Thin film transistors using thin film semiconductor materials

• US 7,994,508 B2
• Filed: 08/01/2008
• Issued: 08/09/2011
• Est. Priority Date: 08/02/2007
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Ye, Yan
• Primary Examiner(s): Landau; Matthew C
• Assistant Examiner(s): Nicely; Joseph C
• Application Number:
  US12/184,914
• Publication Number:
  US 20090050884A1
• Time in Patent Office: 1,103 Days
• Field of Search: 257/43, 257/104, 257/149, 257/151, 257/158, 257/159, 257/162, 257/291, 257/E21.411, 257/E21.459, 257/E29.273, 257/E29.296, 257/55, 257/63, 257/347, 438/149, 438/151, 438/158, 438/164
• US Class Current: 257/63
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• 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 generally comprises TFTs having semiconductor material comprising oxygen, nitrogen, and one or more element selected from the group consisting of zinc, tin, gallium, cadmium, and indium as the active channel. The semiconductor material may be used in bottom gate TFTs, top gate TFTs, and other types of TFTs. The TFTs may be patterned by etching to create both the channel and the metal electrodes. Then, the source-drain electrodes may be defined by dry etching using the semiconductor material as an etch stop layer. The active layer carrier concentration, mobility, and interface with other layers of the TFT can be tuned to predetermined values. The tuning may be accomplished by changing the nitrogen containing gas to oxygen containing gas flow ratio, annealing and/or plasma treating the deposited semiconductor film, or changing the concentration of aluminum doping.

Claims

1. A thin film transistor, comprising:

a semiconductor layer in the transistor comprising an oxynitride compound comprising oxygen, nitrogen, and one or more elements selected from the group consisting of zinc, indium, tin, cadmium, gallium, and combinations thereof.

2. The transistor of claim 1, wherein the transistor is a top gate thin film transistor.

3. The transistor of claim 1, further comprising:

a substrate;

a gate electrode disposed over the substrate;

a gate dielectric layer disposed over the gate electrode;

the semiconductor layer disposed over the gate dielectric layer; and

source and drain electrodes disposed over the semiconductor layer and spaced apart to define an active channel.

4. The transistor of claim 3, further comprising an etch stop layer disposed over the semiconductor layer in the active channel.

5. The transistor of claim 1, wherein the semiconductor layer has a mobility of greater than about 50 cm²/V-s.

6. The transistor of claim 1, wherein the oxynitride compound further comprises a dopant selected from the group consisting of Al, Ca, Si, Ti, Cu, Ge, Ni, Mn, Cr, V, Mg, and combinations thereof.

7. The transistor of claim 1, wherein the oxynitride compound comprises zinc.

8. The transistor of claim 7, wherein the oxynitride compound comprises aluminum dopant.

9. The transistor of claim 1, wherein the oxynitride compound comprises zinc, gallium, and indium.

10. The transistor of claim 9, wherein the oxynitride compound comprises aluminum dopant.

11. The transistor of claim 1, wherein the semiconductor layer additionally comprises a metal nitride.

12. The transistor of claim 11, wherein the semiconductor layer additionally comprises a metal oxide.

13. A thin film transistor, comprising:

a semiconductor layer comprising an oxynitride compound that comprises zinc, oxygen and nitrogen, the semiconductor layer additionally comprising a metal nitride, a metal oxide or combinations thereof.

14. The transistor of claim 13, wherein the oxynitride compound further comprises a dopant.

15. The transistor of claim 14, wherein the dopant comprises aluminum.

16. A thin film transistor, comprising:

a semiconductor layer comprising an oxynitride compound that comprises oxygen, nitrogen, indium, gallium and zinc, the semiconductor layer additionally comprising a metal nitride, a metal oxide or combinations thereof.