Sequential write and sequential write verify in memory device
View Patent ↗Some embodiments include apparatuses and methods for performing a first stage of an operation of storing information in a first memory cell and a second memory cell, and performing a second stage of the operation after the first stage to determine whether each of the first and second memory cells reaches a target state. The first memory cell is included in a first memory cell string coupled to a data line through a first select transistor. The second memory cell is included in a second memory cell string coupled to the data line through a second select transistor.
1. An apparatus comprising:
a data line;
a first memory cell included in a first memory cell string;
a second memory cell included in a second memory cell string;
a first select transistor coupled between the data line and the first memory cell string;
a second select transistor coupled between the data line and the second memory cell string;
an access line shared by the first and second memory cells; and
a module to perform a first stage of an operation of storing information in the first and second memory cells, and to perform a second stage of the operation after the first stage to determine whether each of the first and second memory cells reaches a target state.
2. The apparatus of claim 1 , wherein the module is to change a state of each of the first and second memory cells during the first stage and before the second stage is performed.
3. The apparatus of claim 1 , wherein the module is to change the state of each of the first and second memory cells from a state corresponding a negative threshold voltage value to a state corresponding a positive threshold voltage value.
4. The apparatus of claim 2 , wherein the state of each of the first and second memory cells includes an erase state before the first stage is performed.
5. The apparatus of claim 1 , wherein the module is to:
determine, during a first time interval of the second stage, whether the first memory cell reaches the target state; and
determine, during a second time interval of the second stage, whether the second memory cell reach the target state.
6. The apparatus of claim 5 , wherein the module is to:
apply, during the first time interval and the second time interval, a program verify voltage to the access line coupled to the first and second memory cells; and
keep a value of the program verify voltage unchanged between the first and second time intervals.
7. The apparatus of claim 1 , further comprising:
a first buffer coupled to the data line through a transistor; and
a second buffer coupled to the data line through the transistor.
8. The apparatus of claim 7 , further comprising:
a third buffer coupled to the data line through the transistor; and
a fourth buffer coupled to the data line through the transistor.
9. The apparatus of claim 1 , wherein each of the first and second memory cells is configured as a single level cell, and the target state corresponds to a value of a single bit of data.
10. The apparatus of claim 1 , wherein each of the first and second memory cells is configured as a multi-level cell, and the target state corresponds to a value of one bit among the multiple bits to be stored in each of the first and second memory cells.
11. An apparatus comprising:
a data line;
a first memory cell string coupled to the data line, the first memory cell string including a first memory cell;
a second memory cell string coupled to the data line, the second memory cell string including a second memory cell;
an access line shared by the first and second memory cells; and
a module to:
apply a first voltage to the access line during a first time interval of an operation to program a first memory cell;
apply the first voltage to the access line during a second time interval of the operation to program the second memory cell; and
apply a second voltage to the access line during a third time interval and a fourth time interval of the operation after the second time interval to determine whether the first and second memory cells reach a target threshold voltage.
12. The apparatus of claim 11 , wherein the module is to apply a third voltage to the access line during a time interval between the first and second the time intervals, wherein a value of the third voltage is less than a value of the first voltage.
13. The apparatus of claim 12 , wherein the value of the third voltage is zero.
14. The apparatus of claim 12 , wherein the value of the third voltage is greater than zero.
15. The apparatus of claim 11 , wherein the module is to:
couple the data line to a first page buffer during the third time interval to determine whether the first memory cell reaches the target threshold voltage based on information provided from the data line to the first page buffer during the third time interval; and
couple the data line to a second page buffer during the fourth time interval to determine whether the second memory cell reaches the target threshold voltage based on information provided from the data line to the second page buffer during the fourth time interval.
16. An apparatus comprising:
a data line;
a first memory cell string coupled to the data line, the first memory cell string including a first memory cell;
a second memory cell string coupled to the data line, the second memory cell string including a second memory cell;
an access line shared by the first and second memory cells; and
a module to sequentially store information in the first and second memory cells during a first time interval, and to sequentially verify during a second time interval after the first time interval whether the first and second memory cells reach their respective target states.
17. The apparatus of claim 16 , further comprising:
a first buffer coupled to the data line to contain information associated with a state of the first memory cell after the first memory cell is programmed; and
a second buffer coupled to the data line to contain information associated with a state of the second memory cell after the second memory cell is programmed.
18. The apparatus of claim 16 , wherein the module is to:
apply a program verify voltage to the access line during the second time interval; and
keep a value of the program verify voltage unchanged during the second time interval.
19. The apparatus of claim 16 , further comprising:
a third memory cell string coupled to the data line, the third memory cell string including a third memory cell;
a fourth memory cell string coupled to the data line, the fourth memory cell string including a fourth memory cell, wherein:
the access line is shared by the first, second, third, and fourth memory cells; and
the module is to sequentially store information in the first, second, third, and fourth memory cells during the first time interval, and to sequentially verify during the second time interval whether the first, second, third, and fourth memory cells reach their respective target states.
20. The apparatus of claim 19 , further comprising:
a first buffer coupled to the data line to contain information associated with a state of the first memory cell after the first memory cell is programmed;
a second buffer coupled to the data line to contain information associated with a state of the second memory cell after the second memory cell is programmed;
a third buffer coupled to the data line to contain information associated with a state of the third memory cell after the third memory cell is programmed; and
a fourth buffer coupled to the data line to contain information associated with a state of the fourth memory cell after the fourth memory cell is programmed.