Flash memory architecture with separate storage of overhead and user data

• US 8,161,229 B2
• Filed: 06/22/2009
• Issued: 04/17/2012
• Est. Priority Date: 08/25/2000
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Estakhri, Petro, Nemazie, Siamack
• Primary Examiner(s): Tran, Denise
• Application Number:
  US12/488,973
• Publication Number:
  US 20090259807A1
• Time in Patent Office: 1,030 Days
• Field of Search: None
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/214 Solid state disk
• CPC Class Codes: G06F 2212/657 Virtual address space management
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7204 Capacity control, e.g. partitioning, end-of-life degradation
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators

Abstract

A memory device has a plurality of dedicated data blocks for storing only user data and a plurality of dedicated overhead blocks for storing only overhead data. Current overhead segments of a dedicated overhead block can be consolidated and moved to a new dedicated overhead block.

Claims

1. A memory device, comprising:

a plurality of dedicated data blocks for storing only user data; and

a plurality of dedicated overhead blocks for storing only overhead data;

wherein each dedicated overhead block comprises one or more pages, each page comprising a plurality of overhead segments; and

wherein each overhead segment comprises a physical block address register that cross references overhead data to user data.

2. A memory device, comprising:

a plurality of dedicated data blocks for storing only user data; and

a plurality of dedicated overhead blocks for storing only overhead data;

wherein a dedicated overhead block comprises a first and second overhead data fields; and

wherein overhead segments within the second overhead data field are not pre-assigned to specific virtual logical block addresses.

3. A memory device, comprising:

a plurality of dedicated data blocks for storing only user data; and

a plurality of dedicated overhead blocks for storing only overhead data;

wherein a dedicated overhead block comprises a first and second overhead data fields; and

wherein the memory device is configured to store overhead data supporting a specific virtual logical block address only once within the first overhead field and to store overhead data supporting a specific virtual logical block address multiple times within the second overhead field.

4. A memory device, comprising:

a plurality of dedicated data blocks for storing only user data; and

a plurality of dedicated overhead blocks for storing only overhead data;

wherein a dedicated overhead block comprises a first and second overhead data fields;

wherein the first overhead field and the second overhead field each comprise one or more pages of overhead segments; and

wherein the memory device is configured to store a status of overhead segments within the first overhead field in an extension field at the end of each page.

5. A memory device, comprising:

a plurality of dedicated data blocks for storing only user data; and

a plurality of dedicated overhead blocks for storing only overhead data;

wherein a dedicated overhead block comprises a first and second overhead data fields;

wherein the first overhead field and the second overhead field each comprise one or more pages of overhead segments; and

wherein a first segment of each page of a second overhead data field is a status segment that comprises an update map.

6. The memory device of claim 5, wherein the update map is configured to locate all current overhead segments, regardless of whether in the first overhead field or the second overhead field, where a current overhead segment is an overhead segment that is used, non-defective, and not obsolete.

7. The memory device of claim 5, wherein an update map comprises a number of registers equal in number to a number of overhead segments in the first overhead field.

8. A memory device, comprising:

a plurality of dedicated data blocks for storing only user data; and

a plurality of dedicated overhead blocks for storing only overhead data;

wherein each of the plurality of dedicated overhead blocks comprises a first overhead field and a second overhead field, the first and second overhead fields comprising a plurality of consecutively addressable overhead pages;

wherein consecutively addressable segments of the consecutively addressable overhead pages within the first overhead field of a dedicated overhead block are respectively correlated to sequentially addressed virtual logical block addresses; and

wherein overhead segments within the second overhead data field are not pre-assigned to specific virtual logical block addresses.

9. The memory device of claim 8, wherein consecutively addressable segments of the consecutively addressable overhead pages within an overhead page of the second overhead field comprise a status segment and a plurality of overhead segments, the status segment defined according to a lowest segment address among a plurality of segments within the overhead page of the second overhead field.

10. The memory device of claim 9, wherein status segments and the overhead segments comprise flags.

11. A memory device, comprising:

a plurality of dedicated data blocks for only storing user data; and

a plurality of dedicated overhead blocks for only storing overhead data;

wherein each dedicated overhead block comprises a plurality of super overhead fields, a super overhead field comprising a whole number of pages, each super overhead field within a dedicated overhead block comprising an identical number of pages, wherein consecutive overhead segments within a page are respectively assigned to consecutively addressed virtual logical block addresses of a plurality of virtual logical blocks of user data.

12. The memory device of claim 11, wherein each overhead segment comprises a flag field, comprising a move-pending flag and a move-complete flag.

13. The memory device of claim 12, wherein the flag field further comprises a used flag, an obsolete flag, and a defective flag.

14. The memory device of claim 11, wherein each page comprises an extension field for storing a super virtual logical block address that corresponds to the dedicated overhead block.

15. The memory device of claim 14, wherein the memory device is configured to use information stored in the extension field to correlate logical and physical addresses within a space manager of the memory device on power up.

16. The memory device of claim 11, wherein an address specifier of a space manager of the memory device is configured to reference a number of a page currently in use in a dedicated overhead block.

17. A method of operating a memory device, comprising:

receiving user data from a host defined according to a first virtual logical block address;

identifying a first available overhead segment of a plurality of overhead segments within a first dedicated overhead block, the first available overhead segment comprising a lowest addressable available overhead segment within the first dedicated overhead block, an available overhead segment comprising an overhead segment that is unused, non-defective, and not obsolete;

storing the user data in a first dedicated data block of the memory device defined according to a first virtual physical block address; and

storing an address of the first dedicated data block in a physical address register of the first available overhead segment.

18. The method of claim 17, further comprising consolidating all current overhead segments within the first dedicated overhead block into consecutive overhead segments within a second dedicated overhead block, a current overhead segment comprising an overhead segment that is used, non-defective, and not obsolete.

19. The method of claim 18, wherein consolidated consecutive overhead segments within the second dedicated overhead block are in the same respective columns as the current overhead segments within the first dedicated overhead block.

20. The method of claim 18, wherein consolidating all current overhead segments within the first dedicated overhead block into consecutive overhead segments within the second dedicated overhead block, comprises:

moving data stored within a first current overhead segment within the first dedicated overhead block into a lowest addressable available overhead segment within the second dedicated overhead block; and

erasing the first dedicated overhead block.

21. The method of claim 20, further comprising writing overhead data into a last addressable segment of the first dedicated overhead block before consolidating all current overhead segments within the first dedicated overhead block into consecutive overhead segments within the second dedicated overhead block.

22. The method of claim 20, wherein moving data stored within the first current overhead segment within the first dedicated overhead block into the lowest addressable available overhead segment within the second dedicated overhead block comprises:

examining selected flags within selected overhead segments within the first dedicated overhead block; and

examining selected flags within selected overhead segments within the second dedicated overhead block.

23. The method of claim 17, wherein each of the plurality of overhead segments comprises a flag field, comprising a used flag, an obsolete flag, and a defective flag.

24. The method of claim 23, further comprising setting a used flag within the first available overhead segment to indicate that overhead data has been stored in the first available overhead segment.

25. The method of claim 17, wherein identifying the first available overhead segment comprises examining selected flags within selected overhead segments within the first dedicated overhead block.