Light emitting device

• US 8,546,825 B2
• Filed: 07/23/2012
• Issued: 10/01/2013
• Est. Priority Date: 01/17/2001
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Koyama, Jun, Arao, Tatsuya, Azami, Munehiro
• Primary Examiner(s): Malsawma, Lex
• Application Number:
  US13/555,292
• Publication Number:
  US 20120286320A1
• Time in Patent Office: 435 Days
• Field of Search: 257/89, 257/E27.12, 257/E51.018, 257/E33.005
• US Class Current: 257/89
• 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 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/78633 with a light shield
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/122 Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/124 Insulating layers formed between TFT elements and OLED elements
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals

Abstract

A light emitting device is provided which can prevent a change in gate voltage due to leakage or other causes and at the same time can prevent the aperture ratio from lowering. A capacitor storage is formed from a connection wiring line, an insulating film, and a capacitance wiring line. The connection wiring line is formed over a gate electrode and an active layer of a TFT of a pixel, and is connected to the active layer. The insulating film is formed on the connection wiring line. The capacitance wiring line is formed on the insulating film. This structure enables the capacitor storage to overlap the TFT, thereby increasing the capacity of the capacitor storage while keeping the aperture ratio from lowering. Accordingly, a change in gate voltage due to leakage or other causes can be avoided to prevent a change in luminance of an OLED and flickering of screen in analog driving.

Claims

1. A light-emitting device comprising:

a pixel portion, the pixel portion including;

a transistor, the transistor including a semiconductor region, a gate insulating film over the semiconductor region, and a gate electrode over the gate insulating film;

a first insulating film over the gate electrode;

a first conductive layer over the first insulating film, wherein the first conductive layer is electrically connected to the semiconductor region;

a second insulating film over the first conductive layer;

a second conductive layer over the second insulating film, wherein the second conductive layer is electrically connected to the first conductive layer through a first opening provided in the second insulating film;

a third insulating film covering an end portion of the second conductive layer; and

a light emitting layer over the third insulating film and the second conductive layer,

wherein a second opening adjacent to the first opening is provided in the second insulating film, and

wherein the second opening is wider than the first opening.

2. The light-emitting device according to claim 1, wherein the second conductive layer is a pixel electrode.

3. The light-emitting device according to claim 1, further comprising a capacitor wiring covering the second opening.

4. The light-emitting device according to claim 1, wherein the light-emitting device is incorporated in one selected from the group consisting of a display device, a camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

5. The light-emitting device according to claim 1, wherein the transistor is formed over a glass substrate.

6. A light-emitting device comprising:

a pixel portion, the pixel portion including;

a transistor, the transistor including a semiconductor region, a gate insulating film over the semiconductor region, and a gate electrode over the gate insulating film;

a first insulating film over the gate electrode;

a first conductive layer over the first insulating film, wherein the first conductive layer is electrically connected to the semiconductor region;

a second insulating film over the first conductive layer;

a second conductive layer over the second insulating film, wherein the second conductive layer is electrically connected to the first conductive layer through a first opening provided in the second insulating film;

a third insulating film covering an end portion of the second conductive layer; and

a light emitting layer over the third insulating film and the second conductive layer,

wherein a second opening adjacent to the first opening is provided in the second insulating film,

wherein the second opening is wider than the first opening, and

wherein a side surface of the second opening has a tapered shape.

7. The light-emitting device according to claim 6, wherein the second conductive layer is a pixel electrode.

8. The light-emitting device according to claim 6, further comprising a capacitor wiring covering the second opening.

9. The light-emitting device according to claim 6, wherein the light-emitting device is incorporated in one selected from the group consisting of a display device, a camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

10. The light-emitting device according to claim 6, wherein the transistor is formed over a glass substrate.

11. A light-emitting device comprising:

a pixel portion, the pixel portion including;

a transistor, the transistor including a semiconductor region, a gate insulating film over the semiconductor region, and a gate electrode over the gate insulating film;

a first insulating film over the gate electrode;

a first conductive layer over the first insulating film, wherein the first conductive layer is electrically connected to the semiconductor region;

a second insulating film over the first conductive layer;

a second conductive layer over the second insulating film, wherein the second conductive layer is electrically connected to the first conductive layer through a first opening provided in the second insulating film;

a third insulating film covering an end portion of the second conductive layer; and

a light emitting layer over the third insulating film and the second conductive layer,

wherein a second opening adjacent to the first opening is provided in the second insulating film,

wherein the second opening is wider than the first opening, and

wherein a fourth insulating film is provided under the second opening, and a third conductive layer is provided under the fourth insulating film.

12. The light-emitting device according to claim 11, wherein the second conductive layer is a pixel electrode.

13. The light-emitting device according to claim 11, further comprising a capacitor wiring covering the second opening.

14. The light-emitting device according to claim 13, wherein a capacitor storage is formed by the third conductive layer, the fourth insulating film and the capacitor wiring.

15. The light-emitting device according to claim 11, wherein the light-emitting device is incorporated in one selected from the group consisting of a display device, a camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

16. The light-emitting device according to claim 11, wherein the transistor is formed over a glass substrate.