SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

• US 20110012116A1
• Filed: 07/14/2010
• Published: 01/20/2011
• Est. Priority Date: 07/18/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: KUWABARA, Hideaki, MIYAKE, Hiroyuki, YAMAZAKI, Shunpei, SAKATA, Junichiro
• Granted Patent: US 8,994,024 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• 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 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 29/45 Ohmic electrodes

Abstract

A highly reliable display device which has high aperture ratio and includes a transistor with stable electrical characteristics is manufactured. The display device includes a driver circuit portion and a display portion over the same substrate. The driver circuit portion includes a driver circuit transistor and a driver circuit wiring. A source electrode and a drain electrode of the driver circuit transistor are formed using a metal. A channel layer of the driver circuit transistor is formed using an oxide semiconductor. The driver circuit wiring is formed using a metal. The display portion includes a pixel transistor and a display portion wiring. A source electrode and a drain electrode of the pixel transistor are formed using a transparent oxide conductor. A semiconductor layer of the pixel transistor is formed using the oxide semiconductor. The display portion wiring is formed using a transparent oxide conductor.

Claims

1. A semiconductor device comprising:

a pixel portion formed over a substrate, the pixel portion including a first transistor, and

a driver circuit portion formed over the substrate, the driver circuit portion including a second transistor;

wherein the first transistor includes;

a first gate electrode layer;

a gate insulating layer over the first gate electrode layer;

a first source electrode layer and a first drain electrode layer over the gate insulating layer;

a first oxide semiconductor layer over the gate insulating layer, the first source electrode layer, and the first drain electrode layer, the first oxide semiconductor layer being in contact with the gate insulating layer;

an oxide insulating layer over the first oxide semiconductor layer; and

a pixel electrode layer over the oxide insulating layer,

wherein the second transistor includes;

a second gate electrode layer;

the gate insulating layer over the second gate electrode layer;

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

a second source electrode layer and a second drain electrode layer over the second oxide semiconductor layer; and

the oxide insulating layer over the second oxide semiconductor layer, the second source electrode layer, and the second drain electrode layer, the oxide insulating layer being in contact with the second oxide semiconductor layer,

wherein each of the first gate electrode layer, the first oxide semiconductor layer, the first source electrode layer, and the first drain electrode layer has a light-transmitting property,

wherein a material of the second source electrode layer and the second drain electrode layer is different from a material of the first source electrode layer and the first drain electrode layer, and

wherein the material of the second source electrode layer and the second drain electrode layer is a metal having lower resistance than the material of the first source electrode layer and the first drain electrode layer.

2. The semiconductor device according to claim 1,

wherein a material of the second gate electrode layer is different from a material of the first gate electrode layer, and

wherein the material of the second gate electrode layer is a metal having lower resistance than the material of the first gate electrode layer.

3. The semiconductor device according to claim 1,

wherein the second oxide semiconductor layer includes a channel formation region and a region which overlaps with the second source electrode layer or the second drain electrode layer, and

wherein a thickness of the channel formation region is smaller than a thickness of the region.

4. The semiconductor device according to claim 3,

wherein the thickness of the channel formation region of the second transistor is the same as a thickness of the first oxide semiconductor layer of the first transistor.

5. The semiconductor device according to claim 1,

wherein the second transistor includes a conductive layer over the second oxide semiconductor layer with the oxide insulating layer therebetween.

6. The semiconductor device according to claim 1,

wherein the second source electrode layer and the second drain electrode layer comprise a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W.

7. The semiconductor device according to claim 1,

wherein the first source electrode layer, the first drain electrode layer, the first gate electrode layer, and the pixel electrode layer comprise a conductive metal oxide.

8. The semiconductor device according to claim 1, further comprising a capacitor in the pixel portion,

wherein the capacitor includes a capacitor wiring and a capacitor electrode overlapping with the capacitor wiring, and

wherein each of the capacitor wiring and the capacitor electrode has a light-transmitting property.

9. The semiconductor device according to claim 8,

wherein a material of the capacitor wiring is the same as a material of the first gate electrode layer, and

wherein a material of the capacitor electrode is the same as the material of the first source electrode layer and the first drain electrode layer.

10. A semiconductor device comprising:

a pixel portion formed over a substrate, the pixel portion including a first transistor, and

a driver circuit portion formed over the substrate, the driver circuit portion including a second transistor;

wherein the first transistor includes;

a first gate electrode layer;

a gate insulating layer over the first gate electrode layer;

a first source electrode layer and a first drain electrode layer over the gate insulating layer;

a first oxide semiconductor layer over the first source electrode layer and the first drain electrode layer, the first oxide semiconductor layer being in contact with the gate insulating layer;

an oxide insulating layer over the first oxide semiconductor layer; and

a pixel electrode layer over the oxide insulating layer,

wherein the second transistor includes;

a second gate electrode layer;

the gate insulating layer over the second gate electrode layer;

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

a second source electrode layer and a second drain electrode layer over the second oxide semiconductor layer; and

the oxide insulating layer over the second oxide semiconductor layer, the second source electrode layer, and the second drain electrode layer, the oxide insulating layer being in contact with the second oxide semiconductor layer,

wherein each of the first gate electrode layer, the first oxide semiconductor layer, the first source electrode layer, and the first drain electrode layer has a light-transmitting property,

wherein a material of the second source electrode layer and the second drain electrode layer is different from a material of the first source electrode layer and the first drain electrode layer,

wherein the material of the second source electrode layer and the second drain electrode layer is a metal having lower resistance than the material of the first source electrode layer and the first drain electrode layer, and

wherein the second gate electrode layer comprises a metal layer.

11. The semiconductor device according to claim 10, further comprising a second metal layer over and in contact with the second gate electrode layer.

12. The semiconductor device according to claim 10, further comprising a metal nitride film over and in contact with the second gate electrode layer.

13. The semiconductor device according to claim 10,

wherein a material of the second gate electrode layer is different from a material of the first gate electrode layer, and

wherein the material of the second gate electrode layer is a metal having lower resistance than the material of the first gate electrode layer.

14. The semiconductor device according to claim 10,

wherein the second oxide semiconductor layer includes a channel formation region and a region which overlaps with the second source electrode layer or the second drain electrode layer, and

wherein a thickness of the channel formation region is smaller than a thickness of the region.

15. The semiconductor device according to claim 14,

wherein the thickness of the channel formation region of the second transistor is the same as a thickness of the first oxide semiconductor layer of the first transistor.

16. The semiconductor device according to claim 10,

wherein the second transistor includes a conductive layer over the second oxide semiconductor layer with the oxide insulating layer therebetween.

17. The semiconductor device according to claim 10,

wherein the second source electrode layer and the second drain electrode layer comprise a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W.

18. The semiconductor device according to claim 10,

wherein the first source electrode layer, the first drain electrode layer, the first gate electrode layer, and the pixel electrode layer comprise a conductive metal oxide.

19. The semiconductor device according to claim 10, further comprising a capacitor in the pixel portion,

wherein the capacitor includes a capacitor wiring and a capacitor electrode overlapping with the capacitor wiring, and

wherein each of the capacitor wiring and the capacitor electrode has a light-transmitting property.

20. The semiconductor device according to claim 19,

wherein a material of the capacitor wiring is the same as a material of the first gate electrode layer, and

wherein a material of the capacitor electrode is the same as the material of the first source electrode layer and the first drain electrode layer.

21. A method for manufacturing a semiconductor device, the method comprising the steps of:

forming a first gate electrode layer and a second gate electrode layer in a pixel portion and a driver circuit portion, respectively, which are located over a substrate, using a first transparent metal oxide;

forming a gate insulating layer over the first gate electrode layer and the second gate electrode layer;

forming a first source electrode layer and a first drain electrode layer over the gate insulating layer in the pixel portion, using a second transparent metal oxide;

forming a first oxide semiconductor layer over the first gate electrode layer with the gate insulating layer, the first source electrode layer, and the first drain electrode layer interposed therebetween;

forming a second oxide semiconductor layer over the second gate electrode layer with the gate insulating layer interposed therebetween;

performing dehydration or dehydrogenation on the first oxide semiconductor layer and the second oxide semiconductor layer by heating in a gas selected from a nitrogen gas and an inert gas;

forming a second source electrode layer and a second drain electrode layer over the second oxide semiconductor layer, using a metal;

forming an oxide insulating layer over the first oxide semiconductor layer, the first source electrode layer, the first drain electrode layer, the second oxide semiconductor layer, the second source electrode layer, and the second drain electrode layer so that the oxide insulating layer is in contact with the first oxide semiconductor layer and the second oxide semiconductor layer ; and

forming a pixel electrode layer which is electrically connected to one of the first drain electrode layer and the first source electrode layer in the pixel portion, using a third transparent metal oxide.

22. The method according to claim 21, further comprising a step of forming a conductive layer over the oxide insulating layer in the driver circuit portion so that the conductive layer overlaps with the second gate electrode layer.

23. The method according to claim 21,

wherein the metal is selected from Al, Cr, Cu, Ta, Ti, Mo, and W.

24. The method according to claim 21, further comprising the steps of:

forming a capacitor wiring layer in the pixel portion using the first transparent metal oxide; and

forming a capacitor electrode over the capacitor wiring layer using the second transparent metal oxide so that the gate insulating layer is interposed between the capacitor wiring layer and the capacitor electrode.

25. A method for manufacturing a semiconductor device, comprising the steps of:

forming a first gate electrode layer in a pixel portion of a substrate, using a first transparent metal oxide;

forming a second gate electrode layer in a driver circuit portion over the substrate, using a first metal;

forming a gate insulating layer over the first gate electrode layer and the second gate electrode layer;

forming a first source electrode layer and a first drain electrode layer over the gate insulating layer in the pixel portion, using a second transparent metal oxide;

forming a first oxide semiconductor layer over the first gate electrode layer with the gate insulating layer, the first source electrode layer, and the first drain electrode layer interposed therebetween;

forming a second oxide semiconductor layer over the second gate electrode layer with the gate insulating layer interposed therebetween;

performing dehydration or dehydrogenation on the first oxide semiconductor layer and the second oxide semiconductor layer by heating in a gas selected from a nitrogen gas and an inert gas;

forming a second source electrode layer and a second drain electrode layer over the second oxide semiconductor layer, using a second metal;

forming an oxide insulating layer over the first oxide semiconductor layer, the first source electrode layer, the first drain electrode layer, the second oxide semiconductor layer, the second source electrode layer, and the second drain electrode layer so that the oxide insulating layer is in contact with the first oxide semiconductor layer and the second oxide semiconductor layer; and

forming a pixel electrode layer which is electrically connected to one of the first drain electrode layer and the first source electrode layer in the pixel portion, using a third transparent metal oxide.

26. The method according to claim 25, further comprising a step of forming a conductive layer over the oxide insulating layer in the driver circuit portion so that the conductive layer overlaps with the second gate electrode layer.

27. The method according to claim 25,

wherein the first metal is selected from Ta, W, Ti, Mo, Al, and Cu.

28. The method according to claim 25, further comprising the steps of:

forming a capacitor wiring layer in the pixel portion, using the first transparent metal oxide; and

forming a capacitor electrode over the capacitor wiring layer, using the second transparent metal oxide so that the gate insulating layer is interposed between the capacitor wiring layer and the capacitor electrode.

29. The method according to claim 25, further comprising a step of forming a metal layer over and in contact with the second gate electrode layer.

30. The method according to claim 25, further comprising a step of forming a metal nitride film over and in contact with the second gate electrode layer.