Partial block data programming and reading operations in a non-volatile memory

• US 7,657,702 B2
• Filed: 02/13/2009
• Issued: 02/02/2010
• Est. Priority Date: 01/19/2001
• Status: Expired due to Fees

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Conley, Kevin M.
• Primary Examiner(s): Kim, Hong
• Assistant Examiner(s): Dinh, Ngoc V
• Application Number:
  US12/371,460
• Publication Number:
  US 20090150601A1
• Time in Patent Office: 354 Days
• Field of Search: 711/103
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/1032 Reliability improvement, data loss prevention, degraded operation etc
• CPC Class Codes: G06F 2212/7202 Allocation control and policies
• CPC Class Codes: G06F 2212/7208 Multiple device management, e.g. distributing data over multiple flash devices
• CPC Class Codes: G06F 2212/7209 Validity control, e.g. using flags, time stamps or sequence numbers
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: G11C 16/105 Circuits or methods for updating contents of nonvolatile memory, especially with 'security' features to ensure reliable replacement, i.e. preventing that old data is lost before new data is reliably written
• CPC Class Codes: G11C 2216/16 Flash programming of all the cells in an array, sector or block simultaneously

Abstract

Data in less than all of the pages of a non-volatile memory block are updated by programming the new data in unused pages of either the same or another block. In order to prevent having to copy unchanged pages of data into the new block, or to program flags into superceded pages of data, the pages of new data are identified by the same logical address as the pages of data which they superceded and a time stamp is added to note when each page was written. When reading the data, the most recent pages of data are used and the older superceded pages of data are ignored. This technique is also applied to metablocks that include one block from each of several different units of a memory array, by directing all page updates to a single unused block in one of the units.

Claims

1. In a re-programmable non-volatile semiconductor memory system having an array of charge storage elements, the array being divided into a plurality of sub-arrays in which the charge storage elements within individual sub-arrays are programmable independently, wherein the sub-arrays are individually divided into a plurality of blocks of charge storage elements that are erasable together, a method of operating the memory system, comprising:

utilizing at least first and second of the plurality of blocks logically linked together as a metablock, the logically linked first and second of the plurality of blocks being positioned in at least respective first and second of the plurality of sub-arrays, the plurality of blocks being individually divided into a given number of a plurality of pages of charge storage elements that are programmable together,

programming a first group of a plurality of pages in at least the first and second blocks with original data, the pages of original data having logical addresses associated therewith,

maintaining an updatable address data structure that links one or more physical addresses of the first group of pages with one or more of the logical addresses associated with the data stored therein,

programming an updated version of some of the original data and logical addresses associated with the updated version of the original data into a second group of one or more pages less than said given number in at least one update block other than the first and second blocks, wherein the logical addresses associated with the updated version of the original data programmed into the second group of pages are the same as those associated with the corresponding original data programmed into the first group of pages, and further wherein programming the second group of pages additionally comprises programming the updated version of the original data in those of the second group of pages that have different offset positions within the update block than offset positions of the first group of pages within the first and second blocks that contain original data having the same logical addresses associated therewith, and

updating the address data structure for the logical addresses of the updated version of the original data to include the physical addresses of the second group of pages of the update block in which the updated version of the original data has been programmed.

2. The method of claim 1, wherein logically linking the first and second of the plurality of blocks includes erasing the charge storage elements of the first and second of the plurality of blocks together and concurrently programming at least one of the plurality of pages of each of the first and second of the plurality of blocks.

3. The method of claim 1, additionally comprising:

thereafter accessing the address data structure with the logical addresses of the pages of data to be read and thereby determine physical addresses of those of at least the first and second groups of pages containing the data to be read,

reading the data from the pages of the first and second blocks having the determined physical addresses, and

organizing the read data by the logical addresses associated therewith.

4. The method of claim 3, wherein reading data and organizing the read data together comprise:

for data having the same logical addresses associated therewith, reading the updated version of the original data and omitting use of the original data, and

reading the original data from pages that have not been updated.

5. The method of claim 1, wherein the at least one update block is positioned within one of said at least first and second sub-arrays, and wherein programming the updated version of the original data stored in either of said first and second blocks includes programming such updated version of the original data in the update block.

6. The method of claim 1, additionally comprising:

programming a second updated version of some of the original data and logical addresses associated with the second updated version of the original data into a third group of one or more pages less than said given number in the update block, and

updating the address data structure for the logical addresses of the second updated version of the original data to include the physical addresses of the third group of pages of the update block in which the second updated version of the original data has been programmed.

7. The method of claim 6, additionally comprising:

thereafter accessing the address data structure with the logical addresses of the pages of data to be read and thereby determine physical addresses of at least the first, second and third groups of pages containing data to be read,

reading the data from the pages of the first, second and third blocks having the determined physical addresses, and

organizing the read data read by the logical addresses associated therewith.

8. The method of claim 7, wherein the data reading and organizing together comprises:

for data having the same logical addresses associated therewith, reading the updated version or the second updated version of the original data and omitting use of the original data that has been updated, and

reading the original data from pages that have not been updated.

9. The method of claim 6, wherein the update block is positioned within one of said at least first and second sub-arrays, and wherein programming the updated version and the second updated version of the original data stored in either of the first and second blocks includes programming both the updated version and the second updated version of the original data in only the update block.

10. The method of claim 1, wherein programming an updated version of some of the original data includes programming the updated version into update blocks within each of a plurality of sub-arrays.

11. The method of any one of claim 1, wherein programming the first group of plurality of pages with original data additionally comprises programming the logical addresses into the first group of plurality of pages along with the pages of original data with which the logical addresses are associated.

12. The method of any one of claims 1-11, wherein the logical addresses associated with the original data and updated version of the original data individually include a logical block number and a logical page offset.

13. The method of any one of claims 1-11, additionally comprising operating the individual memory system charge storage elements with more than two storage states in order to store more than one bit of data per charge storage element.

14. The method of any one of claims 1-11, wherein the memory system in which the method is practiced is contained within an enclosed card having electrical contacts accessible from outside thereof for operably connecting the memory system with a host system.

15. The method of claim 1, wherein the charge storage elements of the memory system in which the method is carried out comprise electrically conductive floating gates.

16. In a re-programmable non-volatile semiconductor memory system having a plurality of blocks of a minimum number of memory charge storage elements that are erasable together as a unit, the plurality of blocks individually being divided into a plurality of a given number of pages of memory storage elements that are individually programmable as a unit and which have specified offset positions within their respective blocks, a method of operating the memory system, comprising:

programming original data into individual ones of a first plurality of pages in at least a first block, the original data having logical addresses associated therewith,

thereafter programming, into individual ones of a second plurality of pages in a second block, an updated version of less than the given number of pages of the original data programmed into the first plurality of pages, the updated version of the original data having logical addresses associated therewith, wherein the logical addresses associated with the updated version of the original data are the same as the logical addresses associated with the original data,

wherein programming the second plurality of pages additionally comprises programming the updated version of the original data in those of the second plurality of pages that have different offset positions within the second block than the offset positions of the first plurality of pages within said at least the first block that contain original data with the same associated logical addresses,

maintaining updatable address information that links physical addresses of the first and second blocks storing original and updated data with the logical addresses associated with the stored data, wherein the address information includes physical addresses of multiple blocks for individual logical addresses of original data having updated versions thereof, and

thereafter reading data from the first and second plurality of pages by a process that includes accessing the updatable address information.

17. The method of claim 16, wherein the logical addresses are programmed into the first and second blocks along with the data with which the logical addresses are associated.

18. The method of claim 17, wherein the logical addresses associated with the data individually includes a logical block number and a logical page offset.

19. The method of claim 17, wherein maintaining the updatable address information includes constructing a form thereof by reading the logical addresses from the first and second blocks.

20. The method of claim 16, additionally comprising organizing pages of read data by their associated logical addresses, and further wherein reading data and organizing pages of the read data by their associated logical addresses comprises, for the pages of read data having the same logical addresses associated therewith, utilizing the pages of the updated version of the original data and omitting use of the pages of original data, and, for the pages of read data that are original data that have not been updated, utilizing said pages of original data that have not been updated.

21. The method of any one of claims 16-20, additionally comprising operating the individual memory system charge storage elements with more than two storage states in order to store more than one bit of data per charge storage element.

22. The method of any one of claims 16-20, wherein the memory system in which the method is practiced is contained within an enclosed card having electrical contacts accessible from outside thereof for operably connecting the memory system with a host system.

23. The method of claim 16, wherein the charge storage elements of the memory system in which the method is carried out comprise electrically conductive floating gates.

24. A re-programmable non-volatile memory system, comprising:

a plurality of blocks of re-programmable non-volatile storage elements, wherein the storage elements of individual blocks are erasable together as a unit, the individual blocks being divided into a plurality of a given number of pages of storage elements that have specified offset positions within their respective blocks and which are programmable in a preset order within the individual blocks,

an interface through which pages of user data, logical addresses associated with the pages of user data, commands and status signals pass,

a memory controller connected with the interface and with the plurality of blocks of storage elements, the memory controller being characterized by performing at least the following operations;

(a) responds to receipt through the interface of a plurality of pages of original user data, logical addresses associated with the individual pages of original user data and a command to program the received pages of original user data in the memory system by programming the received plurality of pages of original user data into a first plurality of pages of storage elements in the preset order in at least a first one of the blocks,

(b) responds to receipt through the interface of one or more pages of updated user data, one or more logical addresses that are common with the logical addresses associated with the received individual pages of original user data previously programmed, and a command to program the received pages of updated user data in the memory system by programming the received one or more pages of updated user data into a second one or more pages of storage elements in the preset order in at least a second one of the blocks without the necessity of programming the individual one or more pages of updated user data in pages of storage elements having the same offset positions within the at least the second one of the blocks as offset positions of the pages of storage elements in the at least the first one of the blocks containing pages of original data that are being updated, and

(c) responds to receipt though the interface of a command to read user data and logical addresses associated with the individual pages the data to be read by reading at least the one or more pages of updated data from the at least the second one of the blocks with which some of the received read logical addresses are associated and by reading pages of original data that have not been updated from the at least the first one of the blocks with which others of the received read logical addresses are associated.

25. The memory system of claim 24, wherein as part of operation (c), the memory controller is further characterized by controlling operation of the memory system to assemble the read pages of updated data and read pages of original data not updated in an order of the logical addresses associated therewith.

26. The memory system of claim 24, wherein as part of operation (b), the memory controller is further characterized by causing the one or more logical addresses that are common with the logical addresses associated with the individual pages of original data previously programmed to also be programmed into those of the second one or more pages of storage elements along with the pages of updated data with which the logical addresses are associated.

27. The memory system of claim 26, wherein as part of operation (a), the memory controller is further characterized by causing the logical addresses associated with the individual pages of original data programmed into the first plurality of pages of storage elements to also be programmed into those of the first plurality of pages of storage elements along with the pages of original user data with which the logical addresses are associated.

28. The memory system of any one of claims 26-27, wherein the logical addresses that are programmed into the pages of storage elements individually include a logical block number and a logical page offset.

29. The memory system of claim 24, wherein the memory controller is further characterized by performing at least the following additional operation:

(d) responds to receipt through the interface of one or more pages of further updated user data, one or more logical addresses that are common with the logical addresses associated with the individual pages of original data and updated data previously programmed, and a command to program the received further updated data in the memory system by programming the received one or more pages of further updated data into a third one or more pages of storage elements.

30. The memory system of any one of claims 24, 25 and 29 wherein the memory controller is additionally characterized by operating the individual storage elements with more than two storage states in order to store more than one bit of data per storage element.

31. The memory system of claim 24, wherein the storage elements comprise electrically conductive floating gates.

32. The memory system of any one of claims 24-27 and 29, wherein the memory system is enclosed in a portable card and wherein the interface includes a plurality of external electrical contacts.

33. A re-programmable non-volatile memory system, comprising:

an array of re-programmable non-volatile storage elements arranged in a plurality of sub-arrays of storage elements in which programming operations may be performed independently, the sub-arrays individually being divided into a plurality of blocks of storage elements that are erasable together as a unit, the individual blocks being divided into a plurality of pages of storage elements that have specified offset positions within their respective blocks,

an interface through which pages of user data, logical addresses associated with the pages of user data, commands and status signals pass,

a memory controller connected with the interface and with the plurality of blocks of storage elements, the memory controller being characterized by performing at least the following operations;

(a) links together blocks within the plurality of sub-arrays to form a plurality of metablocks whose storage elements are erasable together and whose pages of storage elements within the linked blocks are programmable together in parallel,

(b) responds to receipt through the interface of a plurality of pages of original user data, logical addresses associated with the individual pages of original data and a command to program the received original data in the memory system by programming the received plurality of pages of original data into a first plurality of pages of storage elements in a first plurality of blocks forming a first metablock,

(c) responds to receipt through the interface of one or more pages of updated user data, one or more logical addresses that are common with the logical addresses associated with the individual pages of original data previously programmed, and a command to program the received updated data in the memory system by programming the received one or more pages of updated data into a second one or more pages of storage elements in at least a second block without the necessity of programming the individual one or more pages of updated data in pages of storage elements having the same offset positions within the at least the second one of the blocks as offset positions of the pages of storage elements in the at least the first plurality of blocks containing pages of original data that are being updated, and

(d) responds to receipt through the interface of a command to read user data and logical addresses associated with the individual pages the data to be read by reading at least the one or more pages of updated data from the at least the second block with which some of the received read logical addresses are associated and by reading pages of original data that have not been updated from the at least the first plurality of blocks with which others of the received read logical addresses are associated.

34. The memory system of claim 33, wherein as part of operation (c), the memory controller is further characterized by programming the one or more pages of updated data into individual ones of the second plurality of pages of storage elements in the at least the second block that includes a second plurality of blocks forming a second metablock.

35. The memory system of claim 33, wherein as part of operation (c), the memory controller is further characterized by programming the one or more pages of updated data into individual ones of the second plurality of pages of storage elements in only the second block.

36. The memory system of claim 33, wherein as part of operation (b), the memory controller is further characterized by programming the pages of original data in an order of their associated logical addresses.

37. The memory system of claim 33, wherein as part of operation (d), the memory controller is further characterized by controlling operation of the memory system to assemble the read pages of updated data and read pages of original data not updated in order of the logical addresses associated therewith.

38. The memory system of claim 33, wherein as part of operation (c), the memory controller is further characterized by causing the logical addresses that are common with the logical addresses associated with the individual pages of original data previously programmed to also be programmed into those of the second one or more pages of storage elements along with the pages of updated data with which the logical addresses are associated.

39. The memory system of claim 38, wherein as part of operation (b), the memory controller is further characterized by causing the logical addresses associated with the individual pages of original data programmed into the first plurality of pages of storage elements to also be programmed into those of the first plurality of pages of storage elements along with the pages of data with which the logical addresses are associated.

40. The memory system of any one of claims 38-39, wherein the logical addresses that are programmed into the pages of storage elements individually include a logical block number and a logical page offset.

41. The memory system of any one of claims 33-39 wherein the memory controller is additionally characterized by operating the individual storage elements with more than two storage states in order to store more than one bit of data per storage element.

42. The memory system of any one of claims 38-39, wherein as part of operation (d), the memory controller is further characterized by reading the logical addresses stored in the pages of storage elements from which the data are read.

43. The memory system of claim 33, wherein the storage elements comprise electrically conductive floating gates.

44. The memory system of any one of claims 33-39, wherein the memory system is enclosed in a portable card and wherein the interface includes a plurality of external electrical contacts.