller that is implemented on a separate integrated circuit than the set of non-volatile storage elements.

12. The method of claim 1, wherein:

the providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element is performed on an integrated circuit that includes the set of non-volatile storage elements.

13. The method of claim 1, wherein the reading comprises:

determining current temperature information;

accessing temperature information from programming the data;

determining a temperature differential between the current temperature information and the temperature information from programming the data;

determining state information for one or more neighbor non-volatile storage elements, with respect to one or more target non-volatile storage elements;

determining that the temperature differential is greater than a threshold;

applying temperature compensation for one or more target non-volatile storage element based on the temperature differential and the state information for appropriate neighbor non-volatile storage elements in response to determining that the temperature differential is greater than the threshold;

sensing information from target non-volatile storage elements; and

reporting data based on the sensing and the temperature compensation.

14. The method of claim 1, wherein the reading comprises:

determining current temperature information;

accessing temperature information from programming the data;

determining a temperature differential between the current temperature information and the temperature information from programming the data;

adjusting the read parameters based on the received current temperature information;

sensing initial information from the set of non-volatile storage elements using the read operation parameters;

identifying data stored in the set of non-volatile storage elements from the initial information using temperature compensation that is based on the temperature differential and information representing states of one or more neighbors for the set of non-volatile storage elements; and

reporting the identified data.

15. The method of claim 1, wherein the reading comprises:

performing read operations at multiple compare values for each data state; and

determining a probability for each bit of the data based on the read operations, temperature information and state information for at least one neighbor non-volatile storage element.

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

the data recovery process includes the controller performing read operations at multiple compare values for each data state and determining a probability for each bit of the data stored in the plurality of non-volatile storage elements based on the state information for at least one neighbor non-volatile storage element and the temperature differential.

16. A method for operating non-volatile storage, comprising:

determining current temperature information;

accessing temperature information from programming data into a target non-volatile storage element;

determining a temperature differential between the current temperature information and the temperature information from programming data;

determining state information for one or more neighbor non-volatile storage elements of the target non-volatile storage element;

determining and applying an amount of temperature compensation for the target non-volatile storage element based on the state information for the one or more neighbor non-volatile storage elements and temperature data if the temperature differential is greater than a threshold;

sensing information from the target non-volatile storage element; and

reporting data based on the sensing and the applied temperature compensation.

17. The method of claim 16, wherein:

the temperature compensation is applied to the sensing.

18. The method of claim 16, wherein:

the temperature compensation is applied subsequent to the sensing.

19. The method of claim 16, wherein the applying an amount of temperature compensation for the target non-volatile storage element comprises:

adjusting an error correction decoding process by adjusting a probability of a data bit associated with the target non-volatile storage element based on the temperature differential and the state information for the one or more neighbor non-volatile storage elements.

20. A method for operating non-volatile storage, comprising:

receiving current temperature information for a set of non-volatile storage elements;

receiving programming temperature information for the set of non-volatile storage elements corresponding to a temperature during a previous programming of the set of non-volatile storage elements;

adjusting one or more operation parameters based on at least the current temperature information;

sensing initial information from the set of non-volatile storage elements using the one or more operation parameters;

identifying data stored in the set of non-volatile storage elements from the initial information using temperature compensation that is based on information representing states of one or more neighbors for each of the set of non-volatile storage elements and a temperature differential between the current temperature information and the programming temperature information; and

reporting the identified data.

21. The method of claim 20, wherein:

the identifying data includes an error correction code decoding process that uses information representing states of one or more neighbors for each of the set of non-volatile storage elements and the temperature differential.

22. The method of claim 20, wherein the identifying data comprises:

performing read operations at multiple compare values for each data state; and

determining a probability for each bit of the data stored in the set of non-volatile storage elements based on the read operations, the temperature differential and the information representing states of one or more neighbors for each of the set of non-volatile storage elements.

23. A non-volatile storage system, comprising:

a set of non-volatile storage elements; and

one or more managing circuits in communication with the set of non-volatile storage elements, the one or more managing circuits read data from the set of non-volatile storage elements by providing temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element.

24. The non-volatile storage system of claim 23, wherein:

the one or more managing circuits determine that a temperature differential is greater than a threshold and provide the temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element in response to determining that the temperature differential is greater than the threshold, the temperature differential is a difference between a temperature at programming the data and a temperature at reading the data.

25. The non-volatile storage system of claim 24, wherein:

the temperature information is the temperature differential.

26. The non-volatile storage system of claim 23, wherein:

the one or more managing circuits provided temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element by adjusting read compare levels for the reading of the data based on temperature information and state information for at least one neighbor non-volatile storage element.

27. The non-volatile storage system of claim 23, comprises:

the one or more managing circuits provided temperature compensation based on temperature information and state information for at least one neighbor non-volatile storage element by adjusting an error correction code decoding process based on temperature information and state information for at least one neighbor non-volatile storage element.

28. The non-volatile storage system of claim 23, wherein:

the one or more managing circuits read data from the set of non-volatile storage elements by determining current temperature information, accessing temperature information from programming the data, determining a temperature differential between the current temperature information and the temperature information from programming the data, determining state information for one or more neighbor non-volatile storage elements, determining and applying temperature compensation for one or more target non-volatile storage element based on the temperature differential and the state information for appropriate neighbor non-volatile storage elements, sensing information from target non-volatile storage elements, and reporting data based on the sensing and the temperature compensation.

29. The non-volatile storage system of claim 23, wherein:

the one or more managing circuits read data from the set of non-volatile storage elements by determining current temperature information, accessing temperature information from programming the data, determining a temperature differential between the current temperature information and the temperature information from programming the data, adjusting the one or more operation parameters based on the received current temperature information, sensing initial information from the set of non-volatile storage elements using the one or more operation parameters, identifying data stored in the set of non-volatile storage elements from the initial information using temperature compensation that is based on the temperature differential and information representing states of one or more neighbors for the set of non-volatile storage elements, and reporting the identified data.

30. The non-volatile storage system of claim 23, wherein:

the one or more managing circuits read data from the set of non-volatile storage elements by performing read operations at multiple compare values for each data state and determining a probability for each bit of the data of representing a particular data value based on the read operations, temperature information and neighbor state information.

31. A non-volatile storage system, comprising:

a host interface;

a memory circuit including a plurality of non-volatile storage elements, decoders, a temperature sensor and a state machine; and

a controller circuit that is separate from and in communication with the memory circuit and the host interface, the controller circuit is in communication with the state machine, from the memory circuit the controller circuit receives current temperature information from the temperature sensor and temperature information from programming the non-volatile storage elements, from the memory circuit the controller receives initial information sensed from the non-volatile storage elements, the controller determines temperature compensation based on state information for at least one neighbor non-volatile storage element and a temperature differential between the current temperature information and the temperature information from programming the non-volatile storage elements, the controller performs a data recovery process using the initial information in combination with temperature compensation to identify user data stored in the non-volatile storage elements.

32. The non-volatile storage system of claim 31, wherein:

the data recovery process includes the controller performing an error correction code decoding process that uses the state information for at least one neighbor non-volatile storage element and the temperature differential.