Adaptive write procedures for non-volatile memory using verify read
View Patent ↗A method includes performing a write operation on memory cells of a memory array to a first logic state using a voltage of a charge pump. A portion of the write operation is performed on the memory cells of the memory array using the voltage of the charge pump. A determination is made if the voltage insufficient for performing the write operation on the memory cells of the memory array. If a level of the voltage is insufficient, the write operation is continued with an increased level of the voltage by reducing load on the charge pump by providing the voltage on a reduced number of memory cells. The reduced number of memory cells is a first subset of the memory cells.
1. A method of performing a write operation on memory cells of a memory array to a first logic state using a voltage of a charge pump, the method comprising:
performing a portion of the write operation on the memory cells of the memory array using the voltage of the charge pump;
determining if the voltage is insufficient for performing the write operation on the memory cells of the memory array; and
if a level of the voltage is insufficient, continuing the write operation with an increased level of the voltage by reducing load on the charge pump by providing the voltage on a reduced number of memory cells, wherein the reduced number of memory cells is a first subset of the memory cells.
2. The method of claim 1 , wherein the performing the write operation comprises performing a program procedure.
3. The method of claim 2 , wherein the memory cells are arranged in a plurality of pages, wherein each page has a plurality of the memory cells, wherein the determining comprises testing the plurality of memory cells of a first page of the plurality of pages and if the plurality of memory cells of the first page do not obtain a predetermined level of programming, the voltage level is determined to be insufficient.
4. The method of claim 1 , wherein the performing the portion of the write operation comprises performing an erase procedure.
5. The method of claim 1 , wherein the performing the portion of the write operation is further characterized by the write operation comprising one of a group consisting of a soft programming procedure and a pre-programming procedure.
6. The method of claim 1 , wherein the write operation further comprises:
completing the write operation on the first subset of the memory cells using the voltage, and
performing the write operation on a second subset of the memory cells using the voltage.
7. The method of claim 6 , wherein the determining if the voltage is insufficient comprises testing at a least a portion of the memory cells to see if sufficient progress has been made for a duration of the write operation that has occurred.
8. The method of claim 7 , wherein the testing comprises determining if a first threshold voltage has been achieved for the portion of the memory cells.
9. The method of claim 1 , wherein the performing a portion of the write operation comprises beginning an erase procedure, further comprising:
after continuing the write operation, determining if the voltage being used on the first subset of memory cells is insufficient for performing the write operation on the first subset memory cells; and
if the voltage being used on the first subset of memory cells is insufficient, continuing the write operation using the voltage of the charge pump on a second subset of the memory cells, wherein the second subset is a subset of the first subset.
10. The method of claim 9 , further comprising:
completing erasing the second subset of memory cells; and
completing erasing the memory cells by sequentially erasing groups of memory cells, wherein each group has a same number of memory cells as the second subset.
11. The method of claim 10 , wherein the write operation further comprises:
pre-programming the memory cells prior to beginning the erase procedure; and
soft programming selected memory cells after the completing the erasing of the memory cells.
12. A method of performing a write operation on memory cells of a memory array to a first logic state using a voltage of a charge pump, the method comprising:
performing a portion of the write operation on the memory cells of the memory array using the voltage of the charge pump;
determining if the memory cells are providing an excessive load on the charge pump by testing at least a portion of the memory cells to see if sufficient writing has occurred; and
if the load is excessive, continuing the write operation on a decreased number of the memory cells, wherein the decreased number of the memory cells comprise a subset of the memory cells.
13. The method of claim 12 , wherein the testing comprises detecting if a predetermined threshold voltage has been reached by the memory cells.
14. The method of claim 13 , wherein the write operation comprises a program operation.
15. The method of claim 13 , wherein the write operation comprises an erase operation.
16. The method of claim 15 , wherein continuing the write operation comprises completing an erase procedure.
17. The method of claim 15 , wherein continuing the writing operation comprises:
performing a portion of an erase procedure;
determining if the first subset of memory cells are providing an excessive load on the charge pump by testing at least a portion of the first subset of memory cells to see if sufficient writing has occurred; and
if the load of the first subset of memory cells is excessive, continuing the erase procedure on a decreased number of the memory cells relative to the first subset, wherein the decreased number of the memory cells relative to the first subset comprise a subset of the first subset of memory cells.
18. The method of claim 17 , further comprising:
completing the erase procedure on the second subset;
dividing the memory cells, less the second subset of memory cells, into groups of equal size and equal to the second subset; and
sequentially performing the erase procedure on the groups.
19. A non-volatile memory system, comprising:
an array of memory cells that are non-volatile;
charge pumps that have outputs that provide voltages; and
a controller that causes the outputs to be coupled to the memory cells to perform a write to a first logic state on the memory cells, determines if loading by the memory cells results in insufficient writing, and if insufficient writing occurs when the output is coupled to the memory cells, then the output is coupled to a first subset of the memory cells to reduce loading on the output and thereby raising a level of the voltage.
20. The non-volatile memory system of claim 19 , wherein the controller determines if the loading by the memory results in insufficient writing by determining if threshold voltages of memory cells has failed to reach a predetermined level.