Semiconductor memory device
View Patent ↗According to one embodiment, a semiconductor memory device includes the following configuration. A second word line is provided above a first word line on a substrate. A third word line is provided above the second word line. A semiconductor layer includes a first part that passes through the first word line, a second part that passes through the second and the third word lines, and is provided above the first part, and a joint provided between the first and second parts. When a write operation is performed on a memory cell of the third word line, prior to applying a write voltage to the third word line, a first voltage is applied to a bit line, a second voltage is applied to the third word line, and a third voltage higher than the second voltage is applied to the second word line.
1. A semiconductor memory device comprising:
a first word line provided above a substrate;
a second word line provided above the first word line;
a first pillar including a first columnar portion, a second columnar portion and a joint portion, the first columnar portion being provided above the substrate, the second columnar portion being provided above the first columnar portion and passing through the first word line and the second word line, and the joint portion being provided between the first columnar portion and the second columnar portion;
a row decoder configured to apply a voltage to the first and the second word lines; and
a select transistor provided above the first pillar, wherein
in a precharge operation performed during a write operation, the row decoder is configured to apply a first voltage to the first word line and to apply a second voltage lower than the first voltage to the second word line.
2. The semiconductor memory device according to claim 1 , further comprising a third word line provided above the second word line, wherein
in the precharge operation, the row decoder is configured to apply a third voltage lower than the second voltage to the third word line.
3. The semiconductor memory device according to claim 1 , further comprising a fourth word line provided between the first word line and the joint portion, wherein
in the precharge operation, the row decoder is configured to apply a fourth voltage lower than the first voltage to the fourth word line.
4. The semiconductor memory device according to claim 1 ,
wherein the write operation includes a program operation performed after the precharge operation, and
in the program operation, the row decoder is configured to apply a program voltage to the second word line.
5. The semiconductor memory device according to claim 1 ,
wherein the first word line and the second word line are adjacent to each other via an insulating film.
6. The semiconductor memory device according to claim 1 , further comprising:
a fifth word line provided above the joint portion and adjacent to the joint portion; and
a sixth word line provided below the joint portion and adjacent to the joint portion, wherein
the first word line and the second word line are adjacent to each other via an insulating film, a distance between the first word line and the second word line is narrower than a distance between the fifth word line and the sixth word line.
7. The semiconductor memory device according to claim 1 ,
wherein, in a direction parallel to a surface of the substrate, a diameter of the joint portion is larger than a diameter of a contact portion between the first columnar portion and the joint portion and larger than a diameter of a contact portion between the second columnar portion and the joint portion.
8. The semiconductor memory device according to claim 1 ,
wherein the write operation includes a program operation performed after the precharge operation,
after the precharge operation is finished and before the program operation begins, the row decoder is configured to apply a fifth voltage to the select transistor, which turns off the select transistor.
9. The semiconductor memory device according to claim 1 ,
wherein the first pillar is a memory pillar.