Methods for adaptively programming flash memory devices and flash memory systems incorporating same

• US 8,799,563 B2
• Filed: 07/31/2013
• Issued: 08/05/2014
• Est. Priority Date: 10/22/2007
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: DensBits Technologies Ltd. (Broadcom, Inc.)
• Inventors: Sabbag, Erez, Katz, Michael, Weingarten, Hanan
• Primary Examiner(s): Bragdon, Reginald
• Assistant Examiner(s): Ahmed, Hamdy S
• Application Number:
  US13/956,260
• Publication Number:
  US 20130339586A1
• Time in Patent Office: 370 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: G11C 11/5628 Programming or writing circuits; Data input circuits
• CPC Class Codes: G11C 16/10 Programming or data input circuits
• CPC Class Codes: G11C 16/3418 Disturbance prevention or evaluation; Refreshing of disturbed memory data
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles

Abstract

A method for programming data into a first plurality of rows within a second plurality of erase sectors of a flash memory device using a programming process having at least one selectable parameter, the method includes characterizing each of at least one row subsets, each row subset comprising at least one row from among said first plurality of rows, thereby to generate at least one row subset characteristic value; and programming data into at least a portion of at least one individual row belonging to at least one row subset, using a programming process having at least one selectable parameter, said at least one selectable parameter being set at least partly in accordance with the row subset characteristic value characterizing a row subset to which said individual row belongs; wherein at least two row subsets of an array of flash memory cells differ from each other by their row subset characteristic values.

Claims

1. A method for programming a plurality of data sequences into a corresponding plurality of flash memory functional units using a programming process having at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, the method comprising:

providing at least one indication of at least one varying situational characteristic;

determining a value for said at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, for each flash memory functional unit, depending at least partly on said indication of said varying characteristic;

and for each individual flash memory functional unit from among said plurality of flash memory functional units, programming a sequence of bits into said individual flash memory functional unit using a programming process having at least one selectable parameter, said at least one selectable parameter being set at said value determined for said individual flash memory functional unit;

wherein the varying situational characteristic is a degradation state of at least one of the flash memory functional units.

2. A method according to claim 1 wherein said varying situational characteristic comprises a varying characteristic of each flash memory functional unit from among said plurality of flash memory functional units.

3. A method according to claim 1 wherein said at least one indication comprises a program/erase cycle count of an individual flash memory functional unit;

wherein the program/erase counts erase program cycles, each erase program cycle comprises erasing a block of cells and subsequently writing new data into at least some of the cells of the block of cells.

4. A method according to claim 1 wherein said programming process comprises generating at least two pulses and wherein said selectable parameter comprises the difference between the said two pulses.

5. A method according to claim 1 wherein said flash memory functional unit comprises an entire flash memory device.

6. A method according to claim 1 wherein said flash memory functional unit comprises an erase sector.

7. A method according to claim 1 wherein said flash memory functional unit comprises at least one row in a flash memory erase sector.

8. A system for programming a plurality of data sequences using a programming process having at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, the system comprising:

a plurality of flash memory functional units into which the plurality of data sequences are to be programmed;

a situational analyzer operative to provide at least one indication of at least one varying situational characteristic and to determine a value for said at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, for each flash memory functional unit, depending at least partly on said indication of said varying characteristic; and

a bit sequence programmer operative, for each individual flash memory functional unit from among said plurality of flash memory functional units, to program a sequence of bits into said individual flash memory functional unit using a programming process having at least one selectable parameter which is set at said value determined for said individual flash memory functional unit;

wherein the varying situational characteristic a degradation state of at least one of the flash memory functional units.

9. The system according to claim 8 wherein said at least one indication comprises a program/erase cycle count of an individual flash memory functional unit;

wherein the program/erase counts erase program cycles, each erase program cycle comprises erasing a block of cells and subsequently writing new data into at least some of the cells of the block of cells.

10. The system according to claim 8 wherein said flash memory functional unit comprises an entire flash memory device.

11. The system according to claim 8 wherein said flash memory functional unit comprises at least one row in a flash memory erase sector.

12. A method for programming a plurality of data sequences into a corresponding plurality of flash memory functional units using a programming process having at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, the method comprising:

providing at least one indication of at least one varying situational characteristic;

determining a value for said at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, for each flash memory functional unit, depending at least partly on said indication of said varying characteristic; and

for each individual flash memory functional unit from among said plurality of flash memory functional units, programming a sequence of bits into said individual flash memory functional unit using a programming process having at least one selectable parameter, said at least one selectable parameter being set at said value determined for said individual flash memory functional unit;

wherein the varying situational characteristic is at least one characteristic of an application to which a flash memory functional unit of the plurality of flash memory functional units has been assigned.

13. The method according to claim 12 wherein said characteristic of said application comprises a duration of time for which information in said flash memory functional unit is to be maintained.

14. A non-transitory computer usable medium having embodied therein program code that once executed by the computer cause the computer to execute the stages of:

providing at least one indication of at least one varying situational characteristic;

determining a value for at least one selectable programming duration-controlling parameter controlling a duration of a programming process for a given data sequence, for each flash memory functional unit, depending at least partly on said indication of said varying characteristic; and

for each individual flash memory functional unit from among a plurality of flash memory functional units, programming a sequence of bits into said individual flash memory functional unit using a programming process having at least one selectable parameter, said at least one selectable parameter being set at said value determined for said individual flash memory functional unit;

wherein the varying situational characteristic is a degradation state of at least one of the flash memory functional units.

15. The non-transitory computer usable medium according to claim 14 wherein said at least one indication comprises a program/erase cycle count of an individual flash memory functional unit;

wherein the program/erase counts erase program cycles, each erase program cycle comprises erasing a block of cells and subsequently writing new data into at least some of the cells of the block of cells.

16. A non-transitory computer usable medium having embodied therein program code that once executed by the computer cause the computer to execute the stages of:

providing at least one indication of at least one varying situational characteristic;

determining a value for at least one selectable programming duration-controlling parameter controlling a duration of a programming process for a given data sequence, for each flash memory functional unit, depending at least partly on said indication of said varying characteristic; and

for each individual flash memory functional unit from among a plurality of flash memory functional units, programming a sequence of bits into said individual flash memory functional unit using a programming process having at least one selectable parameter, said at least one selectable parameter being set at said value determined for said individual flash memory functional unit;

wherein the varying situational characteristic is at least one characteristic of an application to which a flash memory functional unit of the plurality of flash memory functional units has been assigned.

17. The non-transitory computer usable medium according to claim 16 wherein said characteristic of said application comprises a duration of time for which information in said flash memory functional unit is to be maintained.

18. A system for programming a plurality of data sequences using a programming process having at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, the system comprising:

a plurality of flash memory functional units into which the plurality of data sequences are to be programmed;

a situational analyzer operative to provide at least one indication of at least one varying situational characteristic and to determine a value for said at least one selectable programming duration-controlling parameter controlling the duration of the programming process for a given data sequence, for each flash memory functional unit, depending at least partly on said indication of said varying characteristic; and

a bit sequence programmer operative, for each individual flash memory functional unit from among said plurality of flash memory functional units, to program a sequence of bits into said individual flash memory functional unit using a programming process having at least one selectable parameter which is set at said value determined for said individual flash memory functional unit;

wherein the varying situational characteristic is at least one characteristic of an application to which a flash memory functional unit of the plurality of flash memory functional units has been assigned.

19. The system according to claim 18 wherein said characteristic of said application comprises a duration of time for which information in said flash memory functional unit is to be maintained.