Semiconductor memory device
A semiconductor memory device includes: first to third pages; first to third word line; and row decoder. In data writing, data is written into the first page before data is written into the second page. The row decoder is configured to apply first to third verify voltages to the gates of the first to third memory cells in a program verify operation.
1. A semiconductor memory device including a plurality of memory cells, the device comprising:
a first page associated with a first memory cell;
a second page associated with a second memory cell;
a third page associated with a third memory cell; and
a row decoder configured to apply voltages to gates of the first to third memory cells,
wherein in writing of data, data is written into the first page before data is written into the second page,
a data write operation includes a program operation and a program verify operation,
the row decoder is configured to apply a first verify voltage to the gate of the first memory cell in the program verify operation for the first page,
the row decoder is configured to apply a second verify voltage different from the first verify voltage to the gate of the second memory cell in the program verify operation for the second page,
the row decoder is configured to apply a third verify voltage different from the first and second verify voltages to the gate of the third memory cell in the program verify operation for the third page,
the second verify voltage is a value which is shifted from the first verify voltage by at least a first coefficient, and
the third verify voltage is a value which is shifted from the first verify voltage by at least a second coefficient different from the first coefficient.
2. The device according to claim 1 , wherein the second verify voltage is higher than the first verify voltage.
3. The device according to claim 1 , wherein the first and second memory cells are located in a first layer above a semiconductor substrate,
the third memory cell is located in a second layer below the first layer,
in writing of the data, data is written into the third page after data is written into the first and second pages,
the third verify voltage is lower than the second verify voltage, and
the second verify voltage is higher than the first verify voltage.
4. The device according to claim 1 , wherein the first memory cell is located in a first layer above a semiconductor substrate,
the second memory cell is located in a second layer below the first layer,
the third memory cell is located in a third layer below the second layer,
the data is written in the order of the first to third pages,
the third verify voltage is higher than the second verify voltage, and
the second verify voltage is higher than the first verify voltage.
5. The device according to claim 1 , further comprising a fourth page associated with a fourth memory cell,
wherein the first and second memory cells are located in a first layer above a semiconductor substrate,
the third and fourth memory cells are located in a second layer below the first layer,
the data is written in the order of the first to fourth pages,
the row decoder is configured to apply the third verify voltage to the gate of the third memory cell in the program verify operation for the third page, and apply the fourth verify voltage to the gate of the fourth memory cell in the program verify operation for the fourth page,
the fourth verify voltage is higher than the third verify voltage,
the third verify voltage is higher than the second verify voltage, and
the second verify voltage is higher than the first verify voltage.
6. The device according to claim 1 , further comprising:
a fourth page associated with a fourth memory cell;
a first word line coupled to the gates of the first and second memory cells; and
a second word line coupled to the gate of the third memory cell and a gate of the fourth memory cell,
wherein the first to fourth memory cells are located in a first layer above a semiconductor substrate,
the data is written into the first and second pages before data is written into the third and fourth pages,
the row decoder is configured to apply a third verify voltage to the gate of the third memory cell in the program verify operation for the third page, and apply a fourth verify voltage to the gate of the fourth memory cell in the program verify operation for the fourth pages,
the fourth verify voltage is higher than the third verify voltage,
the third verify voltage is higher than the second verify voltage, and
the second verify voltage is higher than the first verify voltage.
7. The device according to claim 1 , further comprising:
a fourth page associated with a fourth memory cell;
a first word line coupled to the gates of the first and third memory cells; and
a second word line coupled to the gate of the second memory cell and a gate of the fourth memory cells,
wherein the first to fourth memory cells are located in a first layer above a semiconductor substrate,
the data is written into the first and second pages before data is written into the third and fourth pages,
the row decoder is configured to apply a third verify voltage to the gate of the third memory cell in the program verify operations for the third page, and apply a fourth verify voltage to the gate of the fourth memory cell in the program verify operation for the fourth page,
the fourth verify voltage is higher than the third verify voltage,
the third verify voltage is lower than the second verify voltage, and
the second verify voltage is higher than the first verify voltage.
8. The device according to claim 1 , wherein the memory cells are stacked above a semiconductor substrate, and
the first coefficient and the second coefficient depend on which of the layers above the semiconductor substrate the memory cells exist.
9. The device according to claim 1 , wherein the memory cells are configured to hold 2 or more bits of data, and
the first coefficient and the second coefficient depend on data to be written into the memory cells.
10. The device according to claim 1 , wherein the first memory cell is located in a first layer above a semiconductor substrate, and
the second memory cell is located in a second layer different from the first layer above the semiconductor substrate.
11. The device according to claim 1 , wherein the first memory cell includes a plurality of memory cells sequentially stacked along layers above a semiconductor substrate, and
the second memory cell includes a plurality of memory cells sequentially stacked along the layers above the semiconductor substrate.
12. The device according to claim 11 , further comprising:
stacked layer structures in which insulating layers and first semiconductor layers are alternately stacked on the semiconductor substrate along a first direction which is perpendicular to the surface of the semiconductor substrate, the stacked layer structures having a striped shape along a second direction orthogonal to the first direction;
a word line formed on the side surfaces of the stacked layer structures;
a first selection control line formed on the side surface at one end of a first stacked layer structure and capable of selecting the first stacked layer structure; and
a second selection control line formed on the side surface at the other end of a second stacked layer structure and capable of selecting the second stacked layer structure,
wherein the stacked first semiconductor layers function as current paths of the first memory cells or the second memory cells.
13. A semiconductor memory device including a plurality of memory cells, the device comprising:
a first page associated with a first memory cell;
a second page associated with a second memory cell;
a third page associated with a third memory cell; and
a sense amplifier configured to read data from the first page and the second page to perform a program verify operation in writing of data,
wherein in writing of the data, data is written into the first page before data is written into the second page,
the sense amplifier is configured to determine data based on a first sense period in the program verify operation for the first page,
the sense amplifier is configured to determine data based on a second sense period different from the first sense period in the program verify operation for the second page,
the sense amplifier is configured to determine data based on a third sense period different from the first and second sense periods in the program verify operation for the third page,
the second sense period has a time length which is shifted from the first sense period by at least a first coefficient, and
the third sense period has a time length which is shifted from the first sense period by at least a second coefficient different from the first coefficient.
14. The device according to claim 13 , wherein the second sense period is longer than the first sense period.
15. The device according to claim 13 , wherein the first and second memory cells are located in a first layer above a semiconductor substrate,
the third memory cell is located in a second layer below the first layer,
in writing of the data, data is written into the third page after data is written into the first and second pages,
the third sense period is shorter than the second sense period, and
the second sense period is shorter than the first sense period.
16. The device according to claim 13 , wherein the first memory cell is located in a first layer above a semiconductor substrate,
the second memory cell is located in a second layer below the first layer,
the third memory cell is located in a third layer below the second layer,
the data is written in the order of the first to third pages,
the third sense period is longer than the second sense period, and
the second sense period is longer than the first sense period.
17. The device according to claim 13 , further comprising a fourth page associated with a fourth memory cell,
wherein the first and second memory cells are located in a first layer above a semiconductor substrate,
the third and fourth memory cells are located in a second layer below the first layer,
the data is written in the order of the first to fourth pages,
the sense amplifier is configured to determine data based on the third sense period in the program verify operation for the third page, and determine data based on a fourth sense period in the program verify operation for the fourth page,
the fourth sense period is longer than the third sense period,
the third sense period is longer than the second sense period, and
the second sense period is longer than the first sense period.
18. The device according to claim 13 , further comprising a fourth page associated with a fourth memory cell;
a first word line coupled to the gates of the first and second memory cells; and
a second word line coupled to the gate of the third and a gate of the fourth memory cells,
wherein the first to fourth memory cells are located in a first layer above a semiconductor substrate,
the data is written into the first and second pages before data is written into the third and fourth pages,
the sense amplifier is configured to determine data based on the third sense period in the program verify operations for the third page, and determine data based on a fourth sense period in the program verify operations for the fourth page,
the fourth sense period is longer than the third sense period,
the third sense period is longer than the second sense period, and
the second sense period is longer than the first sense period.
19. The device according to claim 13 , further comprising:
a fourth page associated with a fourth memory cell;
a first word line coupled to the gates of the first and third memory cells; and
a second word line coupled to the gate of the second memory cell and a gate of the fourth memory cell,
wherein the first to fourth memory cells are located in a first layer above a semiconductor substrate,
the data is written into the first and second pages before data is written into the third and fourth pages,
the sense amplifier is configured to determine data based on the third sense period in the program verify operation for the third page, and determine data based on a fourth sense period in the program verify operation for the fourth page,
the fourth sense period is longer than the third sense period,
the third sense period is shorter than the second sense period, and
the second sense period is longer than the first sense period.