Light emitting device and method of manufacturing the same

• US 8,021,204 B2
• Filed: 08/10/2009
• Issued: 09/20/2011
• Est. Priority Date: 04/23/2002
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kuwabara, Hideaki, Seo, Satoshi, Yamazaki, Shunpei
• Primary Examiner(s): Ton; Toan
• Assistant Examiner(s): Snyder; Zachary
• Application Number:
  US12/538,563
• Publication Number:
  US 20090298377A1
• Time in Patent Office: 771 Days
• Field of Search: 313498-512, 445/23, 445/24, 445/46, 445/49
• US Class Current: 445/24
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/813 characterised by their shape
• CPC Class Codes: H10K 50/818 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 50/82 Cathodes
• CPC Class Codes: H10K 50/824 combined with auxiliary electrodes
• CPC Class Codes: H10K 50/828 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 50/84 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/841 Self-supporting sealing arrangements
• CPC Class Codes: H10K 50/844 Encapsulations
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 59/122 Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 59/30 Devices specially adapted for multicolour light emission
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]
• CPC Class Codes: H10K 59/80515 characterised by their shape
• CPC Class Codes: H10K 59/80518 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 59/80522 combined with auxiliary electrodes
• CPC Class Codes: H10K 59/80524 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 59/871 Self-supporting sealing arrangements
• CPC Class Codes: H10K 59/873 Encapsulations
• CPC Class Codes: H10K 59/878 : comprising reflective means

Abstract

All lights generated in an organic compound layer are not taken out towards a TFT from a cathode as a transparent electrode. For instance, the light is emitted in a lateral direction (direction parallel to the substrate surface) but the light emitted in the lateral direction is not taken out resultantly, which leads to a loss. Therefore, a light emitting device structured so as to increase the amount of light taken out in a certain direction is provided as well as a method of manufacturing this light emitting device. As a result of etching treatment, an upper edge portion of an insulator (19) is curved to have a radius of curvature, a slope is formed along the curved face while partially exposing layers (18c and 18d) of a first electrode, and a layer (18b) of the first electrode is exposed in a region that serves as a light emitting region. Light emitted from an organic compound layer (20) is reflected by the slope of the first electrode (layers 18c and 18d) to increase the total amount of light taken out in the direction indicated by the arrow in FIG. 1A.

Claims

1. A method of manufacturing a light emitting device comprising:

forming a first electrode which is a laminate of metal layers and is electrically connected to a thin film transistor over a substrate having an insulating surface;

forming an insulator to cover an edge portion of the first electrode;

thinning the first electrode so that the first electrode has a depression having a sloped surface by etching using the insulator as a mask;

forming a layer containing an organic compound on and in direct contact with the sloped surface; and

forming a second electrode on the layer containing the organic compound.

2. The method of manufacturing a light emitting device according to claim 1, wherein the first electrode is a laminate of a metal layer reflecting light and a metal layer serving as an etching stopper and that the metal layer reflecting light is etched to expose a metal material that reflects light in the sloped surface.

3. The method of manufacturing a light emitting device according to claim 1, wherein the first electrode is an anode and comprises a metal layer that is larger in a work function than the second electrode.

4. The method of manufacturing a light emitting device according to claim 1, wherein the first electrode is a laminate of a first metal layer containing titanium, a second metal layer containing titanium nitride or tungsten nitride, a third metal layer containing aluminum, and a fourth metal layer containing titanium nitride.

5. The method of manufacturing a light emitting device according to claim 1, wherein an angle of inclination of the sloped surface is more than 30°

and less than 70°

.

6. The method of manufacturing a light emitting device according to claim 1, wherein an upper edge portion of the insulator for covering the edge portion of the first electrode is curved to have a radius of curvature and the radius of curvature is set to 0.2 to 3 μ

m.

7. The method of manufacturing a light emitting device according to claim 1, wherein the second electrode comprises a thin metal film that transmits light.

8. A method of manufacturing a light emitting device comprising:

forming a first electrode which is a laminate of metal layers and is electrically connected to a thin film transistor over a substrate having an insulating surface;

forming an insulator to cover an edge portion of the first electrode;

thinning the first electrode so that the first electrode has depression having a sloped surface by etching using the insulator as a mask, and so that a number of layers of the laminate of metal layers in the depression is smaller than the number of layers of the laminate of metal layers outside the depression;

forming a layer containing an organic compound on and in direct contact with the sloped surface; and

forming a second electrode on the layer containing the organic compound.

9. The method of manufacturing a light emitting device according to claim 8, wherein the first electrode is a laminate of a metal layer reflecting light and a metal layer serving as an etching stopper and that the metal layer reflecting light is etched to expose a metal material that reflects light in the sloped surface.

10. The method of manufacturing a light emitting device according to claim 8, wherein the first electrode is an anode and comprises a metal layer that is larger in a work function than the second electrode.

11. The method of manufacturing a light emitting device according to claim 8, wherein the first electrode is a laminate of a first metal layer containing titanium, a second metal layer containing titanium nitride or tungsten nitride, a third metal layer containing aluminum, and a fourth metal layer containing titanium nitride.

12. The method of manufacturing a light emitting device according to claim 8, wherein an angle of inclination of the sloped surface is more than 30°

and less than 70°

.

13. The method of manufacturing a light emitting device according to claim 8, wherein an upper edge portion of the insulator for covering the edge portion of the first electrode is curved to have a radius of curvature and the radius of curvature is set to 0.2 to 3 μ

m.

14. The method of manufacturing a light emitting device according to claim 8, wherein the second electrode comprises a thin metal film that transmits light.

15. A method of manufacturing a light emitting device comprising:

forming a first electrode which is a laminate of metal layers and is electrically connected to a thin film transistor over a substrate having an insulating surface;

forming an insulator to cover an edge portion of the first electrode;

thinning the first electrode so that the first electrode has a depression having a sloped surface by etching using the insulator as a mask;

forming a layer containing an organic compound on and in direct contact with the sloped surface;

forming a second electrode on the layer containing the organic compound; and

raising a work function of the first electrode or the second electrode.

16. The method of manufacturing a light emitting device according to claim 15, wherein the first electrode is a laminate of a metal layer reflecting light and a metal layer serving as an etching stopper and that the metal layer reflecting light is etched to expose a metal material that reflects light in the sloped surface.

17. The method of manufacturing a light emitting device according to claim 15, wherein the first electrode is an anode and comprises a metal layer that is larger in a work function than the second electrode.

18. The method of manufacturing a light emitting device according to claim 15, wherein the first electrode is a laminate of a first metal layer containing titanium, a second metal layer containing titanium nitride or tungsten nitride, a third metal layer containing aluminum, and a fourth metal layer containing titanium nitride.

19. The method of manufacturing a light emitting device according to claim 15, wherein an angle of inclination of the sloped surface is more than 30°

and less than 70°

.

20. The method of manufacturing a light emitting device according to claim 15, wherein an upper edge portion of the insulator for covering the edge portion of the first electrode is curved to have a radius of curvature and the radius of curvature is set to 0.2 to 3 μ

m.

21. The method of manufacturing a light emitting device according to claim 15, wherein the second electrode comprises a thin metal film that transmits light.

22. The method of manufacturing a light emitting device according to claim 15, wherein the step of raising the work function is performed by a UV-ozone treatment.

23. A method of manufacturing a light emitting device comprising:

forming a first electrode which is a laminate of metal layers and is electrically connected to a thin film transistor over a substrate having an insulating surface;

forming an insulator to cover an edge portion of the first electrode;

thinning the first electrode so that the first electrode has depression having a sloped surface by etching using the insulator as a mask, and so that a number of layers of the laminate of metal layers in the depression is smaller than the number of layers of the laminate of metal layers outside the depression;

forming a layer containing an organic compound on and in direct contact with the sloped surface;

forming a second electrode on the layer containing the organic compound; and

raising a work function of the first electrode or the second electrode.

24. The method of manufacturing a light emitting device according to claim 23, wherein the first electrode is a laminate of a metal layer reflecting light and a metal layer serving as an etching stopper and that the metal layer reflecting light is etched to expose a metal material that reflects light in the sloped surface.

25. The method of manufacturing a light emitting device according to claim 23, wherein the first electrode is an anode and comprises a metal layer that is larger in a work function than the second electrode.

26. The method of manufacturing a light emitting device according to claim 23, wherein the first electrode is a laminate of a first metal layer containing titanium, a second metal layer containing titanium nitride or tungsten nitride, a third metal layer containing aluminum, and a fourth metal layer containing titanium nitride.

27. The method of manufacturing a light emitting device according to claim 23, wherein an angle of inclination of the sloped surface is more than 30°

and less than 70°

.

28. The method of manufacturing a light emitting device according to claim 23, wherein an upper edge portion of the insulator for covering the edge portion of the first electrode is curved to have a radius of curvature and the radius of curvature is set to 0.2 to 3 μ

m.

29. The method of manufacturing a light emitting device according to claim 23, wherein the second electrode comprises a thin metal film that transmits light.

30. The method of manufacturing a light emitting device according to claim 23, wherein the step of raising the work function is performed by a UV-ozone treatment.