Thin film transistor, method of manufacturing the same, organic light emitting display apparatus comprising the thin film transistor, and method of manufacturing the same

1. A thin film transistor, comprising:

a gate electrode;

an active layer formed of an oxide and insulated from the gate electrode;

a source electrode and a drain electrode formed of an oxide on the active layer such that the source electrode and the drain electrode are insulated from the gate electrode and electrically connected to the active layer; and

the active layer, the source, and the drain electrode being formed using an atomic layer deposition (ALD) and an insitu process, and the root mean square (RMS) value of the surface roughness of the active layer which contacts with the source and drain electrodes being less than 1 nm.

2. The thin film transistor of claim 1 , with the active layer and the source and drain electrodes being formed of an oxide comprising Zinc.

3. The thin film transistor of claim 2 , with the oxide comprising one compound selected from a group consisting of ZnSnO, ZnInO, ZnInGaO and ZnSnGaO.

4. The thin film transistor of claim 1 , in which the concentration of the carrier in the active layer is in a range of 1×10 14 cm −3 to 1×10 15 cm −3 , and the concentration of the carrier in the source and drain electrodes is in a range of 1×10 16 cm −3 to 1×10 20 cm −3 .

5. An organic light emitting display apparatus, comprising:

a thin film transistor, comprising:

a gate electrode;

an active layer formed of an oxide and insulated from the gate electrode;

a source electrode and a drain electrode formed of an oxide on the active layer such that the source electrode and the drain electrode are insulated from the gate electrode and electrically connected to the active layer; and

the active layer, the source, and the drain electrode being formed using an atomic layer deposition (ALD) and an insitu process, and the root mean square (RMS) value of the surface roughness of the active layer which contacts with the source and drain electrodes being less than 1 nm; and

an organic electroluminescence device being electrically connected to the thin film transistor.

6. The thin film transistor of claim 5 , with the active layer and the source and drain electrodes being formed of an oxide comprising Zinc.

7. The thin film transistor of claim 6 , with the oxide comprising one compound selected from a group consisting of ZnSnO, ZnInO, ZnInGaO and ZnSnGaO.

8. The thin film transistor of claim 6 , in which the concentration of the carrier in the active layer is in a range of 1×10 14 cm −3 to 1×10 15 cm −3 , and the concentration of the carrier in the source and drain electrodes is in a range of 1×10 16 cm −3 to 1×10 20 cm −3 .

9. A method of manufacturing a thin film transistor, the method comprising:

forming a gate electrode on a substrate;

forming an active layer insulated from the gate electrode; and

forming a source electrode and a drain electrode using an oxide on the active layer such that the source electrode and the drain electrode are insulated from the gate electrode and electrically connected to the active layer,

wherein the active layer, the source electrode, and the drain electrodes are formed using an atomic layer deposition (ALD) and an insitu process.

10. The method of claim 9 , in which the active layer and the source and drain electrodes are formed of a ZnO-based oxide.

11. The method of claim 10 , in which the ZnO-based oxide comprises one compound selected from a group consisting of ZnSnO, ZnInO, ZnInGaO, and ZnSnGaO.

12. The method of claim 9 , in which the concentration of the carrier in the active layer is in the range of 1×10 14 cm −3 to 1×10 15 cm −3 , and the concentration of the carrier in the source and drain electrodes is in the range of 1×10 16 cm −3 to 1×10 20 cm −3 .

13. The method of claim 9 , in which a temperature of a process for forming the active layer is different from a temperature of a process for forming the source and drain electrodes.

14. The method of claim 9 , in which the temperature during the forming of the source and drain electrodes is higher than that during the forming of the active layer while the active layer and the source and drain electrode are sequentially formed using the ALD.

15. The method of claim 9 , in which the forming of the active layer and the forming of the source and drain electrodes comprises pattering simultaneously the active layer, the source electrode, and the drain electrode using a halftone mask.

16. A method of manufacturing an organic light emitting display apparatus, the method comprising:

forming a thin film transistor by forming a gate electrode on a substrate; forming an active layer insulated from the gate electrode; forming a source electrode and a drain electrode using an oxide on the active layer such that the source electrode and the drain electrode are insulated from the gate electrode and electrically connected to the active layer, with the active layer, the source electrode, and the drain electrodes being formed using an atomic layer deposition (ALD) and an insitu process; and

forming an organic electroluminescence device which is electrically connected to the thin film transistor.

17. The method of claim 16 , in which the active layer and the source and drain electrodes are formed of a ZnO-based oxide.

18. The method of claim 17 , in which the ZnO-based oxide comprises one compound selected from a group consisting of ZnSnO, ZnSnO, ZnInGaO, and ZnSnGaO.

19. The method of claim 16 , in which the concentration of the carrier in the active layer is in the range of 1×10 14 cm −3 to 1×10 15 cm −3 , and the concentration of the carrier in the source and drain electrodes is in the range of 1×10 16 cm −3 to 1×10 20 cm −3 .

20. The method of claim 16 , in which a temperature of a process for forming the active layer is different from a temperature of a process for forming the source and drain electrodes.

21. The method of claim 16 , in which the temperature during the forming of the source and drain electrodes is higher than that during the forming of the active layer while the active layer and the source and drain electrode are sequentially formed using the ALD.