DISPLAY DEVICE

• US 20150153599A1
• Filed: 11/25/2014
• Published: 06/04/2015
• Est. Priority Date: 12/02/2013
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: YAMAZAKI, Shunpei, OKAZAKI, Kenichi, KATAYAMA, Masahiro
• Granted Patent: US 9,825,057 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 27/1251 comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• 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
• CPC Class Codes: H10K 59/1201 Manufacture or treatment
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs

Abstract

To provide a display device in which plural kinds of circuits are formed over one substrate and plural kinds of transistors corresponding to characteristics of the plural kinds of circuits are provided. The display device includes a pixel portion and a driver circuit that drives the pixel portion over one substrate. The pixel portion includes a first transistor including a first oxide semiconductor film. The driver circuit includes a second transistor including a second oxide semiconductor film. The first oxide semiconductor film and the second oxide semiconductor film are formed over one insulating surface. A channel length of the first transistor is longer than a channel length of the second transistor. The channel length of the first transistor is greater than or equal to 2.5 micrometer.

Claims

1. A display device comprising:

a pixel portion over a substrate; and

a driver circuit that drives the pixel portion over the substrate,

wherein the pixel portion comprises a first transistor comprising a first oxide semiconductor film,

wherein the driver circuit comprises a second transistor comprising a second oxide semiconductor film and a third oxide semiconductor film,

wherein the first oxide semiconductor film and the second oxide semiconductor film which have different compositions are on an insulating surface,

wherein a channel length of the first transistor is longer than a channel length of the second transistor, and

wherein the third oxide semiconductor film is in contact with a side surface of the second oxide semiconductor film.

2. The display device according to claim 1,

wherein the first oxide semiconductor film and the third oxide semiconductor film are formed in a same step.

3. The display device according to claim 1,

wherein the first oxide semiconductor film and the third oxide semiconductor film comprise a same material.

4. The display device according to claim 1,

wherein the channel length of the first transistor is greater than or equal to 2.5 μ

m and the channel length of the second transistor is less than 2.5 μ

m.

5. The display device according to claim 1,

wherein the channel length of the first transistor is greater than or equal to 1 μ

m and less than or equal to 2.1 μ

m.

6. The display device according to claim 1,

wherein the second transistor comprises a gate electrode layer, the second oxide semiconductor film over the gate electrode layer, an insulating layer over the second oxide semiconductor film, and a conductive layer over the insulating layer,

wherein the insulating layer covers the second oxide semiconductor film and is in contact with a gate insulating layer, and

wherein in a channel width direction of the second oxide semiconductor film of the second transistor, the conductive layer overlaps with a channel formation region of the second oxide semiconductor film and is electrically connected to the gate electrode layer.

7. An electronic device comprising the display device according to claim 1.

8. A display device comprising:

a pixel portion over a substrate; and

a driver circuit that drives the pixel portion over the substrate,

wherein the pixel portion comprises a first transistor comprising a first oxide semiconductor film,

wherein the driver circuit comprises a second transistor comprising a second oxide semiconductor film,

wherein the first oxide semiconductor film and the second oxide semiconductor film are on an insulating surface,

wherein a channel length of the first transistor is longer than a channel length of the second transistor, and

wherein the channel length of the first transistor is greater than or equal to 2.5 μ

m.

9. The display device according to claim 8, further comprising a third oxide semiconductor film,

wherein the first oxide semiconductor film and the third oxide semiconductor film comprise a same material.

10. The display device according to claim 8,

wherein the channel length of the second transistor is less than 2.5 μ

m.

11. The display device according to claim 8,

wherein the channel length of the first transistor is greater than or equal to 1 μ

m and less than or equal to 2.1 μ

m.

12. The display device according to claim 8,

wherein the second transistor comprises a gate electrode layer, the second oxide semiconductor film over the gate electrode layer, an insulating layer over the second oxide semiconductor film, and a conductive layer over the insulating layer,

wherein the insulating layer covers the second oxide semiconductor film and is in contact with a gate insulating layer, and

wherein in a channel width direction of the second oxide semiconductor film of the second transistor, the conductive layer overlaps with a channel formation region of the second oxide semiconductor film and is electrically connected to the gate electrode layer.

13. An electronic device comprising the display device according to claim 8.

14. A display device comprising:

a pixel portion over a substrate; and

a driver circuit that drives the pixel portion over the substrate,

wherein the pixel portion comprises a first transistor comprising a first oxide semiconductor film,

wherein the driver circuit comprises a second transistor comprising a second oxide semiconductor film, a third oxide semiconductor film over the second oxide semiconductor film, and a fourth oxide semiconductor film over the third oxide semiconductor film,

wherein the first oxide semiconductor film and the second oxide semiconductor film are on an insulating surface,

wherein a channel length of the first transistor is longer than a channel length of the second transistor,

wherein a top surface and a side surface of the third oxide semiconductor film are covered with the fourth oxide semiconductor film, and

wherein a bottom surface of the third oxide semiconductor film is in contact with a top surface of the second oxide semiconductor film.

15. The display device according to claim 14, wherein the first oxide semiconductor film and the fourth oxide semiconductor film are formed in a same step.

16. The display device according to claim 14, wherein the first oxide semiconductor film and the fourth oxide semiconductor film comprise a same material.

17. An electronic device comprising the display device according to claim 14.