Method for estimating and reporting the life expectancy of flash-disk memory

• US 7,512,847 B2
• Filed: 02/06/2007
• Issued: 03/31/2009
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: Western Digital Israel Limited (Western Digital Corporation)
• Original Assignee: SanDisk IL Ltd. (Western Digital Corporation)
• Inventors: Pomerantz, Itzhak, Bychkov, Eyal, Ziegler, Alon, Meir, Avraham
• Primary Examiner(s): Trimmings; John P
• Application Number:
  US11/702,500
• Publication Number:
  US 20070198786A1
• Time in Patent Office: 784 Days
• Field of Search: None
• US Class Current: 714/723
• CPC Class Codes: G11C 16/04 using variable threshold transistors, e.g. FAMOS
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles
• CPC Class Codes: G11C 2029/0409 Online test
• CPC Class Codes: G11C 2029/5002 Characteristic
• CPC Class Codes: G11C 29/42 using error correcting codes [ECC] or parity check
• CPC Class Codes: G11C 29/50 Marginal testing, e.g. race, voltage or current testing
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents

Abstract

A method for managing a memory device, a memory device so managed and a system that includes such a memory device. A value of a longevity parameter of the device is monitored after a data operation on the device in which the monitoring is performed by the device. A grade of the device is derived from the value. Preferred longevity parameters include a ratio of successfully-processed data to unsuccessfully-processed data and a deviation in a power consumption of the device. The grade serves as a forecast of a life expectancy of the memory. Preferred grades include: a comparison grade, a maximum grade, and an average grade.

Claims

1. A method for managing a memory device, the method comprising the steps of:

(a) monitoring a value of a longevity parameter of the memory device after a programming operation on the memory device, said monitoring being performed by the memory device; and

(b) deriving a grade of the memory device from said value;

wherein said value is a number of programming pulses, associated with said operation, required to change logic states of at least one cell in a page of the memory device.

2. The method of claim 1, wherein said longevity parameter is a ratio of successfully-processed data to unsuccessfully-processed data.

3. The method of claim 1, wherein said longevity parameter is a deviation in a power consumption of the memory device.

4. The method of claim 1, wherein said deviation is an average of measurements for a plurality of said operations.

5. The method of claim 1, wherein said grade serves as a forecast of a life expectancy of said memory.

6. The method of claim 1, wherein said operation is a programming operation, and wherein said value is a number of healthy cells in a page of the memory device.

7. The method of claim 1, wherein said operation is an erase operation, and wherein said value is a number of healthy cells in a block of the memory device.

8. The method of claim 1, wherein said operation is selected from the group consisting of:

writing data, reading data, and erasing data.

9. The method of claim 1, wherein said grade is selected from the group consisting of:

a comparison grade of a current said value to a pre-determined reference said value, a maximum grade of a plurality of said values stored in a monitoring device, and an average grade of said plurality of said values stored in said monitoring device.

10. The method of claim 1, wherein said grade is a comparison grade of a current value to a pre-determined reference value, the method further comprising the step of:

(c) storing said pre-determined reference value in the memory device upon manufacture of the memory device.

11. The method of claim 1, wherein said step of monitoring includes accessing the memory device for the purpose of deriving said grade.

12. The method of claim 1, the method further comprising the step of:

(c) storing said grade in a monitoring device.

13. The method of claim 12, wherein said monitoring device is selected from the group consisting of:

the memory device, an embedded controller of the memory device, and a host system of the memory device.

14. The method of claim 1, wherein said step of deriving is initiated by the memory device.

15. The method of claim 1, wherein said step of deriving is initiated by a host system of the memory device.

16. The method of claim 1, wherein said step of deriving is initiated by an embedded controller of the memory device.

17. The method of claim 1, wherein said step of deriving is initiated by an application running on a host system.

18. The method of claim 1, wherein said step of deriving is initiated by an operating system running on a host system.

19. A memory device for managing data, the device comprising:

(a) a memory; and

(b) a controller operative;

(i) to monitor a value of a longevity parameter after a programming operation on said memory; and

(ii) to derive a grade of the memory device from said value;

wherein said value is a number of programming pulses associated with said operation required to change logic states of at least one cell in a page of the memory device.

20. The memory device of claim 19, wherein said grade serves as a forecast of a life expectancy of the memory device.

21. A system for managing data, the system comprising:

(a) a memory device including a memory; and

(b) a processor, housed in said memory device, operative;

(i) to monitor a value of a longevity parameter after a programming operation on said memory; and

(ii) to derive a grade of said memory device from said value;

wherein said value is a number of programming pulses, associated with said operation, required to change logic states of at least one cell in a page of the memory device.

22. The system of claim 21, wherein said grade serves as a forecast of a life expectancy of said memory device.

23. A method for managing a memory device, the method comprising the steps of:

(a) monitoring a value of a longevity parameter of the memory device after an erase operation on the memory device, said monitoring being performed by the memory device; and

(b) deriving a grade of the memory device from said value;

wherein said value is a number of programming pulses, associated with said operation, required to change logic states of at least one cell in a block of the memory device.

24. A memory device for managing data, the device comprising:

(a) a memory; and

(b) a controller operative;

(i) to monitor a value of a longevity parameter after an erase operation on said memory; and

(ii) to derive a grade of the memory device from said value;

wherein said value is a number of programming pulses, associated with said operation, required to change logic states of at least one cell in a block of the memory device.

25. A system for managing data, the system comprising:

(a) a memory device including a memory; and

(b) a processor, housed in said memory device, operative;

(i) to monitor a value of a longevity parameter after an erase operation on said memory; and

(ii) to derive a grade of said memory device from said value;

wherein said value is a number of programming pulses, associated with said operation, required to change logic states of at least one cell in a block of the memory device.

26. A method for managing a memory device, the method comprising the steps of:

(a) monitoring a value of a deviation in a power consumption of the memory device after a data operation on the memory device, said monitoring being performed by the memory device; and

(b) deriving a grade of the memory device from said value.

27. The method of claim 26, wherein the memory device is a flash memory device.

28. A memory device for managing data, the device comprising:

(a) a memory; and

(b) a controller operative;

(i) to monitor a value of a deviation in a power consumption of the memory device after a data operation on said memory; and

(ii) to derive a grade of the memory device from said value.

29. The method of claim 28, wherein said memory is a flash memory.

30. A system for managing data, the system comprising:

(a) a memory device including a memory; and

(b) a processor, housed in said memory device, operative;

(i) to monitor a value of a deviation in a power consumption of the memory device after a data operation on said memory; and

(ii) to derive a grade of said memory device from said value.

31. The method of claim 30, wherein said memory device is a flash memory device.

32. A method for managing a memory device, the method comprising the steps of:

(a) monitoring a number of healthy cells in a block of the memory device after an erase operation on the memory device, said monitoring being performed by the memory device; and

(b) deriving a grade of the memory device from said value.

33. A memory device for managing data, the device comprising:

(a) a memory; and

(b) a controller operative;

(i) to monitor a number of healthy cells in a block of said memory after an erase operation on said memory; and

(ii) to derive a grade of the memory device from said value.

34. A system for managing data, the system comprising:

(a) a memory device including a memory; and

(b) a processor, housed in said memory device, operative;

(i) to monitor a number of healthy cells in a block of said memory after an erase operation on said memory; and

(ii) to derive a grade of said memory device from said value.