Semiconductor device

• US 8,530,892 B2
• Filed: 11/02/2010
• Issued: 09/10/2013
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: iHeartMedia Management Services, Inc. (iHeartMedia, Inc.)
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Hiraishi, Suzunosuke, Akimoto, Kengo, Sakata, Junichiro
• Primary Examiner(s): Lee, Calvin
• Application Number:
  US12/917,569
• Publication Number:
  US 20110108834A1
• Time in Patent Office: 1,043 Days
• Field of Search: 257/43, 257/215, 257/291, 257/442, 257/613, 438/104, 438/613
• US Class Current: 257/43
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• 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

An object is, in a thin film transistor including an oxide semiconductor layer, to reduce contact resistance between the oxide semiconductor layer and source and drain electrode layers electrically connected to the oxide semiconductor layer. The source and drain electrode layers have a stacked-layer structure of two or more layers in which a layer in contact with the oxide semiconductor layer is formed using an oxide of a metal whose work function is lower than the work function of the oxide semiconductor layer or an oxide of an alloy containing such a metal. Layers other than the layer in contact with the oxide semiconductor layer of the source and drain electrode layers are formed using an element selected from Al, Cr, Cu, Ta, Ti, Mo, or W, an alloy containing any of these elements as a component, an alloy containing any of these elements in combination, or the like.

Claims

1. A semiconductor device comprising:

an oxide semiconductor layer;

a source electrode layer comprising a first mixed layer; and

a drain electrode layer comprising a second mixed layer,

wherein each of the first mixed layer and the second mixed layer comprises an oxide of a first metal having a lower work function than the oxide semiconductor layer, or an oxide of an alloy comprising such a metal,

wherein each of the first mixed layer and the second mixed layer further comprises a second metal, and

wherein a first region of each of the first mixed layer and the second mixed layer that is in contact with the oxide semiconductor layer has a larger concentration of the oxide of the first metal or the oxide of the alloy than a second region of each of the first mixed layer and the second mixed layer that is not in contact with the oxide semiconductor layer.

2. The semiconductor device according to claim 1,

wherein the oxide of the first metal is indium oxide, and

wherein the oxide semiconductor layer comprises indium oxide.

3. The semiconductor device according to claim 1,

wherein the oxide of the first metal is zinc oxide, and

wherein the oxide semiconductor layer comprises zinc oxide.

4. The semiconductor device according to claim 1, wherein the oxide of the first metal is yttrium oxide.

5. The semiconductor device according to claim 1,

wherein the oxide of the first metal is titanium oxide, and

wherein the oxide semiconductor layer comprises indium oxide.

6. The semiconductor device according to claim 1,

wherein the oxide of the first metal is titanium oxide, and

wherein the second metal is titanium.

7. A semiconductor device comprising:

an oxide semiconductor layer;

a source electrode layer comprising a first mixed layer; and

a drain electrode layer comprising a second mixed layer,

wherein each of the first mixed layer and the second mixed layer comprises an oxide of a first metal having a lower work function than the oxide semiconductor layer, or an oxide of an alloy comprising such a metal,

wherein each of the first mixed layer and the second mixed layer further comprises a second metal having high heat resistance, and

wherein a first region of each of the first mixed layer and the second mixed layer that is in contact with the oxide semiconductor layer has a larger concentration of the oxide of the first metal or the oxide of the alloy than a second region of each of the first mixed layer and the second mixed layer that is not in contact with the oxide semiconductor layer.

8. The semiconductor device according to claim 7,

wherein the oxide of the first metal is indium oxide, and

wherein the oxide semiconductor layer comprises indium oxide.

9. The semiconductor device according to claim 7,

wherein the oxide of the first metal is zinc oxide, and

wherein the oxide semiconductor layer comprises zinc oxide.

10. The semiconductor device according to claim 7, wherein the oxide of the first metal is yttrium oxide.

11. The semiconductor device according to claim 7,

wherein the oxide of the first metal is titanium oxide, and

wherein the oxide semiconductor layer comprises indium oxide.

12. The semiconductor device according to claim 7,

wherein the oxide of the first metal is indium oxide, and

wherein the second metal is tungsten.

13. A semiconductor device comprising:

an oxide semiconductor layer;

a source electrode layer comprising a first mixed layer; and

a drain electrode layer comprising a second mixed layer,

wherein each of the first mixed layer and the second mixed layer comprises an oxide of a first metal having a work function lower than an electron affinity of the oxide semiconductor layer, or an oxide of an alloy comprising such a metal,

wherein each of the first mixed layer and the second mixed layer further comprises a second metal having high heat resistance, and

wherein a first region of each of the first mixed layer and the second mixed layer that is in contact with the oxide semiconductor layer has a larger concentration of the oxide of the first metal or the oxide of the alloy than a second region of each of the first mixed layer and the second mixed layer that is not in contact with the oxide semiconductor layer.

14. The semiconductor device according to claim 13,

wherein the oxide of the first metal is indium oxide, and

wherein the oxide semiconductor layer comprises indium oxide.

15. The semiconductor device according to claim 13,

wherein the oxide of the first metal is zinc oxide, and

wherein the oxide semiconductor layer comprises zinc oxide.

16. The semiconductor device according to claim 13, wherein the oxide of the first metal is yttrium oxide.

17. The semiconductor device according to claim 13,

wherein the oxide of the first metal is titanium oxide, and

wherein the oxide semiconductor layer comprises indium oxide.

18. The semiconductor device according to claim 13,

wherein the oxide of the first metal is indium oxide, and

wherein the second metal is tungsten.

19. A semiconductor device comprising:

an oxide semiconductor layer;

a source electrode layer comprising a first mixed layer; and

a drain electrode layer comprising a second mixed layer,

wherein each of the first mixed layer and the second mixed layer comprises an oxide of a first metal having a work function lower than an electron affinity of the oxide semiconductor layer, or an oxide of an alloy comprising such a metal,

wherein each of the first mixed layer and the second mixed layer further comprises a second metal, and

wherein a first region of each of the first mixed layer and the second mixed layer that is in contact with the oxide semiconductor layer has a larger concentration of the oxide of the first metal or the oxide of the alloy than a second region of each of the first mixed layer and the second mixed layer that is not in contact with the oxide semiconductor layer.

20. The semiconductor device according to claim 19,

wherein the oxide of the first metal is indium oxide, and

wherein the oxide semiconductor layer comprises indium oxide.

21. The semiconductor device according to claim 19,

wherein the oxide of the first metal is zinc oxide, and

wherein the oxide semiconductor layer comprises zinc oxide.

22. The semiconductor device according to claim 19, wherein the oxide of the first metal is yttrium oxide.

23. The semiconductor device according to claim 19,

wherein the oxide of the first metal is titanium oxide, and

wherein the oxide semiconductor layer comprises indium oxide.

24. The semiconductor device according to claim 19,

wherein the oxide of the first metal is titanium oxide, and

wherein the second metal is titanium.