Thin film transistor, method of fabricating the same, and organic light emitting diode display device including the thin film transistor

1. A thin film transistor (TFT) comprising:

a substrate;

a polycrystalline silicon (poly-Si) semiconductor layer disposed on the substrate, comprising:

a source region,

a drain region,

a channel region,

a crystallization-inducing metal,

a first gettering site disposed in the drain region and a first gettering site disposed in the source region, and

a second gettering site spaced apart from the first gettering sites;

a gate insulating layer disposed on the semiconductor layer;

a gate electrode disposed on the gate insulating layer;

an interlayer insulating layer disposed on the gate electrode; and

source and drain electrodes disposed on the interlayer insulating layer and electrically connected to the source and drain regions of the semiconductor layer.

2. The TFT according to claim 1 , wherein the second gettering site is disposed in the drain region of the semiconductor layer.

3. The TFT according to claim 2 , wherein the second gettering site is disposed within about 0.5 to 10 μm of an interface between the channel region and the drain region.

4. The TFT according to claim 1 , wherein the semiconductor layer comprises at least two of the second gettering sites.

5. The TFT according to claim 1 , wherein the gate insulating layer and the interlayer insulating layer comprise:

first holes exposing the first gettering sites; and

a second hole exposing the second gettering site.

6. The TFT according to claim 5 , wherein the source and drain electrodes are respectively connected to the source and drain regions of the semiconductor layer, through the first holes.

7. The TFT according to claim 1 , wherein the first and second gettering sites each comprises a lattice damage region or a gettering impurity.

8. The TFT according to claim 1 , wherein each of the first and second gettering sites comprises a metallic material having a lower diffusion coefficient than the crystallization-inducing metal, the metallic material being diffused into the surface of the semiconductor layer to a predetermined depth.

9. The TFT according to claim 8 , wherein the diffusion coefficient of the metallic material is less than about 1/100 of the diffusion coefficient of the crystallization-inducing metal.

10. The TFT according to claim 9 , wherein the metallic material comprises one selected from the group consisting of Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Ru, Os, Co, Rh, Ir, Pt, Y, La, Ce, Pr, Nd, Dy, Ho, an alloy thereof, and a silicide thereof.

11. The TFT according to claim 1 , wherein the semiconductor layer comprises:

a plurality of the source, drain, and channel regions; and

a plurality of the second gettering sites disposed between the channel regions.

12. The TFT according to claim 11 , wherein:

the semiconductor layer comprises body units intersecting the gate electrode; and at least one connection portion connecting adjacent first edges of the body units; and

the first gettering sites are disposed on second edges of the body units, which are not connected by the connection unit.

13. The TFT according to claim 11 , wherein the second gettering sites are disposed closer to the drain regions than to the source regions.

14. The TFT according to claim 13 , wherein the second gettering sites are each disposed within about 0.5 to 10 .mu.m of an interface between one of the channel regions and the one of drain regions.

15. The TFT according to claim 1 , wherein the second gettering site is disposed between the first gettering sites.

16. An organic light emitting diode (OLED) display device comprising:

a substrate;

a poly-Si layer semiconductor layer disposed on the substrate, comprising:

a source region,

a drain region,

a channel region,

a crystallization-inducing metal,

a first gettering site disposed in the drain region and a first gettering site disposed in the source region, and

a second gettering site spaced apart from the first gettering sites;

a gate insulating layer disposed on the semiconductor layer;

a gate electrode disposed on the gate insulating layer;

an interlayer insulating layer disposed on the gate electrode;

source and drain electrodes disposed on the interlayer insulating layer and electrically connected to the source and drain regions of the semiconductor layer, respectively;

a first electrode electrically connected to one of the source and drain electrodes;

an organic layer disposed on the first electrode and including an emission layer (EML); and

a second electrode disposed on the organic layer.

17. The OLED display device according to claim 16 , wherein the second gettering site is disposed in the drain region of the semiconductor layer.

18. The OLED display device according to claim 17 , wherein the second gettering site is disposed within 0.5 to 10 μm of an interface between the channel region and the drain region.

19. The OLED display device according to claim 16 , wherein the second gettering site is disposed between the first gettering sites.

20. The TFT according to claim 19 , wherein each of the first and second gettering sites is configured to trap the crystallization-inducing metal which diffuses thereinto.

21. The OLED display device according to claim 16 , wherein each of the first and second gettering sites comprises a metallic material having a lower diffusion coefficient than the crystallization-inducing metal, the metallic material being diffused into the surface of the semiconductor layer to a predetermined depth.

22. The OLED display device according to claim 21 , wherein each of the first and second gettering sites is configured to trap the crystallization-inducing metal which diffuses thereinto.