Status of overall health of nonvolatile memory

• US 7,464,306 B1
• Filed: 08/27/2004
• Issued: 12/09/2008
• Est. Priority Date: 08/27/2004
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Lexar Media Incorporated (Micron Technology, Inc.)
• Inventors: Furuhjelm, Martin Ragnar, Hellmold, Steffen Markus
• Primary Examiner(s): Chung; Phung M
• Application Number:
  US10/927,871
• Time in Patent Office: 1,565 Days
• Field of Search: 714/704, 714/710, 714/718, 711/103, 711/113, 711/118, 711/170, 711/156, 365/200, 365/201
• US Class Current: 714/710
• 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 2029/5002 Characteristic
• CPC Class Codes: G11C 29/50 Marginal testing, e.g. race, voltage or current testing
• CPC Class Codes: G11C 29/56 External testing equipment for static stores, e.g. automatic test equipment [ATE]; Interfaces therefor
• CPC Class Codes: G11C 29/76 using address translation or modifications

Abstract

A nonvolatile memory system includes nonvolatile memory organized into blocks, one or more of which are designated as spare blocks and one or more of which may be defective at the time of manufacturing of the nonvolatile memory. A controller device is coupled to the nonvolatile memory for measuring the health status of the nonvolatile memory by determining the number of growing defects on an on-going basis.

Claims

1. A nonvolatile memory system comprising:

nonvolatile memory organized into blocks, one or more of which are designated as spare blocks and one or more of which may be defective at the time of manufacturing of the nonvolatile memory; and

a controller device coupled to the nonvolatile memory for measuring the health status of the nonvolatile memory by determining a number of growing defects on an on-going basis and determining a total number of remaining spare blocks at the time of the measurement of the health status by subtracting the number of defects at the time of the measurement of the health status from a total number of spare blocks within the nonvolatile memory that are initially reserved as spare blocks, wherein the total number of remaining spare blocks at the time of the measurement of the health status is indicative of the health status of the nonvolatile memory;

wherein the controller is configured to output a signal indicative of the total number of remaining spare blocks at the time of the measurement of the health status.

2. A nonvolatile memory system as recited in claim 1 wherein the controller device measures the health status using the equation,

HS=SB_rem/(SB_fw−

MD),

wherein HS is a health status of the nonvolatile memory, MD is the number of defects detected at the time of manufacturing of the nonvolatile memory, SB_fw is the total number of spare blocks within the nonvolatile memory that are initially reserved as spare blocks, and SB_rem is the total number of spare blocks remaining at the time of the measurement of the health status of the nonvolatile memory.

3. A nonvolatile memory system as recited in claim 2 wherein HS is (SB_rem/(SB_fw−

MD))*100 representing a measurement of the number of growing defects in percentage.

4. A nonvolatile memory system as recited in claim 2 wherein HS is rounded up to the next integer as follows:

int (HS+0.5).

5. A nonvolatile memory system as recited in claim 2 wherein the value of HS is displayed to a user of the nonvolatile memory system.

6. A nonvolatile memory system comprising:

nonvolatile memory organized into blocks, one or more of which are designated as spare blocks and one or more of which may be defective at the time of manufacturing of the nonvolatile memory;

a controller device coupled to the nonvolatile memory; and

a display;

wherein the controller device measures the health status of the nonvolatile memory by determining a number of growing defects on an on-going basis and determining a total number of remaining spare blocks at the time of the measurement of the health status by subtracting the number of defects at the time of the measurement of the health status from a total number of spare blocks within the nonvolatile memory that are initially reserved as spare blocks, the total number of remaining spare blocks at the time of the measurement of the health status indicative of the health status of the nonvolatile memory; and

wherein the display is configured to display a value indicative of the total number of remaining spare blocks at the time of the measurement of the health status.

7. A nonvolatile memory system as recited in claim 6 wherein the total number of remaining spare blocks at the time of the measurement of the health status comprises a number of defects detected at the time of manufacturing of the nonvolatile memory.

8. A nonvolatile memory system as recited in claim 6 wherein the controller device measures the health status of the nonvolatile memory using the equation,

HS=SB_rem/(SB_fw−

MD),

wherein HS is a health status of the nonvolatile memory, MD is the number of defects detected at the time of manufacturing of the nonvolatile memory, SB_fw is the total number of spare blocks within the nonvolatile memory that are initially reserved as spare blocks, and SB_rem is the total number of spare blocks remaining at the time of the measurement of the health status of the nonvolatile memory.

9. A nonvolatile memory system as recited in claim 8 wherein HS is (SB_rem/(SB_fw−

MD))*100 representing a measurement of the number of growing defects in percentage.

10. A nonvolatile memory system as recited in claim 8 wherein HS is rounded up to the next integer as follows:

int (HS+0.5).

11. A nonvolatile memory system as recited in claim 6 wherein the health status is reported to a host.

12. A nonvolatile memory system as recited in claim 6 wherein the display is one or more light emitting diodes (LEDs).

13. A nonvolatile memory system as recited in claim 6 wherein the display is nonvolatile.

14. A method for measuring the health of nonvolatile memory system comprising:

noting a number of blocks included within nonvolatile memory that were defective at a time of manufacturing of the nonvolatile memory;

reserving a number of spare blocks within the nonvolatile memory at the time of manufacturing of the nonvolatile memory;

measuring the health status of the nonvolatile memory during operation of the nonvolatile memory by determining a number of growing defects on an on-going basis and determining a total number of remaining spare blocks at the time of the measurement of the health status by subtracting the number of defects at the time of the measurement of the health status, including the number of blocks that were defective at the time of manufacturing, from the number of spare blocks reserved at the time of manufacturing, the total number of remaining spare blocks at the time of the measurement of the health status indicative of the health status of the nonvolatile memory;

outputting a signal indicative of the total number of remaining spare blocks at the time of the measurement of the health status.

15. A method for measuring as recited in claim 14 wherein the measuring step includes calculating the equation,

HS=SB_rem/(SB_fw−

MD),

wherein HS is a health status of the nonvolatile memory, MD is the number of blocks that were defective at the time of manufacturing of the nonvolatile memory, SB_fw is the number of spare blocks reserved at the time of manufacturing, and SB_rem is the total number of spare blocks remaining at the time of the measurement of the health status of the nonvolatile memory.

16. A method for measuring as recited in claim 14 further including the step of displaying a value representing the health status.

17. A nonvolatile memory system comprising:

nonvolatile memory organized into blocks, one or more of which are designated as spare blocks and one or more of which may be defective at the time of manufacturing of the nonvolatile memory; and

controller means coupled to the nonvolatile memory for measuring the health status of the nonvolatile memory by determining a number of growing defects on an on-going basis and determining a total number of remaining spare blocks at the time of the measurement of the health status by subtracting the number of defects at the time of the measurement of the health status from a total number of spare blocks within the nonvolatile memory that are initially reserved as spare blocks, wherein the total number of remaining spare blocks at the time of the measurement of the health status is indicative of the health status of the nonvolatile memory;

wherein the controller means is configured to output a signal indicative of the total number of remaining spare blocks at the time of the measurement of the health status.

18. A nonvolatile memory system as recited in claim 17 wherein the controller means measures the health status using the equation,

HS=SB_rem/(SB_fw−

MD),

wherein HS is a health status of the nonvolatile memory, MD is the number of defects detected at the time of manufacturing of the nonvolatile memory, SB_fw is the total number of spare blocks within the nonvolatile memory that are initially reserved as spare blocks, and SB_rem is the total number of spare blocks remaining at the time of the measurement of the health status of the nonvolatile memory.

19. A nonvolatile memory system as recited in claim 18 wherein HS is (SB_rem/(SB_fw−

MD))*100 representing a measurement of the number of growing defects in percentage.

20. A nonvolatile memory system as recited in claim 18 wherein HS is rounded up to the next integer as follows:

int (HS+0.5).

21. A nonvolatile memory system as recited in claim 17 wherein the health status is reported to a host.

22. A nonvolatile memory system comprising:

a host; and

a nonvolatile memory organized into blocks, one or more of which are designated as spare blocks and one or more of which may be defective at the time of manufacturing of the nonvolatile memory, the nonvolatile memory comprising a control device coupled to the blocks and to the host, the nonvolatile memory comprising a display;

wherein the health status of the nonvolatile memory is measured by the host by determining a number of growing defects on an on-going basis and determining a total number of remaining spare blocks at the time of the measurement of the health status by subtracting the number of defects at the time of the measurement of the health status from a total number of spare blocks within the nonvolatile memory that are initially reserved as spare blocks, wherein the total number of remaining spare blocks at the time of the measurement of the health status is indicative of the health status of the nonvolatile memory; and

wherein the display is configured to display a value indicative of the total number of remaining spare blocks at the time of the measurement of the health status.