Memory devices having vertical transistors and stacked storage units and methods for forming the same
In certain aspects, a memory device includes a vertical transistor including a semiconductor body extending in a first direction, a stack structure including interleaved dielectric layers and conductive layers each extending perpendicularly to the first direction, an electrode layer including a conductive material and coupled to a first end of the semiconductor body, and a storage layer over the electrode layer. The electrode layer and the storage layer extend in the first direction through the stack structure.
1. A memory device, comprising:
a vertical transistor comprising a semiconductor body extending in a first direction;
a stack structure comprising interleaved dielectric layers and conductive layers each extending perpendicularly to the first direction;
an electrode layer comprising a conductive material and coupled to a first end of the semiconductor body; and
a storage layer over the electrode layer,
wherein the electrode layer and the storage layer extend in the first direction through the stack structure, the storage layer being in contact with each conductive layer of the stack structure arranged in the first direction.
2. The memory device of claim 1 , wherein each of the conductive layers comprises a plate line and a first electrode in contact with the storage layer.
3. The memory device of claim 2 , wherein
the electrode layer comprises a plurality of second electrodes;
the storage layer comprises a plurality of storage sections; and
the first electrodes, the second electrodes, and the storage sections form a plurality of storage units stacked in the first direction.
4. The memory device of claim 3 , wherein
the electrode layer couples each of the storage units to the vertical transistor; and
each of the storage units is coupled to a respective one of the plate lines.
5. The memory device of claim 1 , wherein edges of the dielectric layers and the conductive layers define a staircase structure.
6. The memory device of claim 5 , further comprising a plurality of contacts in contact with the conductive layers, respectively, at the staircase structure.
7. The memory device of claim 1 , wherein the storage layer comprises a ferroelectric material, and the electrode layer comprises a metal.
8. The memory device of claim 1 , further comprising:
a bit line coupled to a second end opposite to the first end of the semiconductor body and extending in a second direction perpendicular to the first direction; and
a word line extending in a third direction perpendicular to the first and second directions,
wherein the vertical transistor further comprises a gate structure between the word line and the semiconductor body in the third direction.
9. The memory device of claim 8 , wherein the word line is between the stack structure and the bit line in the first direction.
10. The memory device of claim 8 , wherein the semiconductor body comprises a source and a drain at the first and second ends of the semiconductor body.
11. The memory device of claim 1 , wherein each of the electrode layer and the storage layer is a continuous layer.
12. The memory device of claim 1 , wherein the storage layer surrounds the electrode layer, and in a word-line direction, the electrode layer is sandwiched within the storage layer.
13. The memory device of claim 1 , further comprising:
a bit line coupled with the vertical transistor and extending in a second direction perpendicular to the first direction.
14. The memory device of claim 1 , wherein
in a word-line direction, a first conductive layer of the conductive layers has a shorter length than a second conductive layer of the conductive layers, the second conductive layer being closer to the vertical transistor than the first conductive layer.
15. The memory device of claim 1 , wherein
the semiconductor body is further coupled to a body line at a second end of the semiconductor body.
16. The memory device of claim 1 , further comprising:
a body line coupled to the vertical transistor and configured to enable depletion of charges from the vertical transistor.
17. A memory device, comprising:
vertical transistors each comprising a semiconductor body extending in a first direction;
storage units comprising a stack structure that comprises interleaved dielectric layers and conductive layers each extending perpendicularly to the first direction,
wherein
the storage units further comprises electrode layers each extending in the first direction through the stack structure and each coupled to a first end of a corresponding semiconductor body of the vertical transistors, and storage layers each surrounding a corresponding one of the electrode layers; and
the vertical transistors are arranged between the storage units and bit lines in the first direction.
18. The memory device of claim 17 , wherein
a portion of the storage units is coupled to one of the vertical transistors; and
the portion of the storage units is stacked in the first direction.
19. The memory device of claim 18 , wherein
a number of the portion of the storage units is determined by a number of the conductive layers in the stack structure.
20. The memory device of claim 17 , wherein
one of the storage layers surrounds a corresponding one of the electrode layers, and in a word-line direction, the one of the electrode layers is sandwiched within the corresponding one of the storage layers.