Light emitting device

• US 8,324,618 B2
• Filed: 03/28/2012
• Issued: 12/04/2012
• Est. Priority Date: 11/09/2001
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Udagawa, Makoto, Hayakawa, Masahiko, Koyama, Jun, Osame, Mitsuaki, Anzai, Aya
• Primary Examiner(s): HA, NATHAN W
• Application Number:
  US13/432,009
• Publication Number:
  US 20120181540A1
• Time in Patent Office: 251 Days
• Field of Search: 257/59, 257/40, 257/72, 257/E29.273, 438/460, 438/462, 438/22
• US Class Current: 257/40
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• 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 29/78675 with normal-type structure, e.g. with top gate
• 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 50/80 Constructional details
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals

Abstract

The present invention provides a TFT that has a channel length particularly longer than that of an existing one, specifically, several tens to several hundreds times longer than that of the existing one, and thereby allowing turning to an on-state at a gate voltage particularly higher than the existing one and driving, and allowing having a low channel conductance gd. According to the present invention, not only the simple dispersion of on-current but also the normalized dispersion thereof can be reduced, and other than the reduction of the dispersion between the individual TFTs, the dispersion of the OLEDs themselves and the dispersion due to the deterioration of the OLED can be reduced.

Claims

1. A light emitting device comprising:

a first wiring;

a second wiring;

a first transistor over a substrate;

a second transistor over the substrate;

an insulating film over the second transistor;

a first electrode over the insulating film;

an organic compound layer over the first electrode;

a second electrode over the organic compound layer;

a silicon nitride film over the second electrode; and

wherein the first transistor comprises a first channel region and a second channel region, a first gate and a second gate corresponding to the first channel region and the second channel region respectively,

wherein the first wiring is directly connected to the first gate and the second gate of the first transistor,

wherein the second wiring is directly connected to one of a source and a drain of the second transistor,

wherein one of a source and a drain of the first transistor is directly connected to a gate of the second transistor,

wherein a channel width of the second transistor is smaller than a channel length of the second transistor, and

wherein the first wiring is parallel to the second wiring.

2. A light emitting device according to claim 1, wherein the second transistor comprises a polysilicon film.

3. A light emitting device as set forth in claim 1, wherein a ratio of the channel width of the second transistor to the channel length of the second transistor is from 0.1 to 0.01.

4. A light emitting device according to claim 1, wherein the second transistor is an n-channel type transistor.

5. A light emitting device according to claim 1, wherein the light emitting device is incorporated into an electronic equipment selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a recording medium, a digital camera, a mobile phone and a display.

6. A light emitting device comprising:

a first wiring;

a second wiring;

a first transistor over a substrate;

a second transistor over the substrate;

an insulating film over the second transistor;

a first electrode over the insulating film;

an organic compound layer over the first electrode;

a second electrode over the organic compound layer;

a silicon nitride film over the second electrode; and

an organic resin over the second electrode;

wherein the first transistor comprises a first channel region, a second channel region, a first gate, and a second gate,

wherein the first wiring is directly connected to the first gate and the second gate of the first transistor,

wherein the second wiring is directly connected to one of a source and a drain of the second transistor,

wherein one of a source and a drain of the first transistor is directly connected to a gate of the second transistor,

wherein a channel width of the second transistor is smaller than a channel length of the second transistor, and

wherein the first wiring does not cross the second wiring.

7. A light emitting device according to claim 6, wherein the second transistor comprises a polysilicon film.

8. A light emitting device as set forth in claim 6, wherein a ratio of the channel width W of the second transistor to the channel length of the second transistor is from 0.1 to 0.01.

9. A light emitting device according to claim 6, wherein the second transistor is an n-channel type transistor.

10. A light emitting device according to claim 6, wherein the light emitting device is incorporated into an electronic equipment selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a recording medium, a digital camera, a mobile phone and a display.

11. A light emitting device comprising:

a first wiring;

a second wiring;

a first transistor over a substrate;

a second transistor over the substrate;

an insulating film over the second transistor;

a first electrode over the insulating film;

an organic compound layer over the first electrode;

a second electrode over the organic compound layer;

a silicon nitride film over the second electrode; and

an organic resin over the second electrode;

wherein the first transistor comprises a first channel region, a second channel region, a first gate, and a second gate,

wherein the first wiring is directly connected to the first gate and the second gate of the first transistor,

wherein the second wiring is directly connected to one of a source and a drain of the second transistor,

wherein one of a source and a drain of the first transistor is directly connected to a gate of the second transistor,

wherein a channel width of the second transistor is smaller than a channel length of the second transistor, and

wherein an extended direction of the first wiring is parallel to an extended direction of the second wiring.

12. A light emitting device according to claim 11, wherein the second transistor comprises a polysilicon film.

13. A light emitting device as set forth in claim 11, wherein a ratio of the channel width of the second transistor to the channel length of the second transistor is from 0.1 to 0.01.

14. A light emitting device according to claim 11, wherein the second transistor is an n-channel type transistor.

15. A light emitting device according to claim 11, wherein the light emitting device is incorporated into an electronic equipment selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a recording medium, a digital camera, a mobile phone and a display.