Dual gate control for trench shaped thin film transistors
Disclosed herein are dual gate trench shaped thin film transistors and related methods and devices. Exemplary thin film transistor structures include a non-planar semiconductor material layer having a first portion extending laterally over a first gate dielectric layer, which is over a first gate electrode structure, and a second portion extending along a trench over the first gate dielectric layer, a second gate electrode structure at least partially within the trench, and a second gate dielectric layer between the second gate electrode structure and the first portion.
1. A thin film transistor structure comprising:
a non-planar layer having a first portion over a first gate dielectric layer and a second portion conformal to one or more sidewalls of a trench within a patterned layer, wherein the patterned layer is adjacent to the first gate dielectric layer and the non-planar layer comprises a semiconductor material;
a first gate electrode structure adjacent to the first gate dielectric layer and opposite the first portion of the non-planar layer;
a second gate electrode structure at least partially within the trench of the patterned layer;
a second gate dielectric layer between the second gate electrode structure and the first portion of the non-planar layer; and
a source and a drain coupled to the non-planar layer.
2. The thin film transistor structure of claim 1 , wherein the non-planar layer comprises a third portion over a first plateau of the patterned layer and a fourth portion over a second plateau of the patterned layer, wherein the first and second plateaus are each adjacent to the trench and the source and the drain are over the third and fourth portions of the non-planar layer, respectively.
3. The thin film transistor structure of claim 1 , wherein a portion of the patterned layer is on a first portion of the first gate dielectric layer and the non-planar layer is conformal to a surface of a second portion of the first gate dielectric layer within the trench.
4. The thin film transistor structure of claim 1 , wherein the second gate dielectric layer comprises a portion that extends along a sidewall of the second gate electrode structure within the trench.
5. The thin film transistor structure of claim 4 , further comprising:
a dielectric spacer layer between the second portion of the non-planar layer and the portion of the second gate dielectric layer.
6. The thin film transistor structure of claim 5 , wherein the non-planar layer comprises a third portion adjacent to the second portion, the third portion of the non-planar layer is over a plateau of the patterned layer, the source or the drain is over the third portion of the non-planar layer, and the source or the drain are not in contact with the second portion of the non-planar layer.
7. The thin film transistor structure of claim 4 , wherein the source or the drain comprises a portion between the second portion of the non-planar layer and the portion of the second gate dielectric layer.
8. The thin film transistor structure of claim 7 , wherein the portion of the source or the drain is in contact with the first and second portions of the non-planar layer.
9. The thin film transistor structure of claim 1 , wherein the non-planar layer comprises an amorphous or polycrystalline semiconductor material.
10. The thin film transistor structure of claim 1 , wherein the first and second gate electrode structures comprises different materials.
11. An integrated circuit (IC) memory device comprising:
peripheral circuitry comprising a plurality of field effect transistors (FETs), wherein individual ones of the FETs comprise a monocrystalline semiconductor channel; and
a memory cell array monolithically integrated with the peripheral circuitry, the memory cell array comprising a plurality of capacitor structures coupled to a plurality of thin film transistors (TFTs), wherein individual ones of the TFTs comprise:
a non-planar layer having a first portion over a first gate dielectric layer and a second portion conformal to one or more sidewalls of a trench of a patterned layer adjacent to the first gate dielectric layer, the non-planar layer comprising a semiconductor material;
a first gate electrode structure adjacent to the first gate dielectric layer and opposite the first portion of the non-planar layer;
a second gate electrode structure at least partially within the trench of the patterned layer;
a second gate dielectric layer between the second gate electrode structure and the first portion of the non-planar layer; and
a source and a drain coupled to the non-planar layer.
12. The IC memory device of claim 11 , wherein the non-planar layer comprises a third portion over a first plateau of the patterned layer and a fourth portion over a second plateau of the patterned layer, wherein the first and second plateaus are each adjacent to the trench and the source and the drain are over the third and fourth portions of the non-planar layer, respectively.
13. The IC memory device of claim 11 , wherein the second gate dielectric layer comprises a portion that extends along a sidewall of the second gate electrode structure within the trench, the IC memory device further comprising:
a dielectric spacer layer between the second portion of the non-planar layer and the portion of the second gate dielectric layer.
14. The IC memory device of claim 13 , wherein the non-planar layer comprises a third portion adjacent to the second portion, the third portion of the non-planar layer is over a plateau of the patterned layer, the source or the drain is over the third portion of the non-planar layer, and the source or the drain are not in contact with the second portion of the non-planar layer.
15. The IC memory device of claim 11 , wherein the second gate dielectric layer comprises a portion that extends along a sidewall of the second gate electrode structure within the trench, wherein the source or the drain comprises a portion between the second portion of the non-planar layer and the portion of the second gate dielectric layer.
16. The IC memory device of claim 15 , wherein the portion of the source or the drain is in contact with the first and second portions of the non-planar layer.