Semiconductor memory device and operating method thereof
A semiconductor memory device includes a memory block, a peripheral circuit, and control logic. The memory block includes dummy memory cells connected to dummy word lines and normal memory cells connected to normal word lines. The peripheral circuit performs an erase operation on the memory block. The control logic controls an operation of the peripheral circuit. The control logic controls the peripheral circuit to perform a pre-program operation on first dummy memory cells connected to first dummy word lines among the dummy word lines, in response to an erase command for the memory block, and perform a pre-program operation on second dummy memory cells connected to second dummy word lines among the dummy word lines, after the pre-program operation on the first dummy memory cells. The control logic controls the peripheral circuit to perform an erase operation on the normal memory cells.
1. A semiconductor memory device comprising:
a memory block including dummy memory cells, connected to dummy word lines, and normal memory cells, connected to normal word lines;
a peripheral circuit configured to perform an erase operation on the memory block; and
control logic configured to control an operation of the peripheral circuit, wherein the control logic is configured to control the peripheral circuit to perform:
a pre-program operation on first dummy memory cells connected to a plurality of first dummy word lines among the dummy word lines, by a single pulse program using a first program pulse, in response to an erase command for the memory block, wherein the first dummy memory cells are simultaneously pre-programmed;
a pre-program operation on second dummy memory cells connected to second dummy word lines among the dummy word lines, by the single pulse program using a second program pulse, after the pre-program operation on the first dummy memory cells; and
an erase operation on the normal memory cells,
wherein the control logic determines a level of the first program pulse based on a target threshold voltage of the first dummy memory cells and a level of the second program pulse based on a target threshold voltage of the second dummy memory cells.
2. The semiconductor memory device of claim 1 , wherein the memory block includes:
drain select transistors connected to bit lines; and
source select transistors connected to a common source line,
wherein the first dummy memory cells are located between the normal memory cells and the drain select transistors, and
wherein the second dummy memory cells are located between the normal memory cells and the source select transistors.
3. The semiconductor memory device of claim 2 , wherein, during the pre-program operation on the first dummy memory cells, the control logic controls the peripheral circuit to:
apply a ground voltage to the common source line;
apply a program pass voltage to the second dummy word lines and the normal word lines; and
apply the first program pulse to the plurality of first dummy word lines.
4. The semiconductor memory device of claim 3 , wherein, during the pre-program operation on the second dummy memory cells, the control logic controls the peripheral circuit to:
apply a ground voltage to the common source line;
apply a program pass voltage to the plurality of first dummy word lines and the normal word lines; and
apply the second program pulse to the second dummy word lines.
5. The semiconductor memory device of claim 4 , wherein the first program pulse has the same voltage magnitude as that of the second program pulse.
6. The semiconductor memory device of claim 4 , wherein the first program pulse has a higher voltage than that of the second program pulse.
7. The semiconductor memory device of claim 4 , wherein the first program pulse has a lower voltage than that of the second program pulse.
8. The semiconductor memory device of claim 1 , wherein, during the erase operation on the normal memory cells, the control logic controls the peripheral circuit to:
apply an erase inhibit voltage to the plurality of first dummy word lines and the second dummy word lines;
apply an erase allow voltage to the normal word lines; and
apply an erase voltage to a common source line.
9. The semiconductor memory device of claim 1 , wherein, during the erase operation on the normal memory cells, the control logic controls the peripheral circuit to:
float the plurality of first dummy word lines and the second dummy word lines;
apply an erase allow voltage to the normal word lines; and
apply an erase voltage to a common source line.
10. The semiconductor memory device of claim 1 , wherein the control logic controls the peripheral circuit to perform a pre-program operation on third dummy memory cells connected to third dummy word lines among the dummy word lines, after the pre-program operation on the second dummy memory cells is performed.
11. The semiconductor memory device of claim 10 , wherein the memory block includes:
drain select transistors connected to bit lines; and
source select transistors connected to a common source line,
wherein the first dummy memory cells are located between the normal memory cells and the drain select transistors,
wherein the second dummy memory cells are located between the normal memory cells, and
wherein the third memory cells are located between the normal memory cells and the source select transistors.
12. A method for operating a semiconductor memory device including a plurality of memory blocks each including first dummy memory cells, connected to a plurality of first dummy word lines, second dummy memory cells, connected to a second dummy word line, and normal memory cells, connected to normal word lines, the method comprising:
receiving an erase command;
determining a level of a first program pulse based on a target threshold voltage of the first dummy memory cells;
pre-programming first dummy memory cells included in a selected memory block, of the plurality of memory blocks, corresponding to the erase command among the plurality of memory blocks by a single pulse program using the first program pulse, wherein the first dummy memory cells included in the selected memory block are simultaneously pre-programmed;
determining a level of a second program pulse based on a target threshold voltage of the second dummy memory cells;
pre-programming second dummy memory cells included in the selected memory block by the single pulse program using the second program pulse after pre-programming the first dummy memory cells in the selected memory block; and
erasing normal memory cells included in the selected memory block.
13. The method of claim 12 , wherein the pre-programming of the first dummy memory cells included in the selected memory block includes:
applying a ground voltage to a common source line connected to the selected memory block;
applying a program pass voltage to the second dummy word line and the normal word lines connected to the selected memory block; and
applying the first program pulse to the plurality of first dummy word lines connected to the selected memory block.
14. The method of claim 13 , wherein the pre-programming of the second dummy memory cells included in the selected memory block includes:
applying a ground voltage to the common source line connected to the selected memory block;
applying a program pass voltage to the plurality of first dummy word lines and the normal word lines connected to the selected memory block; and
applying the second program pulse to the second dummy word line connected to the selected memory block.
15. The method of claim 14 , wherein:
the first dummy memory cells are drain-side dummy memory cells; and
the second dummy memory cells are source-side dummy memory cells.
16. The method of claim 14 , wherein:
the first dummy memory cells are source-side dummy memory cells; and
the second dummy memory cells are drain-side dummy memory cells.
17. The method of claim 12 , wherein the erasing of the normal memory cells included in the selected memory block includes:
applying an erase allow voltage to the normal word lines connected to the selected memory block and applying an erase inhibit voltage to the plurality of first dummy word lines and the second dummy word line connected to the selected memory block; and
applying an erase voltage to a common source line.
18. The method of claim 12 , wherein the erasing of the normal memory cells included in the selected memory block includes:
applying an erase allow voltage to the normal word lines connected to the selected memory block and floating the plurality of first dummy word lines and the second dummy word line connected to the selected memory block; and
applying an erase voltage to a common source line.
19. The method of claim 12 , wherein the selected memory block further includes third dummy memory cells connected to a third dummy word line, and
wherein the method further comprises pre-programming the third dummy memory cells, after pre-programming the second dummy memory cells included in the selected memory block and before erasing the normal memory cells included in the selected memory block.
20. The method of claim 19 , wherein:
the first dummy memory cells are drain-side dummy memory cells;
the second dummy memory cells are dummy memory cells located between the normal memory cells; and
the third dummy memory cells are source-side dummy memory cells.