Non-linear element, display device including non-linear element, and electronic device including display device

• US 8,492,806 B2
• Filed: 10/26/2010
• Issued: 07/23/2013
• Est. Priority Date: 10/30/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Kawae, Daisuke
• Primary Examiner(s): Mandala, Michelle
• Application Number:
  US12/912,353
• Publication Number:
  US 20110101338A1
• Time in Patent Office: 1,001 Days
• Field of Search: 257/212, 257/233, 257/288, 257/292, 257/293, 257/910, 257/E29.117, 257/E29.122
• US Class Current: 257/292
• CPC Class Codes: H01L 27/0255 using diodes as protective elements
• 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 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/78642 Vertical transistors
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/861 Diodes
• CPC Class Codes: H02H 9/044 Physical layout, materials not provided for elsewhere varistors H01C7/12; spark-gaps H01T; Ovshinsky devices H10N70/00
• CPC Class Codes: Y10S 257/91 Diode arrays, e.g. diode read-only memory array

Abstract

A non-linear element, such as a diode, in which an oxide semiconductor is used and a rectification property is favorable is provided. In a thin film transistor including an oxide semiconductor in which the hydrogen concentration is less than or equal to 5×10¹⁹/cm³, the work function φms of a source electrode in contact with the oxide semiconductor, the work function φmd of a drain electrode in contact with the oxide semiconductor, and electron affinity χ of the oxide semiconductor satisfy φms≦χ<φmd. By electrically connecting a gate electrode and the drain electrode of the thin film transistor, a non-linear element with a more favorable rectification property can be achieved.

Claims

1. A non-linear element comprising:

a first electrode formed over a substrate;

an oxide semiconductor layer formed on and in contact with the first electrode, in which a hydrogen concentration is less than or equal to 5×

10¹⁹ /cm³; and

a second electrode formed on and in contact with the oxide semiconductor layer,

wherein a work function φ

ma of the first electrode, electron affinity χ

of the oxide semiconductor layer, and a work function φ

mc of the second electrode satisfy φ

mc ≦

χ

<

φ

ma.

2. The non-linear element according to claim 1, wherein a material of the first electrode is tungsten, molybdenum, chromium, iron, or indium tin oxide.

3. The non-linear element according to claim 1, wherein a material of the second electrode is titanium, yttrium, aluminum, magnesium, silver, or zirconium.

4. The non-linear element according to claim 1, wherein a difference between the work function φ

ma of the first electrode and the electron affinity χ

of the oxide semiconductor layer is greater than or equal to 0.2 eV.

5. The non-linear element according to claim 1, wherein a carrier concentration of the oxide semiconductor layer is less than or equal to 5×

10¹⁴ /cm³.

6. The non-linear element according to claim 1, further comprising an insulating film covering the first electrode, the oxide semiconductor layer, and the second electrode.

7. A display device comprising a protection circuit including the non-linear element according to claim 1.

8. An electronic device comprising the display device according to claim 7.

9. A non-linear element comprising:

a first electrode formed over a substrate;

an oxide semiconductor layer formed on and in contact with the first electrode, in which a hydrogen concentration is less than or equal to 5×

10¹⁹ /cm³;

a second electrode formed on and in contact with the oxide semiconductor layer;

an insulating film covering the first electrode, the oxide semiconductor layer, and the second electrode; and

a plurality of third electrodes formed in contact with the insulating film,

wherein a work function φ

md of the first electrode, electron affinity χ

of the oxide semiconductor layer, and a work function φ

ms of the second electrode satisfy φ

ms ≦

χ

<

φ

md.

10. The non-linear element according to claim 9, wherein a material of the first electrode is tungsten, molybdenum, chromium, iron, or indium tin oxide.

11. The non-linear element according to claim 9, wherein a material of the second electrode is titanium, yttrium, aluminum, magnesium, silver, or zirconium.

12. The non-linear element according to claim 9, wherein a difference between the work function φ

md of the first electrode and the electron affinity χ

of the oxide semiconductor layer is greater than or equal to 0.2 eV.

13. The non-linear element according to claim 9, wherein a carrier concentration of the oxide semiconductor layer is less than or equal to 5×

10¹⁴ /cm³.

14. The non-linear element according to claim 9, wherein at least a region of the insulating film which is in contact with the oxide semiconductor layer is an oxide insulating film.

15. The non-linear element according to claim 14, wherein the oxide insulating film is a silicon oxide film which is covered by silicon nitride.

16. A display device comprising a protection circuit including the non-linear element according to claim 9.

17. An electronic device comprising the display device according to claim 16.

18. A non-linear element comprising:

a first electrode formed over a substrate;

an oxide semiconductor layer formed on and in contact with the first electrode, in which a hydrogen concentration is less than or equal to 5×

10¹⁹ /cm³;

a second electrode formed on and in contact with the oxide semiconductor layer;

an insulating film covering the first electrode, the oxide semiconductor layer, and the second electrode; and

a plurality of third electrodes formed in contact with the insulating film,

wherein the plurality of third electrodes is adjacent to a side surface of the oxide semiconductor layer with the insulating film interposed therebetween,

wherein the plurality of third electrodes is electrically connected to the first electrode, and

wherein a work function φ

md of the first electrode, electron affinity χ

of the oxide semiconductor layer, and a work function φ

ms of the second electrode satisfy φ

ms ≦

χ

<

φ

md.

19. The non-linear element according to claim 18, wherein a material of the first electrode is tungsten, molybdenum, chromium, iron, or indium tin oxide.

20. The non-linear element according to claim 18, wherein a material of the second electrode is titanium, yttrium, aluminum, magnesium, silver, or zirconium.

21. The non-linear element according to claim 18, wherein a difference between the work function φ

md of the first electrode and the electron affinity χ

of the oxide semiconductor layer is greater than or equal to 0.2 eV.

22. The non-linear element according to claim 18, wherein a carrier concentration of the oxide semiconductor layer is less than or equal to 5×

10¹⁴ /cm³.

23. The non-linear element according to claim 18, wherein at least a region of the insulating film which is in contact with the oxide semiconductor layer is an oxide insulating film.

24. The non-linear element according to claim 23, wherein the oxide insulating film is a silicon oxide film which is covered by silicon nitride.

25. A display device comprising a protection circuit including the non-linear element according to claim 18.

26. An electronic device comprising the display device according to claim 25.

27. A non-linear element comprising:

a first electrode formed over a substrate;

an oxide semiconductor layer formed on and in contact with the first electrode, in which a hydrogen concentration is less than or equal to 5×

10¹⁹ /cm³;

a second electrode formed on and in contact with the oxide semiconductor layer;

an insulating film covering the first electrode, the oxide semiconductor layer, and the second electrode; and

a plurality of third electrodes formed in contact with the insulating film,

wherein the plurality of third electrodes is adjacent to a side surface of the oxide semiconductor layer with the insulating film interposed therebetween,

wherein the plurality of third electrodes is electrically connected to the second electrode, and

wherein a work function φ

md of the first electrode, electron affinity χ

of the oxide semiconductor layer, and a work function φ

ms of the second electrode satisfy φ

ms ≦

χ

<

φ

md.

28. The non-linear element according to claim 27, wherein a material of the first electrode is tungsten, molybdenum, chromium, iron, or indium tin oxide.

29. The non-linear element according to claim 27, wherein a material of the second electrode is titanium, yttrium, aluminum, magnesium, silver, or zirconium.

30. The non-linear element according to claim 27, wherein a difference between the work function φ

md of the first electrode and the electron affinity χ

of the oxide semiconductor layer is greater than or equal to 0.2 eV.

31. The non-linear element according to claim 27, wherein a carrier concentration of the oxide semiconductor layer is less than or equal to 5×

10¹⁴ /cm³.

32. The non-linear element according to claim 27, wherein at least a region of the insulating film which is in contact with the oxide semiconductor layer is an oxide insulating film.

33. The non-linear element according to claim 32, wherein the oxide insulating film is a silicon oxide film which is covered by silicon nitride.

34. A display device comprising a protection circuit including the non-linear element according to claim 27.

35. An electronic device comprising the display device according to claim 34.