Display device

• US 9,825,057 B2
• Filed: 11/25/2014
• Issued: 11/21/2017
• 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
• Primary Examiner(s): HALL, VICTORIA KATHLEEN
• Application Number:
  US14/553,269
• Publication Number:
  US 20150153599A1
• Time in Patent Office: 1,092 Days
• Field of Search: None
• 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 configured to drive 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 second transistor has a larger number of oxide semiconductor films than the first transistor,

wherein the first oxide semiconductor film and the second oxide semiconductor film have different compositions,

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

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

wherein the second oxide semiconductor film comprises indium and zinc, and

wherein a proportion of indium atoms is higher than a proportion of zinc atoms in 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 less than or equal to 20 μ

m, and

wherein the channel length of the second transistor is greater than or equal to 1.45 μ

m and less than or equal to 2.2 μ

m.

5. The display device according to claim 1, wherein the channel length of the second 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. The display device according to claim 1, wherein the first oxide semiconductor film and the second oxide semiconductor film are on an insulating surface.

9. The display device according to claim 1, wherein the first oxide semiconductor film and the third oxide semiconductor film have same compositions.

10. The display device according to claim 1,

wherein the first oxide semiconductor film and the third oxide semiconductor film each comprises indium and zinc, and

wherein a proportion of indium atoms is lower than or equal to a proportion of zinc atoms in each of the first oxide semiconductor film and the third oxide semiconductor film.

11. A display device comprising:

a pixel portion over a substrate; and

a driver circuit configured to drive 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 have different compositions,

wherein the second transistor has a larger number of oxide semiconductor films than the first transistor,

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

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

m and less than or equal to 20 μ

m,

wherein the second oxide semiconductor film comprises indium and zinc, and

wherein a proportion of indium atoms is higher than a proportion of zinc atoms in the second oxide semiconductor film.

12. The display device according to claim 11,

wherein the second transistor further comprises a third oxide semiconductor film over the second oxide semiconductor film, and

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

13. The display device according to claim 11, wherein the channel length of the second transistor is greater than or equal to 1.45 μ

m and less than or equal to 2.2 μ

m.

14. The display device according to claim 11, wherein the channel length of the second transistor is greater than or equal to 1 μ

m and less than or equal to 2.1 μ

m.

15. The display device according to claim 11,

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.

16. An electronic device comprising the display device according to claim 11.

17. The display device according to claim 11, wherein the first oxide semiconductor film and the second oxide semiconductor film are on an insulating surface.

18. A display device comprising:

a pixel portion over a substrate; and

a driver circuit configured to drive 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 second transistor has a larger number of oxide semiconductor films than the first transistor,

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

wherein the fourth oxide semiconductor film covers side surfaces of the second oxide semiconductor film and the third oxide semiconductor film,

wherein the third oxide semiconductor film comprises indium and zinc, and

wherein a proportion of indium atoms is higher than a proportion of zinc atoms in the third oxide semiconductor film.

19. The display device according to claim 18, wherein the first oxide semiconductor film and the fourth oxide semiconductor film are formed in a same step.

20. The display device according to claim 18, wherein the first oxide semiconductor film and the fourth oxide semiconductor film comprise a same material.

21. An electronic device comprising the display device according to claim 18.

22. The display device according to claim 18, wherein the first oxide semiconductor film and the second oxide semiconductor film are on an insulating surface.

23. The display device according to claim 18, wherein the first oxide semiconductor film and the second oxide semiconductor film have different compositions.

24. A semiconductor device comprising:

a pixel circuit comprising a first transistor over a substrate; and

a driver circuit comprising a second transistor over the substrate, the driver circuit configured to drive the pixel circuit,

wherein the first transistor comprises a first oxide semiconductor film,

wherein the second transistor comprises;

a gate electrode;

a second oxide semiconductor film over the gate electrode;

a third oxide semiconductor film over the second oxide semiconductor film;

a fourth oxide semiconductor film over the third oxide semiconductor film;

a pair of electrodes over the fourth oxide semiconductor film; and

a conductive film over the fourth oxide semiconductor film, the conductive film being electrically connected to the gate electrode,

wherein the second transistor has a larger number of oxide semiconductor films than the first transistor,

wherein the fourth oxide semiconductor film covers side surfaces of the second oxide semiconductor film and the third oxide semiconductor film,

wherein the third oxide semiconductor film comprises indium and zinc, and

wherein a proportion of indium atoms is higher than a proportion of zinc atoms in the third oxide semiconductor film.

25. The semiconductor device according to claim 24, wherein the first oxide semiconductor film and the fourth oxide semiconductor film comprise a same material.

26. The semiconductor device according to claim 24,

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

m and less than or equal to 20 μ

m, and

wherein a channel length of the second transistor is greater than or equal to 1.45 μ

m and less than or equal to 2.2 μ

m.

27. The semiconductor device according to claim 24, wherein a channel length of the first transistor is longer than a channel length of the second transistor.

28. An electronic device comprising the semiconductor device according to claim 24.

29. The semiconductor device according to claim 24, wherein the first oxide semiconductor film and the second oxide semiconductor film are on an insulating surface.

30. The semiconductor device according to claim 24, wherein the first oxide semiconductor film and the second oxide semiconductor film have different compositions.