NON-LINEAR ELEMENT, DISPLAY DEVICE INCLUDING NON-LINEAR ELEMENT, AND ELECTRONIC DEVICE INCLUDING DISPLAY DEVICE

• US 20110127526A1
• Filed: 11/24/2010
• Published: 06/02/2011
• Est. Priority Date: 11/27/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kawae, Daisuke, Uochi, Hideki, Yamazaki, Shunpei
• Granted Patent: US 8,390,044 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• 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 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• CPC Class Codes: H01L 29/78642 Vertical transistors
• CPC Class Codes: H01L 29/78645 with multiple gate
• CPC Class Codes: H01L 29/78648 arranged on opposing sides of the channel
• 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 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A non-linear element (such as a diode) which includes an oxide semiconductor and has a favorable rectification property is provided. In a transistor including an oxide semiconductor in which the hydrogen concentration is 5×10¹⁹/cm³ or lower, a work function φms of a source electrode in contact with the oxide semiconductor, a 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, and an area of contact between the drain electrode and the oxide semiconductor is larger than an area of contact between the source electrode and the oxide semiconductor. By electrically connecting a gate electrode and the drain electrode in the transistor, a non-linear element having a favorable rectification property can be achieved.

Claims

1. A non-linear element comprising:

a source electrode;

an oxide semiconductor layer adjacent to the source electrode;

a drain electrode adjacent to the oxide semiconductor layer, wherein the oxide semiconductor layer is interposed between the source electrode and the drain electrode so that a current flows through the oxide semiconductor layer in a thickness direction thereof;

a gate insulating layer over the source electrode, the oxide semiconductor layer, and the drain electrode; and

a plurality of gate electrodes adjacent to the oxide semiconductor layer with the gate insulating layer interposed therebetween, the plurality of gate electrodes being in contact with the gate insulating layer,

wherein the plurality of gate electrodes are electrically connected to the drain electrode; and

wherein an area of contact between the source electrode and the oxide semiconductor layer is different from an area of contact between the drain electrode and the oxide semiconductor layer.

2. The non-linear element according to claim 1, wherein the area of contact between the drain electrode and the oxide semiconductor layer is larger than the area of contact between the source electrode and the oxide semiconductor layer.

3. The non-linear element according to claim 1, wherein the area of contact between the drain electrode and the oxide semiconductor layer is less than the area of contact between the source electrode and the oxide semiconductor layer.

4. The non-linear element according to claim 1,

wherein carrier density of the oxide semiconductor layer is lower than 1×

10¹²/cm³.

5. The non-linear element according to claim 1,

wherein at least a portion of the gate insulating layer which is contact with the oxide semiconductor layer comprises an oxide insulating layer.

6. The non-linear element according to claim 1, further comprising a nitride insulating layer on and in contact with the gate insulating layer.

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;

an oxide semiconductor layer on and in contact with the first electrode;

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

a gate insulating layer over the first electrode, the oxide semiconductor layer, and the second electrode; and

a plurality of third electrodes adjacent to the oxide semiconductor layer with the gate insulating layer interposed therebetween, the plurality of third electrodes being in contact with the gate insulating layer,

wherein the plurality of third electrodes are electrically connected to one of the first electrode and the second electrode;

wherein one of the first electrode and the second electrode, which is electrically connected to the plurality of third electrodes, has a work function φ

md, the other of the first electrode and the second electrode, which is not electrically connected to the plurality of third electrodes, has a work function φ

ms, and the oxide semiconductor layer has an electron affinity χ

,

wherein the work function φ

md, the work function φ

ms and the electron affinity χ

satisfy φ

ms≦

χ

<

φ

md, and

wherein a first area of contact between the oxide semiconductor layer and the one of the first electrode and the second electrode is different from a second area of contact between the oxide semiconductor layer and the other of the first electrode and the second electrode.

10. The non-linear element according to claim 9,

wherein the first area is larger than the second area.

11. The non-linear element according to claim 9,

wherein the first area is less than the second area.

12. The non-linear element according to claim 9,

wherein carrier density of the oxide semiconductor layer is lower than 1×

10¹²/cm³.

13. The non-linear element according to claim 9,

wherein at least a portion of the gate insulating layer which is contact with the oxide semiconductor layer comprises an oxide insulating layer.

14. The non-linear element according to claim 9, further comprising a nitride insulating layer on and in contact with the gate insulating layer.

15. The non-linear element according to claim 9,

wherein the one of the first electrode and the second electrode, which has the work function φ

md, comprises an element selected from the group consisting of tungsten, molybdenum, chromium, iron, gold, platinum, copper, cobalt, nickel, beryllium, and indium tin oxide.

16. The non-linear element according to claim 9,

wherein the other of the first electrode and the second electrode, which has the work function φ

ms, comprises an element selected from the group consisting of titanium, yttrium, aluminum, zirconium, magnesium, silver, manganese, and tantalum.

17. The non-linear element according to claim 9,

wherein a material of the first electrode is different from a material of the second electrode.

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

19. An electronic device comprising the display device according to claim 18.

20. The non-linear element according to claim 9,

wherein the first electrode is formed over a substrate;

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

wherein the first electrode has the work function φ

md,

wherein the second electrode has the work function φ

ms, and

wherein an area of contact between the first electrode and the oxide semiconductor layer is larger than an area of contact between the second electrode and the oxide semiconductor layer.

21. The non-linear element according to claim 9,

wherein the oxide semiconductor layer comprises hydrogen at a concentration of 5×

10¹⁹/cm³ or less.

22. The non-linear element according to claim 21, wherein the concentration of hydrogen in the oxide semiconductor layer is detected by secondary ion mass spectrometry.

23. A non-linear element comprising:

a first electrode;

an oxide semiconductor layer on and in contact with the first electrode;

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

a gate insulating layer over the first electrode, the oxide semiconductor layer, and the second electrode; and

a third electrode adjacent to the oxide semiconductor layer with the gate insulating layer interposed therebetween, the third electrode being in contact with the gate insulating layer,

wherein the third electrode is connected to one of the first electrode and the second electrode; and

wherein a first area of contact between the oxide semiconductor layer and the one of the first electrode and the second electrode is different from a second area of contact between the oxide semiconductor layer and the other of the first electrode and the second electrode.

24. The non-linear element according to claim 23,

wherein the first area is larger than the second area.

25. The non-linear element according to claim 23,

wherein the first area is less than the second area.

26. The non-linear element according to claim 23,

wherein carrier density of the oxide semiconductor layer is lower than 1×

10¹²/cm³.

27. The non-linear element according to claim 23,

wherein at least a portion of the gate insulating layer which is contact with the oxide semiconductor layer comprises an oxide insulating layer.

28. The non-linear element according to claim 23, further comprising a nitride insulating layer on and in contact with the gate insulating layer.

29. The non-linear element according to claim 23,

wherein the one of the first electrode and the second electrode, which has a work function φ

md, comprises an element selected from the group consisting of tungsten, molybdenum, chromium, iron, gold, platinum, copper, cobalt, nickel, beryllium, and indium tin oxide.

30. The non-linear element according to claim 23,

wherein the other of the first electrode and the second electrode, which has a work function φ

ms, comprises an element selected from the group consisting of titanium, yttrium, aluminum, zirconium, magnesium, silver, manganese, and tantalum.

31. The non-linear element according to claim 23,

wherein a material of the first electrode is different from a material of the second electrode.

32. A display device comprising a protection circuit including the non-linear element according to claim 23.

33. An electronic device comprising the display device according to claim 32.