PROCESS FOR MAKING THIN FILM FIELD EFFECT TRANSISTORS USING ZINC OXIDE

• US 20080020550A1
• Filed: 07/19/2006
• Published: 01/24/2008
• Est. Priority Date: 07/19/2006
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Ye, Yan, White, John M., Eaglesham, David J.
• Granted Patent: US 7,674,662 B2
• Time in Patent Office: Days
• US Class Current: 438/478
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

The present invention comprises a method of forming a zinc oxide based thin film transistor by blanket depositing the zinc oxide layer and the source-drain metal layer and then wet etching through the zinc oxide while etching through the source-drain electrode layer. Thereafter, the active channel is formed by dry etching the source-drain electrode layer without effectively etching the zinc oxide layer.

Claims

1. A method for forming a thin film transistor, comprising:

blanket depositing a zinc oxide layer over an entire substrate surface;

depositing a source-drain electrode layer over the zinc oxide layer; and

patterning the zinc oxide layer and the source-drain electrode layer simultaneously.

2. The method of claim 1, wherein the zinc oxide layer is doped with aluminum, tin, or gallium.

3. The method of claim 1, wherein the patterning further comprises:

depositing photoresist;

pattern developing the photoresist; and

etching the zinc oxide layer using the developed photoresist as a mask.

4. The method of claim 1, wherein the zinc oxide layer is not deposited using a mask.

5. The method of claim 1, wherein the substrate has a surface area of at least about 2 m².

7. The method of claim 1, wherein the etching is wet etching.

8. The method of claim 1, wherein the zinc oxide layer is deposited by sputtering.

6. The method of 1, wherein the etchant used to etch the source/drain electrode layer is the same etchant used to etch the doped zinc oxide layer.

9. A method for forming a bottom gate thin film transistor, comprising:

depositing a zinc oxide layer over a gate electrode and a gate dielectric layer;

depositing a metal containing layer over the doped zinc oxide layer;

wet etching the metal containing layer and the zinc oxide layer; and

dry etching the metal containing layer.

10. The method of claim 9, wherein the zinc oxide is doped with aluminum, tin, or gallium.

11. The method of claim 9, wherein the wet etching further comprises:

depositing photoresist;

pattern developing the photoresist; and

wet etching the zinc oxide layer using the developed photoresist as a mask.

12. The method of claim 9, wherein the zinc oxide layer is not deposited using a mask.

13. The method of claim 9, wherein the substrate has a surface area of at least about 2 m².

14. The method of claim 9, wherein the dry etching further comprises:

depositing photoresist;

pattern developing the photoresist; and

dry etching the metal containing layer using the developed photoresist as a mask, wherein the zinc oxide layer is not effectively etched.

15. The method of claim 9, wherein the zinc oxide is deposited by sputtering.

16. A method for forming a top gate thin film transistor, comprising:

depositing an underlayer a substrate;

depositing a zinc oxide layer over the underlayer;

depositing a source-drain metal layer over the zinc oxide layer; and

wet etching the source-drain metal layer and the zinc oxide layer.

17. The method of claim 16, wherein the zinc oxide is doped with aluminum, tin, or gallium.

18. The method of claim 16, wherein the wet etching further comprises:

depositing photoresist;

pattern developing the photoresist; and

wet etching the zinc oxide layer using the developed photoresist as a mask.

19. The method of claim 16, wherein the zinc oxide layer is not deposited using a mask.

20. The method of claim 16, wherein the substrate has a surface area of at least about 2 m².

21. The method of claim 16, wherein the etchant used to etch the source-drain metal layer is the same etchant used to etch the zinc oxide layer.

22. The method of claim 16, wherein the zinc oxide layer is deposited by sputtering.