Erase block data splitting

• US 6,906,961 B2
• Filed: 06/24/2003
• Issued: 06/14/2005
• Est. Priority Date: 06/24/2003
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Eggleston, David, Murray, Michael, Moschopoulos, Anthony, Keays, Brady
• Primary Examiner(s): Elms, Richard
• Assistant Examiner(s): Luu, Pho M.
• Application Number:
  US10/602,991
• Publication Number:
  US 20040264254A1
• Time in Patent Office: 721 Days
• Field of Search: 365/185.29, 365/185.33, 365/230.01, 365/230.04
• US Class Current: 365/185.29
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G11C 16/16 for erasing blocks, e.g. arrays, words, groups

Abstract

A Flash memory device, system, and data handling routine is detailed with a distributed erase block sector user/overhead data scheme that splits the user data and overhead data and stores them in differing associated erase blocks. The erase blocks of the Flash memory are arranged into associated erase block pairs in “super blocks” such that when user data is written to/read from the user data area of a sector of an erase block of the super block pair, the overhead data is written to/read from the overhead data area of a sector of the other associated erase block. This data splitting enhances fault tolerance and reliability of the Flash memory device.

Claims

1. A Flash memory system comprising:

at least one Flash memory device, wherein the at least one Flash memory device contains a memory array with a plurality of floating gate memory cells arranged in a plurality of erase blocks, and wherein each erase block of the plurality of erase blocks contains a plurality of sectors, and each sector contains a user data area and an overhead data area;

wherein the erase blocks of the at least one Flash memory device are arranged in pairs into a plurality of super blocks; and

a control circuit adapted to control data accesses to the sectors of the erase block pair of a selected super block such that user data access and overhead data accesses are directed to differing erase blocks of the super block.

2. The Flash memory system of claim 1, wherein the data access is one of a write access and a read access.

3. The Flash memory system of claim 1, wherein at least one super block of the plurality of super blocks contains erase blocks from a first Flash memory device and a second Flash memory device.

4. The Flash memory system of claim 1, wherein each super block of the plurality of super blocks contain two or more erase blocks.

5. The Flash memory system of claim 1, wherein the Flash memory system is one of a PCMCIA-ATA compatible system, a Compact Flash (CF) card, a USB Flash card, and a multimedia card (MMC).

6. The Flash memory system of claim 1, wherein each erase block of the plurality of erase blocks contains at least 16 sectors, and each sector contains a user data area of at least 512 bytes and an overhead data area.

7. The Flash memory system of claim 1, wherein each sector is adapted to contain multiple logical sectors.

8. The Flash memory system of claim 1, wherein the control circuit includes a dedicated data splitting circuit that is adapted to split data accesses to the sectors of the erase block pair of a super block of the plurality of super blocks such that the user data access and overhead data access are directed to differing erase blocks of the super block.

9. The Flash memory system of claim 1, wherein the plurality of sectors of each erase block are sequentially addressed and wherein the control circuit is adapted to access the overhead data area of a sector m of one erase block of the super block when a user data area of a selected sector m of the other erase block of the super block is accessed.

10. The Flash memory system of claim 1, wherein the plurality of sectors of each erase block are sequentially addressed 0 to x, where x is the address of the highest addressed sector of each erase block and wherein the control circuit is adapted to access the overhead data area of a sector x−

m of one erase block of the super block when a user data area of a selected sector m of the other erase block of the super block is accessed.

11. The Flash memory system of claim 1, wherein the plurality of sectors of each erase block in the super block are sequentially addressed, with one erase block holding even addressed sectors and the other erase block holding odd addressed sectors, and wherein the control circuit is adapted to access the overhead data area of a sector m+1 when a user data area of a selected sector m is accessed.

12. The Flash memory system of claim 11, wherein the user data area of the selected sector m is accessed simultaneously with an overhead data area of a sector m−

1.

13. The Flash memory system of claim 1, wherein the plurality of erase blocks are sequentially addressed and wherein the erase block pair of each super block are addressed Erase Block N and Erase Block N+Y, where N is a base address and Y is an offset.

14. The Flash memory system of claim 1, wherein the plurality of erase blocks are sequentially addressed and wherein the erase block pair of each super block are addressed Erase Block N and Erase Block Y−

N, where N is a base address and Y is the address of the highest addressed erase block of the plurality of erase blocks.

15. The Flash memory system of claim 1, wherein the plurality of erase blocks are sequentially addressed and wherein the erase block pair of each super block are addressed Erase Block N and Erase Block N+1.

16. A non-volatile memory device comprising:

a memory array containing a plurality of floating gate memory cells arranged into a plurality of sectors in a plurality of erase blocks, each sector containing a user data area and an overhead area;

wherein the plurality of erase blocks are arranged in pairs into a plurality of super blocks; and

wherein non-volatile memory device is adapted to execute a data access such that a user data area of a selected first sector of a first erase block of a super block pair also accesses an overhead data area of an associated first sector of a second erase block of the erase block pair of the super block.

17. The non-volatile memory device of claim 16, wherein the data accesses are one of a write access and a read access.

18. The non-volatile memory device of claim 16, wherein a data splitting circuit is adapted to access the user data area of the selected first sector of the first erase block of the super block pair and to access the overhead data area of the associated first sector of the second erase block of the erase block pair.

19. The non-volatile memory device of claim 16, wherein a following data access to the super block accessing the next sequential sector address accesses the user data area of the first sector of the second erase block of the super block pair and accesses the overhead data area of the first sector of the first erase block of the erase block pair of the super block.

20. The non-volatile memory device of claim 16, wherein a following data access to the super block accessing the next sequential sector address accesses the user data area of a second sector of the second erase block of the super block pair and accesses the overhead data area of a second sector of the first erase block of the erase block pair of the super block.

21. The non-volatile memory device of claim 16, wherein a following data access to the super block accessing the next sequential sector address accesses the user data area of a second sector of the first erase block of the super block pair and accesses the overhead data area of a second sector of the second erase block of the erase block pair of the super block.

22. A Flash memory device comprising:

a memory array with a plurality of floating gate memory cells arranged in a plurality of erase blocks, wherein the erase blocks are arranged in pairs into a plurality of super blocks, and wherein each erase block of the plurality of erase blocks contains a plurality of sectors, and each sector contains a user data area and an overhead data area; and

a control circuit adapted to perform data accesses to the sectors of the erase block pair of a super block such that user data access and overhead data accesses are directed to differing erase blocks of the super block.

23. The Flash memory device of claim 22, wherein each sector is adapted to contain multiple logical sectors in the user data area and overhead data area.

24. The Flash memory device of claim 22, wherein the control circuit includes a dedicated data splitting circuit that is adapted to split data accesses to the sectors of the erase block pair of a super block of the plurality of super blocks such that the user data access and overhead data access are directed to differing erase blocks of the super block.

25. The Flash memory device of claim 22, wherein the plurality of sectors of each erase block are sequentially addressed and wherein the control circuit is adapted to access the overhead data area of a sector m of one erase block of the super block when a user data area of a selected sector m of the other erase block of the super block is accessed.

26. The Flash memory device of claim 22, wherein the plurality of sectors of each erase block are sequentially addressed 0 to x, where x is the address of the highest addressed sector of each erase block and wherein the control circuit is adapted to access the overhead data area of a sector x−

m of one erase block of the super block when a user data area of a selected sector m of the other erase block of the super block is accessed.

27. The Flash memory device of claim 22, wherein the plurality of sectors of each erase block in the super block are sequentially addressed, with one erase block holding even addressed sectors and the other erase block holding odd addressed sectors, and wherein the control circuit is adapted to access the overhead data area of sector m+1 when a user data area of a selected sector m is accessed.

28. The Flash memory device of claim 27, wherein the user data area of the selected sector m is accessed simultaneously with an overhead data area of sector m−

1.

29. A method of operating a Flash memory system comprising:

receiving a memory access request;

accessing a user data area of a sector of an erase block of a plurality of erase blocks of one or more Flash memory devices; and

concurrently accessing an overhead data area of a sector of an associated erase block of the plurality of erase blocks.

30. The method of claim 29, wherein the erase block is from a first Flash memory device and the associated erase block is from a second Flash memory device.

31. The method of claim 29, wherein the sectors of the erase block and the associated erase block are sequentially addressed, with one erase block holding even addressed sectors and the other erase block holding odd addressed sectors.

32. The method of claim 31, wherein accessing a user data area of a sector of an erase block and concurrently accessing an overhead data area of a sector of an associated erase block further comprises concurrently accessing the overhead data area of a sector m+1 when a user data area of a selected sector m is accessed.

33. The method of claim 32, wherein the user data area of the selected sector m is accessed simultaneously with an overhead data area of a sector m−

1.

34. The method of claim 29, wherein accessing a user data area of a sector of an erase block and accessing an overhead data area of a sector of an associated erase block further comprises accessing the same relative sector address in each erase block.

35. The method of claim 29, wherein accessing a user data area of a sector of an erase block and accessing an overhead data area of a sector of an associated erase block further comprises accessing a user data area of a sector of an erase block and accessing an overhead data area of a sector of an associated erase block wherein the plurality of erase blocks are sequentially addressed and wherein the erase block and the associated erase block are addressed Erase Block N and Erase Block N+Y, respectively, where N is a base address and Y is an offset.

36. A method of operating a Flash memory device comprising:

receiving a memory access request;

accessing a user data area of a sector of an erase block of a plurality of erase blocks of a Flash memory array; and

accessing an overhead data area of a sector of an associated erase block of the plurality of erase blocks in response to accessing the user data area of the erase block.

37. The method of claim 36, wherein the erase block and the associated erase block are associated in a super block pair.

38. The method of claim 36, wherein the sectors of the erase block and the associated erase block are sequentially addressed, with one erase block holding even addressed sectors and the other erase block holding odd addressed sectors.

39. The method of claim 38, wherein accessing a user data area of a sector of an erase block and accessing an overhead data area of a sector of an associated erase block further comprises accessing the overhead data area of a sector m+1 when a user data area of a selected sector m is accessed.

40. The method of claim 36, wherein accessing a user data area of a sector of an erase block and accessing an overhead data area of a sector of an associated erase block further comprises accessing a user data area of a sector of an erase block and accessing an overhead data area of a sector of an associated erase block wherein the plurality of erase blocks are sequentially addressed and wherein the erase block and the associated erase block are addressed Erase Block N and Erase Block N+1, respectively.

41. An address control circuit comprising:

a control circuit coupled to a host interface;

a first and second address registers coupled to the control circuit;

an address multiplexer coupled to the first and second address registers and to a Flash memory interface; and

wherein the address control circuit is adapted to load a data access request containing a data address from the host interface and address sequentially addressed Flash memory physical sectors of a selected superblock as data is accessed by a host, where the superblock contains a first and second erase blocks.

42. The address control circuit of claim 41, wherein the address control circuit is adapted to sequentially access physical sectors of the first and second erase blocks in a pattern that alternates between physical sectors of the first and second erase block as the physical sectors of the superblock are sequentially accessed.

43. The address control circuit of claim 41, wherein the data access loaded from the host contains an initial address offset in an initially accessed physical sector of the superblock.

44. The address control circuit of claim 41, wherein each address register has at least a first portion and second portion.

45. The address control circuit of claim 44, wherein the first portion is adapted to contain a row address and second portion is adapted to contain a column address.

46. The address control circuit of claim 44, wherein the address control circuit is adapted to reset the second portion of the first and second address registers to zero when a physical sector boundary is crossed.

47. The address control circuit of claim 44, wherein the address control circuit is adapted to reset the first portion of the first and second address registers to zero to after a final physical sector of the superblock is accessed.

48. The address control circuit of claim 44, wherein the address control circuit is adapted to increment the first portion of the first and second address registers after a physical sector boundary of the second erase block is crossed.

49. The address control circuit of claim 44, wherein the address control circuit is adapted to switch the currently selected address register of the first and second address registers that is coupled to the Flash memory interface after a physical sector boundary of the first or second erase block is crossed.

50. A NAND Flash memory system comprising:

at least one NAND Flash memory device, wherein the at least one Flash memory device contains a NAND architecture memory array with a plurality of floating gate memory cells arranged in a plurality of erase blocks, and wherein each erase block of the plurality of erase blocks contains a plurality of physical sectors, and each physical sector contains a user data area and an overhead data area;

wherein the erase blocks of the at least one NAND Flash memory device are arranged in pairs into a plurality of super blocks;

a control circuit adapted to control data accesses to the physical sectors of the erase block pair of a selected super block; and

wherein the plurality of physical sectors of each erase block in the super block are sequentially addressed, with one erase block holding even addressed physical sectors and the other erase block holding odd addressed physical sectors, and wherein the control circuit is adapted to access the overhead data area of a physical sector m+1 when a user data area of a selected physical sector m is accessed.