Display device and electronic appliance

• US 9,018,624 B2
• Filed: 09/05/2013
• Issued: 04/28/2015
• Est. Priority Date: 09/13/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): HO, TU TU V
• Application Number:
  US14/018,770
• Publication Number:
  US 20140070208A1
• Time in Patent Office: 600 Days
• Field of Search: 257/43, 257/59, 257/72
• US Class Current: 257/43
• 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 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• 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: H10K 59/1201 Manufacture or treatment
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors

Abstract

A display device with low manufacturing cost, a display device with low power consumption, a display device capable of being formed over a large substrate, a display device with a high aperture ratio of a pixel, and a display device with high reliability are provided. The display device includes a transistor electrically connected to a light-transmitting pixel electrode and a capacitor. The transistor includes a gate electrode, a gate insulating film, and a first multilayer film including an oxide semiconductor layer. The capacitor includes the pixel electrode and a second multilayer film overlapping with the pixel electrode, positioned at a predetermined distance from the pixel electrode, and having the same layer structure as the first multilayer film. A channel formation region of the transistor is at least one layer, which is not in contact with the gate insulating film, of the first multilayer film.

Claims

1. A display device comprising:

a transistor comprising;

a gate electrode;

a first multilayer film comprising an oxide semiconductor layer comprising a channel formation region of the transistor; and

a gate insulating film between the gate electrode and the first multilayer film;

a pixel electrode electrically connected to the transistor; and

a capacitor comprising a second multilayer film,

wherein the pixel electrode overlaps with the second multilayer film,

wherein the first multilayer film comprises the same layer structure as the second multilayer film,

wherein the oxide semiconductor layer is provided apart from the gate insulating film, and

wherein the second multilayer film is provided apart from the pixel electrode.

2. The display device according to claim 1, further comprising a first oxide layer between the gate insulating film and the oxide semiconductor layer.

3. The display device according to claim 2, further comprising a second oxide layer in contact with the oxide semiconductor layer.

4. The display device according to claim 2,

wherein electron affinity of the oxide semiconductor layer is higher than electron affinity of the first oxide layer by 0.2 eV or more.

5. The display device according to claim 2,

wherein concentration of aluminum, silicon, titanium, gallium, germanium, yttrium, zirconium, tin, lanthanum, cerium, or hafnium in the first oxide layer is 1.5 times or more as high as that in the oxide semiconductor layer.

6. The display device according to claim 2,

wherein the first oxide layer and the oxide semiconductor layer are each an In—

Ga—

Zn-based oxide,

wherein the first oxide layer has an atomic ratio of In;

Ga;

Zn=x₁;

y₁;

z₁,

wherein the oxide semiconductor layer has an atomic ratio of In;

Ga;

Zn=x₂;

y₂;

z₂, and

wherein y₁/x₁ is 1.5 times or more as large as y₂/x₂.

7. The display device according to claim 2,

wherein the oxide semiconductor layer has a crystalline structure, and

wherein the first oxide layer has a lower crystallinity than the oxide semiconductor layer.

8. The display device according to claim 1, further comprising a capacitor line electrically connected to the second multilayer film.

9. An electronic appliance comprising the display device according to claim 1.

10. A display device comprising:

a transistor comprising;

a gate electrode;

a first multilayer film comprising;

a first oxide layer; and

an oxide semiconductor layer comprising a channel formation region of the transistor; and

a gate insulating film between the gate electrode and the first multilayer film;

a pixel electrode electrically connected to the transistor; and

a capacitor comprising a second multilayer film,

wherein the pixel electrode overlaps with the second multilayer film,

wherein the first multilayer film comprises the same layer structure as the second multilayer film,

wherein the first oxide layer is provided between the gate insulating film and the oxide semiconductor layer, and

wherein the second multilayer film is provided apart from the pixel electrode.

11. The display device according to claim 10, further comprising a second oxide layer in contact with the oxide semiconductor layer.

12. The display device according to claim 10,

wherein electron affinity of the oxide semiconductor layer is higher than electron affinity of the first oxide layer by 0.2 eV or more.

13. The display device according to claim 10,

wherein concentration of aluminum, silicon, titanium, gallium, germanium, yttrium, zirconium, tin, lanthanum, cerium, or hafnium in the first, oxide layer is 1.5 times or more as high as that in the oxide semiconductor layer.

14. The display device according to claim 10,

wherein the first oxide layer and the oxide semiconductor layer are each an In—

Ga—

Zn-based oxide,

wherein the first oxide layer has an atomic ratio of In;

Ga;

Zn=x₁;

y₁;

z₁,

wherein the oxide semiconductor layer has an atomic ratio of In;

Ga;

Zn=x₂;

y₂;

z₂, and

wherein y₁/x₁ is 1.5 times or more as large as y₂/x₂.

15. The display device according to claim 10,

wherein the oxide semiconductor layer has a crystalline structure, and

wherein the first oxide layer has a lower crystallinity than the oxide semiconductor layer.

16. The display device according to claim 10, further comprising a capacitor line electrically connected to the second multilayer film.

17. An electronic appliance comprising the display device according to claim 10.