Semiconductor memory device and memory system
According to one embodiment, a semiconductor memory device includes first and second memory cells, a word line, and first and second bit lines. The first and second bit lines are electrically connected to one ends of the first and second memory cells, respectively. In retry reading, a voltage applied to the first bit line is different from a voltage applied to the second bit line.
1. A method of controlling a memory device, the memory device comprising: a first word line above a semiconductor substrate; a second word line above the first word line; a first memory cell coupled to the first word line; and a second memory cell coupled to the second word line, the method comprising:
executing, for a first address corresponding to the first memory cell, a first read operation in which a first voltage is applied to the first word line;
executing, for the first address, a second read operation in which a second voltage is applied to the first word line;
executing, for the first address, a third read operation in which a third voltage is applied to the first word line;
executing, for a second address corresponding to the second memory cell, a fourth read operation in which a fourth voltage, is applied to the second word line;
executing, for the second address, a fifth read operation in which a fifth voltage, is applied to the second word line; and
executing, for the second address, a sixth read operation in which a sixth voltage is applied to the second word line, wherein
a first value difference between the fourth voltage and the fifth voltage is different from a second value difference between the fourth voltage and the sixth voltage, and
a third value difference between the first voltage and the second voltage is different from the first value difference.
2. The method according to claim 1 , wherein a fourth value difference between the first voltage and the third voltage is different from the third value difference.
3. The method according to claim 1 , wherein
the second read operation is executed after the first read operation,
the fifth read operation is executed after the fourth read operation,
the second voltage is higher than first voltage, and
the fifth voltage is higher than the fourth voltage.
4. The method according to claim 3 , wherein
the third read operation is executed after the second read operation,
the sixth read operation is executed after the fifth read operation,
the third voltage is lower than the first voltage, and
the sixth voltage is lower than the fourth voltage.
5. The method according to claim 1 , wherein the first voltage is higher than the fourth voltage.
6. The method according to claim 1 , wherein
the memory device further comprises: a third word line between the first word line and the second word line; a third memory cell coupled to the third word line; a fourth word line above the third word line; and a fourth memory cell coupled to the fourth word line,
the method further comprises:
executing, for a third address corresponding to the third memory cell, a seventh read operation in which the first voltage is applied the third word line;
executing, for the third address, an eighth read operation in which the second voltage is applied to the third word line;
executing, for the third address, a ninth read operation in which the third voltage is applied to the third word line;
executing, for a fourth address corresponding to the fourth memory cell, a tenth read operation in which the fourth voltage is applied to the fourth word line;
executing, for the fourth address, an eleventh read operation in which the fifth voltage is applied to the fourth word line; and
executing, for the fourth address, a twelfth read operation in which the sixth voltage is applied to the fourth word line.
7. The method according to claim 1 , wherein
the first memory cell and the second memory cell are connected in series between a first selection transistor and a second selection transistor and connected to the same bit line via a current path of the first selection transistor.