Granted Patent B2

US 7,649,782 · App. 11/831,168 · Granted Jan 19, 2010

Abstract

Claims (53)

1. A method for performing an erase operation in a non-volatile memory, comprising:

selecting a block on which to perform an erase operation;

erasing the selected block;

receiving test data corresponding to the selected block;

determining a soft program verify voltage level based on the test data; and

soft programming the erased selected block using the soft program verify voltage level.

2. The method of claim 1 , wherein the determining the soft program verify voltage level comprises selecting the soft program verify voltage level from a plurality of soft program verify voltage levels.

3. The method of claim 1 , wherein the determining the soft program verify voltage level comprises:

determining a soft program reference voltage; and

generating a soft program verify voltage at the soft program verify voltage level using the soft program reference voltage.

4. The method of claim 1 , wherein the soft programming the erased selected block comprises:

determining that a cell of the erased selected block fails the soft program verify voltage level;

applying a soft program voltage pulse to the cell; and

determining whether the cell fails or passes the soft program verify voltage level.

5. The method of claim 4 , wherein erasing the selected block comprises:

applying erase pulses to each cell of the selected block until each cell passes a predetermined erase verify voltage level, wherein the soft program verify voltage level is less than the erase verify voltage level.

6. The method of claim 5 , further comprising:

prior to erasing the selected block, programming each cell of the selected block which fails a predetermined program verify voltage level, wherein the erase verify voltage level is less than the program verify voltage level.

7. The method of claim 1 , wherein the test data comprises a program/erase cycle count for the selected block, and wherein the soft program verify voltage level is determined based at least in part on the program/erase cycle count.

8. The method of claim 7 , further comprising:

updating the program/erase cycle count for the selected block; and

storing the updated program/erase cycle count.

9. The method of claim 7 , wherein the test data further comprises a block size for the selected block, and wherein the soft program verify voltage level is determined based at least in part on the program/erase cycle count and the block size.

10. The method of claim 1 , wherein the test data indicates an expected number of program/erase cycles to be performed on the selected block, and wherein the soft program verify voltage level is determined based at least in part on the expected number of program/erase cycles to be performed on the selected block.

11. A method for performing an erase operation in a non-volatile memory, comprising:

selecting a block on which to perform an erase operation;

erasing the selected block;

receiving a program/erase cycle count corresponding to the selected block;

determining a soft program verify voltage level based at least in part on the program/erase cycle count; and

soft programming the erased selected block using the soft program verify voltage level.

12. The method of claim 11 , further comprising:

increasing the program/erase cycle count; and

storing the increased program/erase cycle count.

13. The method of claim 12 , further comprising performing a second erase operation on the selected block, wherein the performing the second erase operation on the selected block comprises:

erasing the selected block;

receiving the increased program/erase cycle count corresponding to the selected block;

determining a second soft program verify voltage level based at least in part on the increased program/erase cycle count, wherein the second soft program verify voltage level is different from the soft program verify voltage level; and

soft programming the erased selected block using the second soft program verify voltage level.

14. The method of claim 11 , wherein the determining the soft program verify voltage level comprises determining the soft program verify voltage level based at least in part on the program/erase cycle count and a block size of the selected block.

15. The method of claim 11 , wherein the soft programming the erased selected block comprises:

determining that a cell of the erased selected block fails the soft program verify voltage level;

applying a soft program voltage pulse to the cell; and

determining whether the cell fails or passes the soft program verify voltage level.

16. The method of claim 15 , wherein erasing the selected block comprises:

applying erase pulses to each cell of the selected block until each cell passes a predetermined erase verify voltage level, wherein the soft program verify voltage level is less than the erase verify voltage level.

17. A non-volatile memory comprising:

a plurality of blocks;

a test block, wherein the test block stores test data corresponding to each of the plurality of blocks; and

a flash control coupled to the plurality of blocks and the test block, the flash control determining a soft program verify voltage level for a particular block of the plurality of blocks based on the test data for the particular block when the particular block is being soft programmed.

18. The non-volatile memory of claim 17 , wherein the stored tests data stores a program/erase cycle count for each of the plurality of blocks.

19. The non-volatile memory of claim 17 , wherein the stored tests data indicates an expected number of program/erase cycles to be performed on each of the plurality of blocks.

20. The non-volatile memory of claim 17 , further comprising:

a charge pump coupled to the plurality of blocks, the charge pump providing a soft program verify voltage to the particular block at the determined soft program verify voltage level when the particular block is being soft programmed.

Assignments (15)