Novel conductive elements for thin film transistors used in a flat panel display

• US 20050072973A1
• Filed: 01/29/2004
• Published: 04/07/2005
• Est. Priority Date: 03/12/2003
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung SDI Company Limited
• Inventors: Kim, Tae-Sung
• Granted Patent: US 7,317,206 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT

Abstract

Provided is a structure for conductive members in a TFT display. The structure is aluminum based and is heat treated. When heat treated, no hillocks are formed because of the presence of a titanium layer. Furthermore, TiAl₃ is not formed because of the presence of a TiN diffusion layer between the aluminum and the Ti layers. This novel structure has a low resistivity and is therefore suited for large displays that use thin film transistors to drive the pixels.

Claims

1. A thin film transistor, comprising a source electrode, a drain electrode, a gate electrode, and a semiconductor layer, wherein one of the source electrode, the drain electrode, and the gate electrode comprises an aluminum-based metal layer, a titanium layer, and a diffusion prevention layer interposed between the titanium and the aluminum-based layers.

2. The thin film transistor of claim 1, wherein the diffusion prevention layer and the titanium layer are orderly formed on opposite surfaces of the aluminum-based metal layer.

3. The thin film transistor of claim 1, wherein the diffusion prevention layer is a titanium nitride layer.

4. The thin film transistor of claim 3, wherein the titanium nitride layer contains 5 to 85 wt % of nitrogen.

5. The thin film transistor of claim 3, wherein the titanium nitride layer has a thickness of about 100 to 600 Å

.

6. The thin film transistor of claim 5, wherein the titanium nitride layer has a thickness of about 100 to 400 Å

.

7. The thin film transistor of claim 6, wherein the titanium nitride layer has a thickness of 200 to 400 Å

.

8. The thin film transistor of claim 7, wherein the titanium nitride layer has a thickness of about 300 Å

.

9. The thin film transistor of claim 1, wherein the aluminum-based metal layer is made of an aluminum alloy containing about 0.5 to 5 wt % of one element being selected from the group consisting of silicon, copper, neodymium, platinum, and nickel.

10. The thin film transistor of claim 9, wherein the aluminum-based metal layer is made of an aluminum-silicon alloy containing about 2 wt % of silicon.

11. A flat panel display, comprising a plurality of sub-pixels driven by thin film transistors, each of the thin film transistors comprising a source electrode, a drain electrode, a gate electrode, and a semiconductor layer, wherein at least one of the source electrode, the drain electrode, and the gate electrode comprises an aluminum-based metal layer, a titanium layer, and a diffusion prevention layer interposed between the aluminum-based metal layer and the titanium layer.

12. The flat panel display of claim 11, wherein the diffusion prevention layer and the titanium layer are orderly formed on opposite sides of the aluminum-based metal layer.

13. The flat panel display of claim 11, wherein the diffusion prevention layer is a titanium nitride layer.

14. The flat panel display of claim 13, wherein the titanium nitride layer contains 5 to 85 wt % of nitrogen.

15. The flat panel display of claim 13, wherein the titanium nitride layer has a thickness of about 100 to 600 Å

.

16. The flat panel display of claim 15, wherein the titanium nitride layer has a thickness of about 100 to 400 Å

.

17. The flat panel display of claim 16, wherein the titanium nitride layer has a thickness of 200 to 400 Å

.

18. The flat panel display of claim 17, wherein the titanium nitride layer has a thickness of about 300 Å

.

19. The flat panel display of claim 11, wherein the aluminum-based metal layer is made of an aluminum alloy containing about 0.5 to 5 wt % of one element being selected from the group consisting of silicon, copper, neodymium, platinum, and nickel.

20. The flat panel display of claim 19, wherein the aluminum-based metal layer is made of an aluminum-silicon alloy containing about 2 wt % of silicon.

21. A flat panel display, comprising:

driving circuits disposed along edges of said display;

a plurality of sub-pixels driven by thin film transistors; and

conductive lines connecting the driving circuits disposed along edges of said display to each of said plurality of sub-pixels, wherein said conductive lines comprise an aluminum-based metal layer, a titanium layer, and a diffusion prevention layer interposed between the aluminum-based metal layer and the titanium layer.

22. The flat panel display of claim 21, wherein the diffusion prevention layer and the titanium layer are orderly formed on opposite sides of the aluminum-based metal layer.

23. The flat panel display of claim 21, wherein the diffusion prevention layer is a titanium nitride layer.

24. The display of claim 23, said titanium nitride layer is 300 Å

thick.

25. The display of claim 24, said conductive lines being subjected to a heat treatment of 380°

C.

26. A process for making a flat panel display, comprising:

disposing driving circuits along edges of said display;

arranging a plurality of sub-pixels driven by thin film transistors; and

operatively connecting electrically conductive lines between the driving circuits disposed along edges of said display and each of said plurality of sub-pixels, wherein said conductive lines comprise an aluminum-based metal layer, a titanium layer, and a diffusion prevention layer interposed between the aluminum-based metal layer and the titanium layer.

27. The process of claim 26, comprised of orderly forming the diffusion prevention layer and the titanium layer on opposite sides of the aluminum-based metal layer.

28. The process of claim 26, wherein the diffusion prevention layer is a titanium nitride layer.