Sense time separation in foggy-fine program to improve optimal VT width
A memory device includes a plurality of memory cells and control circuitry configured to perform a foggy-fine programming operation in which memory cells are programmed in multiple programming passes. To perform the foggy-fine programming operation, the control circuity is configured to perform a first pass of the foggy-fine programming operation on the memory cells, perform, in accordance with a first sense time, a first sensing operation on the memory cells programmed in the first pass of the foggy-fine programming operation, perform a second pass of the foggy-fine programming operation on the memory cells previously programmed in the first pass of the foggy-fine programming operation, and perform, in accordance with a second sense time, a second sensing operation on the memory cells programmed in the first pass and the second pass of the foggy-fine programming operation, wherein the second sense time is different from the first sense time.
1. A memory device, comprising:
a plurality of memory cells; and
control circuitry configured to perform a foggy-fine programming operation in which memory cells are programmed in multiple programming passes, wherein, to perform the foggy-fine programming operation, the control circuity is configured to
perform a first pass of the foggy-fine programming operation on the memory cells,
perform, in accordance with a first sense time, a first sensing operation on the memory cells programmed in the first pass of the foggy-fine programming operation,
perform a second pass of the foggy-fine programming operation on the memory cells previously programmed in the first pass of the foggy-fine programming operation, and
perform, in accordance with a second sense time, a second sensing operation on the memory cells programmed in the first pass and the second pass of the foggy-fine programming operation, wherein the second sense time is different from the first sense time.
2. The memory device of claim 1 , wherein the second sense time is longer than the first sense time.
3. The memory device of claim 1 , wherein performing the first sensing operation includes using the first sense time in a very low sense period of the first sensing operation and using a third sense time greater than the first sense time in a very high sense period of the first sensing operation.
4. The memory device of claim 3 , wherein performing the second sensing operation includes using the second sense time in a very low sense period of the second sensing operation and using a fourth sense time greater than the second sense time in a very high sense period of the second sensing operation.
5. The memory device of claim 4 , wherein each of the first, second, third, and fourth sense times are different.
6. The memory device of claim 1 , wherein the first sense time is a sum of the second sense time and a negative offset value.
7. The memory device of claim 1 , wherein the foggy-fine programming operation is a quad level cell (QLC) programming operation.
8. The memory device of claim 7 , wherein sense times used for different programmed states of the memory cells are different.
9. A method for operating a memory device including a plurality of memory cells, the method comprising:
performing a foggy-fine programming operation in which memory cells are programmed in multiple programming passes, wherein performing the foggy-fine programming operation includes
performing a first pass of the foggy-fine programming operation on the memory cells,
performing, in accordance with a first sense time, a first sensing operation on the memory cells programmed in the first pass of the foggy-fine programming operation,
performing a second pass of the foggy-fine programming operation on the memory cells previously programmed in the first pass of the foggy-fine programming operation, and
performing, in accordance with a second sense time, a second sensing operation on the memory cells programmed in the first pass and the second pass of the foggy-fine programming operation, wherein the second sense time is different from the first sense time.
10. The method of claim 9 , wherein the second sense time is longer than the first sense time.
11. The method of claim 9 , wherein performing the first sensing operation includes using the first sense time in a very low sense period of the first sensing operation and using a third sense time greater than the first sense time in a very high sense period of the first sensing operation.
12. The method of claim 11 , wherein performing the second sensing operation includes using the second sense time in a very low sense period of the second sensing operation and using a fourth sense time greater than the second sense time in a very high sense period of the second sensing operation.
13. The method of claim 12 , wherein each of the first, second, third, and fourth sense times are different.
14. The method of claim 9 , wherein the first sense time is a sum of the second sense time and a negative offset value.
15. The method of claim 9 , wherein the foggy-fine programming operation is a quad level cell (QLC) programming operation.
16. The method of claim 15 , wherein sense times used for different programmed states of the memory cells are different.
17. A memory device, comprising:
a plurality of memory cells; and
control means for performing a foggy-fine programming operation in which memory cells are programmed in multiple programming passes, wherein, to perform the foggy-fine programming operation, the control means
performs a first pass of the foggy-fine programming operation on the memory cells,
performs, in accordance with a first sense time, a first sensing operation on the memory cells programmed in the first pass of the foggy-fine programming operation,
performs a second pass of the foggy-fine programming operation on the memory cells previously programmed in the first pass of the foggy-fine programming operation, and
performs, in accordance with a second sense time, a second sensing operation on the memory cells programmed in the first pass and the second pass of the foggy-fine programming operation, wherein the second sense time is different from the first sense time.
18. The memory device of claim 17 , wherein the second sense time is longer than the first sense time.
19. The memory device of claim 17 , wherein performing the first sensing operation includes using the first sense time in a very low sense period of the first sensing operation and using a third sense time greater than the first sense time in a very high sense period of the first sensing operation, and wherein performing the second sensing operation includes using the second sense time in a very low sense period of the second sensing operation and using a fourth sense time greater than the second sense time in a very high sense period of the second sensing operation.
20. The memory device of claim 19 , wherein each of the first, second, third, and fourth sense times are different.