Semiconductor memory device with a three-dimensional stacked memory cell structure
A semiconductor memory device comprises: a semiconductor substrate; a plurality of memory units provided on the semiconductor substrate and each including a plurality of memory cells that are stacked; and a plurality of bit lines formed above each of a plurality of the memory units aligned in a column direction, an alignment pitch in a row direction of the plurality of bit lines being less than an alignment pitch in the row direction of the memory units, and an end of each of the memory units aligned in the column direction being connected to one of the plurality of bit lines formed above the plurality of the memory units aligned in the column direction.
1. A semiconductor memory device, comprising:
first, second, and third bit lines extending in a first direction, the third bit line being adjacent to the first bit line and the second bit line in a second direction, the second direction crossing the first direction;
a first memory unit including a first memory cell and a second memory cell stacked in a third direction, the third direction crossing the first direction and the second direction;
a second memory unit including a third memory cell and a fourth memory cell stacked in the third direction;
a third memory unit including a fifth memory cell and a sixth memory cell stacked in the third direction;
a first bit line contact connected to the first bit line and the first memory unit;
a second bit line contact connected to the second bit line and the second memory unit, the first bit line contact and the second bit line contact being provided along a first line crossing the third direction;
a third bit line contact connected to the third bit line and the third memory unit, the first bit line contact and the third bit line contact being provided along a second line crossing the third direction and the first line; and
a first conductive layer connected to a gate of the first memory cell, a gate of the third memory cell, and a gate of the fifth memory cell.
2. The semiconductor memory device according to claim 1 , further comprising:
a fourth bit line, the second bit line being adjacent to the fourth bit line in the second direction;
a fourth memory unit including a seventh memory cell and a eighth memory cell;
a fourth bit line contact connected to the fourth bit line and the fourth memory unit, the third bit line contact and the fourth bit line contact being provided along a third line parallel to the first line, and
the first conductive layer being connected to a gate of the seventh memory cell.
3. The semiconductor memory device according to claim 2 , wherein the first line, the second line and the third line is provided in the same plane.
4. The semiconductor memory device according to claim 1 , wherein
a first distance is provided between the first bit line contact and the second bit line contact,
a second distance is provided between the first bit line and the third bit line, and the first distance is larger than the second distance.
5. The semiconductor memory device according to claim 1 , wherein
at least one of the first to third memory units comprises: a semiconductor body extending in the third direction; and a charge storage layer provided between the semiconductor body and the first conductive layer.
6. The semiconductor memory device according to claim 1 , wherein a read or write operation is performed to the first memory cell and the fifth memory cell simultaneously.
7. The semiconductor memory device according to claim 1 , further comprising:
a sense amplifier connected selectively or simultaneously to the first bit line and the third bit line.
8. The semiconductor memory device according to claim 7 , wherein a differential type sense amplifier is used as the sense amplifier.
9. The semiconductor memory device according to claim 1 , further comprising a sense amplifier, wherein
the sense amplifier is connected electrically to the first bit line in a read or write operation and the third bit line is employed as a shield line in the read or write operation.
10. The semiconductor memory device according to claim 1 , wherein
at least one of the first to third memory units comprises: a semiconductor body including a first portion, a second portion and a third portion, the first portion and the third portion extending in the third direction, the second portion being provided between a substrate and the first portion and between a substrate and the third portion, the second portion being connected to an end of the first portion and an end of the third portion.
11. The semiconductor memory device according to claim 1 , wherein
at least one of the first to third memory units comprises: a U-shaped semiconductor body; and a charge storage layer provided between the semiconductor body and the first conductive layer.