Thin film transistor, display device having the same, and associated methods
View Patent ↗A thin film transistor (TFT), including a substrate, an active layer and a gate electrode on the substrate, and a first gate insulating layer and a second gate insulating layer between the active layer and the gate electrode. Each of the first gate insulating layer and the second gate insulating layer may have a thickness between approximately 200 Å and approximately 400 Å, inclusive.
1. A thin film transistor (TFT), comprising:
a substrate;
an active layer and a gate electrode on the substrate, the active layer including polycrystalline silicon that includes hydrogen bonds; and
a first gate insulating layer and a second gate insulating layer between the active layer and the gate electrode, the first gate insulating layer being between the active layer and the second gate insulating layer, wherein:
each of the first gate insulating layer and the second gate insulating layer has a thickness between approximately 200 Å and approximately 400 Å, inclusive, and
the thickness of the second gate insulating layer is greater than the thickness of the first gate insulating layer.
2. The TFT as claimed in claim 1 , wherein a total thickness of the first gate insulating layer and the second gate insulating layer is approximately 600 Å.
3. The TFT as claimed in claim 1 , wherein the thickness of the first gate insulating layer is approximately 200 Å, and the thickness of the second gate insulating layer is approximately 400 Å.
4. The TFT as claimed in claim 1 , wherein the first gate insulating layer includes an oxide, and the second gate insulating layer includes a silicon nitride.
5. The TFT as claimed in claim 1 , wherein the active layer has silicon crystals with an average diameter of more than approximately 10 μm.
6. A display device, comprising:
a thin film transistor (TFT); and
an organic light emitting element electrically connected to the TFT, the organic light emitting element including a first electrode, an organic emission layer, and a second electrode,
the TFT including:
a substrate,
an active layer and a gate electrode on the substrate, the active layer including polycrystalline silicon that includes hydrogen bonds, and
a first gate insulating layer and a second gate insulating layer formed between the active layer and the gate electrode, the first gate insulating layer being between the active layer and the second gate insulating layer, wherein:
each of the first gate insulating layer and the second gate insulating layer has a thickness between approximately 200 Å and approximately 400 Å, inclusive, and
the thickness of the second gate insulating layer is greater than the thickness of the first gate insulating layer.
7. The display device as claimed in claim 6 , wherein a total thickness of the first gate insulating layer and the second gate insulating layer is approximately 600 Å.
8. The display device as claimed in claim 6 , the thickness of the first gate insulating layer is approximately 200 Å, and the thickness of the second gate insulating layer is approximately 400 Å.
9. The display device as claimed in claim 6 , wherein the first gate insulating layer includes an oxide, and the second gate insulating layer includes a silicon nitride.
10. The display device as claimed in claim 6 , wherein the active layer has silicon crystals with an average diameter of more than approximately 10 μm.
11. A method of manufacturing a thin film transistor (TFT), the method comprising:
forming an active layer on a substrate;
forming a first gate insulating layer on the active layer;
forming a second gate insulating layer on the first gate insulating layer; and
forming a gate electrode on the second insulating layer, wherein:
each of the first gate insulating layer and the second gate insulating layer are formed to have a thickness between approximately 200 Å and approximately 400 Å, inclusive,
the second gate insulating layer is formed to be thicker than the first gate insulating layer, and
the active layer includes polycrystalline silicon that includes hydrogen bonds.
12. The method as claimed in claim 11 , wherein at least one of forming the first and second gate insulating layers includes an oxidation process, the method further comprising performing an annealing process after the oxidation process.
13. The method as claimed in claim 12 , wherein performing the annealing process includes performing annealing under a hydrogen gas atmosphere.
14. The method as claimed in claim 11 , wherein forming the active layer includes crystallizing an amorphous silicon using solid phase crystallization.
15. The method as claimed in claim 14 , further comprising performing a dehydrogenation process before crystallizing.
16. The method as claimed in claim 11 , wherein forming the first gate insulating layer and forming the second gate insulating layer result in a total thickness of the first gate insulating layer and the second gate insulating layer being approximately 600 Å.
17. A thin film transistor (TFT), comprising:
a substrate;
an active layer and a gate electrode on the substrate; and
a first gate insulating layer and a second gate insulating layer between the active layer and the gate electrode, the first gate insulating layer being between the active layer and the second gate insulating layer, wherein:
each of the first gate insulating layer and the second gate insulating layer has a thickness between approximately 200 Å and approximately 400 Å, inclusive, and
the active layer has silicon crystals with an average diameter of more than approximately 10 μm.
18. A display device, comprising:
a thin film transistor (TFT); and
an organic light emitting element electrically connected to the TFT, the organic light emitting element including a first electrode, an organic emission layer, and a second electrode,
the TFT including:
a substrate,
an active layer and a gate electrode on the substrate, and
a first gate insulating layer and a second gate insulating layer formed between the active layer and the gate electrode, the first gate insulating layer being between the active layer and the second gate insulating layer, wherein:
each of the first gate insulating layer and the second gate insulating layer has a thickness between approximately 200 Å and approximately 400 Å, inclusive, and
the active layer has silicon crystals with an average diameter of more than approximately 10 μm.
19. A method of manufacturing a thin film transistor (TFT), the method comprising:
forming an active layer on a substrate;
forming a first gate insulating layer on the active layer;
forming a second gate insulating layer on the first gate insulating layer; and
forming a gate electrode on the second insulating layer, wherein:
each of the first gate insulating layer and the second gate insulating layer are formed to have a thickness between approximately 200 Å and approximately 400 Å, inclusive, and
the active layer is formed to have silicon crystals with an average diameter of more than approximately 10 μm, the active layer being formed by crystallizing an amorphous silicon layer.