SEMICONDUCTOR DEVICE

• US 20110108833A1
• Filed: 11/02/2010
• Published: 05/12/2011
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Sakata, Junichiro, Akimoto, Kengo, Hiraishi, Suzunosuke
• Granted Patent: US 8,841,662 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02178 the material containing aluminium, e.g. Al2O3
• 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 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• 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

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 a metal whose work function is lower than the work function of the oxide semiconductor layer or 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 layer in contact with the oxide semiconductor layer; and

a drain electrode layer comprising a second layer in contact with the oxide semiconductor layer,

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

2. A semiconductor device according to claim 1, wherein each of the source electrode layer and the drain electrode layer has a stacked-layer structure.

3. The semiconductor device according to claim 1,

wherein the metal is indium, and

wherein the oxide semiconductor layer comprises indium oxide.

4. The semiconductor device according to claim 1,

wherein the metal is zinc, and

wherein the oxide semiconductor layer comprises zinc oxide.

5. The semiconductor device according to claim 1,

wherein the metal is yttrium.

6. The semiconductor device according to claim 1,

wherein the metal is titanium, and

wherein the oxide semiconductor layer comprises indium oxide.

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 a first metal having a lower work function than the oxide semiconductor layer, or 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 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 first metal or the alloy than a 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 first metal is indium, and

wherein the oxide semiconductor layer comprises indium oxide.

9. The semiconductor device according to claim 7,

wherein the first metal is zinc, and

wherein the oxide semiconductor layer comprises zinc oxide.

10. The semiconductor device according to claim 7,

wherein the first metal is yttrium.

11. The semiconductor device according to claim 7,

wherein the first metal is titanium, and

wherein the oxide semiconductor layer comprises indium oxide.

12. A semiconductor device comprising:

an oxide semiconductor layer;

a source electrode layer comprising a first layer in contact with the oxide semiconductor layer; and

a drain electrode layer comprising a second layer in contact with the oxide semiconductor layer,

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

13. A semiconductor device according to claim 12, wherein each of the source electrode layer and the drain electrode layer has a stacked-layer structure.

14. The semiconductor device according to claim 12,

wherein the metal is indium, and

wherein the oxide semiconductor layer comprises indium oxide.

15. The semiconductor device according to claim 12,

wherein the metal is zinc, and

wherein the oxide semiconductor layer comprises zinc oxide.

16. The semiconductor device according to claim 12,

wherein the metal is yttrium.

17. The semiconductor device according to claim 12,

wherein the metal is titanium, and

wherein the oxide semiconductor layer comprises indium oxide.

18. 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 a first metal having a work function lower than an electron affinity of the oxide semiconductor layer, or 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 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 first metal or the alloy than a region of each of the first mixed layer and the second mixed layer that is not in contact with the oxide semiconductor layer.

19. The semiconductor device according to claim 18,

wherein the first metal is indium, and

wherein the oxide semiconductor layer comprises indium oxide.

20. The semiconductor device according to claim 18,

wherein the first metal is zinc, and

wherein the oxide semiconductor layer comprises zinc oxide.

21. The semiconductor device according to claim 18,

wherein the first metal is yttrium.

22. The semiconductor device according to claim 18,

wherein the first metal is titanium, and

wherein the oxide semiconductor layer comprises indium oxide.