Liquid crystal display device and method for manufacturing the same

• US 8,218,099 B2
• Filed: 08/30/2010
• Issued: 07/10/2012
• Est. Priority Date: 09/04/2009
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Sakakura, Masayuki, Sakata, Junichiro, Tsubuku, Masashi, Akimoto, Kengo, Hosoba, Miyuki, Oikawa, Yoshiaki
• Primary Examiner(s): Doan, Jennifer
• Application Number:
  US12/871,162
• Publication Number:
  US 20110058116A1
• Time in Patent Office: 680 Days
• Field of Search: 349/19, 349/33, 349/41, 349/42, 349/43, 349/44, 349/45
• US Class Current: 349/43
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO

Abstract

An object is to provide an active matrix liquid crystal display device in which plural kinds of circuits are formed over one substrate and plural kinds of thin film transistors are provided corresponding to characteristics of the plural kinds of circuits. An inverted-coplanar thin film transistor including an oxide semiconductor layer which is over and overlaps with a source electrode layer and a drain electrode layer is used for a pixel thin film transistor. A channel-protective thin film transistor is used for a driver-circuit thin film transistor is used. In addition, main parts of the pixel thin film transistor are formed using a light-transmitting material, so that the aperture ratio is increased.

Claims

1. An active matrix liquid crystal display 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 comprises;

a first gate electrode layer over the substrate;

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 which is over the gate insulating layer and overlaps with the first source electrode layer and the first drain electrode layer;

an oxide insulating layer which is in contact with the first oxide semiconductor layer;

a connection electrode layer which is connected to at least one of the first source electrode layer and the first drain electrode layer; and

a pixel electrode layer which is over the oxide insulating layer and electrically connected to the first drain electrode layer,

wherein the second transistor comprises;

a second gate electrode layer over the substrate;

the gate insulating layer over the substrate;

a second oxide semiconductor layer over the gate insulating layer;

the oxide insulating layer over the second oxide semiconductor layer; and

a second source electrode layer and a second drain electrode layer over the oxide insulating layer,

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

wherein a channel formation region of the second oxide semiconductor layer and a peripheral portion of the second oxide semiconductor layer are in contact with the oxide insulating layer.

2. The active matrix liquid crystal display device according to claim 1,

wherein a material of the second gate electrode layer, and a material of the second source electrode layer and the second drain electrode layer are different from a material of the first gate electrode layer, a material of the first source electrode layer, and the first drain electrode layer, respectively, and

wherein the material of the second gate electrode layer, and the material of the second source electrode layer, and the second drain electrode layer are a conductive material with lower resistance than the material of the first source electrode layer and the first drain electrode layer.

3. The active matrix liquid crystal display device according to claim 1, wherein the connection electrode layer is formed from a film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, as a main component, or a stacked film including an alloy film of any of the elements in combination.

4. The active matrix liquid crystal display device according to claim 1, wherein the second source electrode layer and the second drain electrode layer are formed using the same material as a material of the connection electrode layer.

5. The active matrix liquid crystal display device according to claim 1, wherein the first source electrode layer and the first drain electrode layer are formed using indium oxide, indium tin oxide, indium zinc oxide, or zinc oxide.

6. The active matrix liquid crystal display device according to claim 1, wherein the oxide insulating layer is formed from a silicon oxide film or an aluminum oxide film.

7. The active matrix liquid crystal display device according to claim 1, further comprising:

an oxide conductive layer provided between the second oxide semiconductor layer and the second source electrode layer and between the second oxide semiconductor layer and the second drain electrode layer.

8. The active matrix liquid crystal display device according to claim 7, wherein the oxide conductive layer comprises the same material as the first source electrode layer and the first drain electrode layer.

9. An active matrix liquid crystal display 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 comprises;

a first gate electrode layer over the substrate;

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 which is over the gate insulating layer and overlaps with the first source electrode layer and the first drain electrode layer;

an oxide insulating layer which is in contact with the first oxide semiconductor layer;

a connection electrode layer which is connected to at least one of the first source electrode layer and the first drain electrode layer;

an insulating layer over the oxide insulating layer and the connection electrode layer; and

a pixel electrode layer which is over the insulating layer and electrically connected to the first drain electrode layer,

wherein the second transistor comprises;

a second gate electrode layer over the substrate;

the gate insulating layer over the substrate;

a second oxide semiconductor layer over the gate insulating layer;

the oxide insulating layer over the second oxide semiconductor layer;

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

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

a conductive layer over the insulating layer which overlaps the second oxide semiconductor layer and the oxide insulating layer,

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

wherein a channel formation region of the second oxide semiconductor layer and a peripheral portion of the second oxide semiconductor layer are in contact with the oxide insulating layer.

10. The active matrix liquid crystal display device according to claim 9,

wherein a material of the second gate electrode layer, and a material of the second source electrode layer, and the second drain electrode layer are different from a material of the first gate electrode layer, a material of the first source electrode layer, and the first drain electrode layer, respectively and

wherein the material of the second gate electrode layer, and the material of the second source electrode layer, and the second drain electrode layer are a conductive material with lower resistance than the material of the first source electrode layer and the first drain electrode layer.

11. The active matrix liquid crystal display device according to claim 9, wherein the connection electrode layer is formed from a film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, as a main component, or a stacked film including an alloy film of any of the elements in combination.

12. The active matrix liquid crystal display device according to claim 9, wherein the second source electrode layer and the second drain electrode layer are formed using the same material as a material of the connection electrode layer.

13. The active matrix liquid crystal display device according to claim 9, wherein the first source electrode layer and the first drain electrode layer are formed using indium oxide, indium tin oxide, indium zinc oxide, or zinc oxide.

14. The active matrix liquid crystal display device according to claim 9, wherein the oxide insulating layer is formed from a silicon oxide film or an aluminum oxide film.

15. The active matrix liquid crystal display device according to claim 9, further comprising:

an oxide conductive layer provided between the second oxide semiconductor layer and the second source electrode layer, and between the second oxide semiconductor layer and the second drain electrode layer.

16. The active matrix liquid crystal display device according to claim 15, wherein the oxide conductive layer comprises the same material as the first source electrode layer and the first drain electrode layer.

17. An active matrix liquid crystal display device comprising:

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

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

wherein the first transistor comprises;

a first gate electrode layer over the first substrate;

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 which is over the gate insulating layer and overlaps with the first source electrode layer and the first drain electrode layer;

an oxide insulating layer which is in contact with the first oxide semiconductor layer;

a connection electrode layer which is connected to at least one of the first source electrode layer and the first drain electrode layer; and

a pixel electrode layer which is over the oxide insulating layer and electrically connected to the first drain electrode layer,

wherein the second transistor comprises;

a second gate electrode layer over the first substrate;

the gate insulating layer over the first substrate;

a second oxide semiconductor layer over the gate insulating layer;

the oxide insulating layer over the second oxide semiconductor layer; and

a second source electrode layer and a second drain electrode layer over the oxide insulating layer,

a second electrode over the first transistor and the second transistor;

a second substrate over the second electrode; and

a liquid crystal layer interposed between the first substrate and the second substrate,

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

wherein a channel formation region of the second oxide semiconductor layer and a peripheral portion of the second oxide semiconductor layer are in contact with the oxide insulating layer.

18. The active matrix liquid crystal display device according to claim 17,

wherein a material of the second gate electrode layer, and a material of the second source electrode layer, and the second drain electrode layer are different from a material of the first gate electrode layer, a material of the first source electrode layer, and the first drain electrode layer, respectively and

wherein the material of the second gate electrode layer, and the material of the second source electrode layer, and the second drain electrode layer are a conductive material with lower resistance than the material of the first source electrode layer and the first drain electrode layer.

19. The active matrix liquid crystal display device according to claim 17, wherein the connection electrode layer is formed from a film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, as a main component, or a stacked film including an alloy film of any of the elements in combination.

20. The active matrix liquid crystal display device according to claim 17, wherein the second source electrode layer and the second drain electrode layer are formed using the same material as a material of the connection electrode layer.

21. The active matrix liquid crystal display device according to claim 17, wherein the first source electrode layer and the first drain electrode layer are formed using indium oxide, indium tin oxide, indium zinc oxide, or zinc oxide.

22. The active matrix liquid crystal display device according to claim 17, wherein the oxide insulating layer is formed from a silicon oxide film or an aluminum oxide film.

23. The active matrix liquid crystal display device according to claim 17, further comprising:

an oxide conductive layer provided between the second oxide semiconductor layer and the second source electrode layer, and between the second oxide semiconductor layer and the second drain electrode layer.

24. The active matrix liquid crystal display device according to claim 23, wherein the oxide conductive layer comprises the same material as the first source electrode layer and the first drain electrode layer.

25. The active matrix liquid crystal display device according to claim 17, wherein the liquid crystal layer is a material exhibiting a blue phase.

26. A method for manufacturing an active matrix liquid crystal display device comprising the steps of:

forming a first gate electrode layer and a second gate electrode layer over a substrate having an insulating surface;

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 to overlap with the first gate electrode layer;

forming an oxide semiconductor film over the first source electrode layer, the first drain electrode layer and the gate insulating layer;

forming a first oxide semiconductor layer and a second oxide semiconductor layer over the gate insulating layer by selectively removing the oxide semiconductor film;

heating the first oxide semiconductor layer and the second oxide semiconductor layer in order to decrease a hydrogen concentration in the first oxide semiconductor layer and the second oxide semiconductor layer;

forming an oxide insulating layer which is over the first oxide semiconductor layer and in contact with a part of the second oxide semiconductor layer and an upper surface and a side surface of the second oxide semiconductor layer;

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

forming a pixel electrode layer which is over the oxide insulating layer and electrically connected to the first drain electrode layer,

wherein the first oxide semiconductor layer overlaps with the first gate electrode layer, a part of the first source electrode layer, and a part of the first drain electrode layer, and the second oxide semiconductor layer overlaps with the second gate electrode layer, and

wherein a channel formation region of the second oxide semiconductor layer and a peripheral portion of the second oxide semiconductor layer are in contact with the oxide insulating layer.

27. A method for manufacturing an active matrix liquid crystal display device comprising the steps of:

forming a first gate electrode layer and a second gate electrode layer over a substrate having an insulating surface;

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 to overlap with the first gate electrode layer;

forming an oxide semiconductor film over the first source electrode layer, the first drain electrode layer and the gate insulating layer;

heating the oxide semiconductor film in order to decrease a hydrogen concentration in the oxide semiconductor film;

forming a first oxide semiconductor layer and a second oxide semiconductor layer over the gate insulating layer by selectively removing the oxide semiconductor film;

forming an oxide insulating layer which is over the first oxide semiconductor layer and in contact with a part of the second oxide semiconductor layer and an upper surface and a side surface of the second oxide semiconductor layer;

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

forming a pixel electrode layer which is over the oxide insulating layer and electrically connected to the first drain electrode layer,

wherein the first oxide semiconductor layer overlaps with the first gate electrode layer, a part of the first source electrode layer, and a part of the first drain electrode layer, and the second oxide semiconductor layer overlaps with the second gate electrode layer, and

wherein a channel formation region of the second oxide semiconductor layer and a peripheral portion of the second oxide semiconductor layer are in contact with the oxide insulating layer.