Thin-film transistor and display device using oxide semiconductor

• US 7,923,723 B2
• Filed: 02/23/2007
• Issued: 04/12/2011
• Est. Priority Date: 03/17/2006
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Hayashi, Ryo, Sano, Masafumi, Abe, Katsumi
• Primary Examiner(s): Mandala; Victor
• Assistant Examiner(s): Moore; Whitney
• Application Number:
  US12/281,783
• Publication Number:
  US 20090072232A1
• Time in Patent Office: 1,509 Days
• Field of Search: 257/43, 257/57, 257/59, 257/72, 257/197, 257/83, 257/89, 257/635, 257/347, 257351-354, 257/E21.32, 257/E29.006, 257/E29.296
• US Class Current: 257/43
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 21/28202 in a nitrogen-containing ambient, e.g. nitride deposition, growth, oxynitridation, NH3 nitridation, N2O oxidation, thermal nitridation, RTN, plasma nitridation, RPN
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/518 the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• 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 thin-film transistor of the present invention has at least a semiconductor layer including: on a substrate, a source electrode, a drain electrode, and a channel region; a gate insulating film; and a gate electrode, wherein the semiconductor layer is an oxide semiconductor layer, and wherein the gate insulating film is amorphous silicon including at least O and N, and the gate insulating film has a distribution of an oxygen concentration in a thickness direction so that the oxygen concentration is high in the side of an interface with an oxide semiconductor layer and the oxygen concentration decreases toward the side of the gate electrode.

Claims

1. A thin-film transistor comprising, on a substrate:

a semiconductor layer including a channel region and being electrically connected to a source electrode and a drain electrode;

a gate insulating film; and

a gate electrode,

wherein the semiconductor layer is an amorphous oxide semiconductor layer,

wherein the gate insulating film is a single layer of amorphous silicon oxynitride, and

wherein the gate insulating film has an oxygen concentration that varies in a thickness direction, so that the oxygen concentration is relatively high at a side of an interface with the amorphous oxide semiconductor layer, continuously decreases in the thickness direction, and is relatively low at a side of an interface with the gate electrode.

2. The thin-film transistor according to claim 1, wherein the amorphous oxide semiconductor layer includes In, Zn, and O.

3. The thin-film transistor according to claim 2, wherein the amorphous oxide semiconductor layer further includes at least one element selected from a group consisting of Ga, Al, Fe, Sn, Mg, Ca, Si, and Ge, and has a resistance value less than 10¹⁰ Ω

·

m.

4. A thin-film transistor according to claim 1,

wherein the thin-film transistor incorporated in a display device that includes a display element, the display element being disposed on the substrate with the thin-film transistor, and

wherein the source electrode or the drain electrode of the thin-film transistor is connected to an electrode of the display element.

5. The thin-film transistor according to claim 4, wherein the display element is an electroluminescence element.

6. The thin-film transistor according to claim 4, wherein the display element is a liquid crystal cell.

7. The thin-film transistor according to claim 4, wherein a plurality of display elements and a plurality of thin-film transistors are two-dimensionally arranged on the substrate.

8. A thin-film transistor according to claim 2,

wherein the thin-film transistor incorporated in a display device that includes a display element, the display element being disposed on the substrate with the thin-film transistor, and

wherein the source electrode or the drain electrode of the thin-film transistor is connected to an electrode of the display element.

9. A thin-film transistor according to claim 3,

wherein the thin-film transistor incorporated in a display device that includes a display element, the display element being disposed on the substrate with the thin-film transistor, and

wherein the source electrode or the drain electrode of the thin-film transistor is connected to an electrode of the display element.

10. The thin-film transistor according to claim 8, wherein the display element is an electroluminescence element.

11. The thin-film transistor according to claim 9, wherein the display element is an electroluminescence element.

12. The thin-film transistor according to claim 8, wherein the display element is a liquid crystal cell.

13. The thin-film transistor according to claim 9, wherein the display element is a liquid crystal cell.

14. The thin-film transistor according to claim 5, wherein a plurality of display elements and a plurality of thin-film transistors are two-dimensionally arranged on the substrate.

15. The thin-film transistor according to claim 6, wherein a plurality of display elements and a plurality of thin-film transistors are two-dimensionally arranged on the substrate.

16. The thin film transistor according to claim 1, wherein the amorphous oxide semiconductor layer is an amorphous In—

Ga—

Zn oxide semiconductor layer.

17. The thin film transistor according to claim 16, wherein the amorphous In—

Ga—

Zn oxide semiconductor layer further includes at least one element selected from a group consisting of Al, Fe, Sn, Mg, Ca, Si and Ge, and has a resistance value less than 10¹⁰ Ω

·

m.

18. A thin-film transistor comprising, on a substrate:

a semiconductor layer including a channel region and being electrically connected to a source electrode and a drain electrode;

a gate insulating film; and

a gate electrode,

wherein the semiconductor layer is an amorphous oxide semiconductor layer,

wherein the gate insulating film is a single layer of amorphous silicon oxynitride,

wherein the gate insulating film has an oxygen concentration that varies in a thickness direction, so that the oxygen concentration is relatively high at a side of an interface with the amorphous oxide semiconductor layer, decreases gradually in the thickness direction, and is relatively low at a side of an interface with the gate electrode, and

wherein the relatively high oxygen concentration of the gate insulating film at the side of the interface with the amorphous oxide semiconductor layer minimizes movement of oxygen through the interface between the gate insulating film and the amorphous oxide semiconductor layer.

19. A thin-film transistor comprising, on a substrate:

a semiconductor layer including a channel region and being electrically connected to a source electrode and a drain electrode;

a gate insulating film; and

a gate electrode,

wherein the semiconductor layer is an amorphous oxide semiconductor layer,

wherein the gate insulating film is a single layer of amorphous silicon oxynitride, and

wherein the gate insulating film has a gradient distribution of an oxygen concentration in a thickness direction, so that the oxygen concentration is relatively high at a side of an interface with the amorphous oxide semiconductor layer, and so that the oxygen concentration continuously decreases toward a side of an interface with the gate electrode.

20. The thin film transistor according to claim 19, wherein the gradient distribution has a constant slope.

21. The thin film transistor according to claim 19, wherein the gradient distribution has a gradually changing slope.