Light emitting device and method for manufacturing the same

• US 8,835,957 B2
• Filed: 03/23/2012
• Issued: 09/16/2014
• Est. Priority Date: 03/24/2011
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Noichi, Takuya, Beppu, Suguru
• Primary Examiner(s): Fulk, Steven J
• Application Number:
  US13/429,229
• Publication Number:
  US 20120248483A1
• Time in Patent Office: 907 Days
• Field of Search: 257/98, 257/E33.061, 438/29
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A light emitting device includes a substrate having a conductive portion; a light emitting element having one or more electrodes on a lower surface side thereof, the electrodes being positioned on the conductive portion of the substrate; a phosphor layer disposed on a surface of the light emitting element and on a peripheral surface area of the conductive portion next to the light emitting element; and a reflection layer covering a part of the phosphor layer disposed on the peripheral surface area of the conductive portion.

Claims

1. A light emitting device, comprising:

a substrate;

a conductive portion formed on an upper surface of the substrate;

a light emitting element having one or more electrodes on a lower surface side thereof, the electrodes being positioned on the conductive portion of the substrate;

a phosphor layer, a first portion of which covers a surface of the light emitting element, and a second portion of which covers at least an upper surface of a part of the conductive portion that extends at least partially around a periphery of the light emitting element; and

a reflection layer that covers at least an upper surface of the second portion of the phosphor layer.

2. The light emitting device according to claim 1, wherein an upper surface of the reflection layer is positioned lower than an upper surface of the light emitting element.

3. The light emitting device according to claim 1, wherein the reflection layer further covers an outer side surface of the second portion of the phosphor layer.

4. The light emitting device according to claim 1, wherein:

the conductive portion has an opening surrounding at least a portion of the light emitting element, the substrate being exposed at the opening,

the second portion of the phosphor layer is separated from the first portion of the phosphor layer by the opening, and

the reflective layer further covers an exposed area of the substrate at the opening.

5. The light emitting device according to claim 4, a width of the opening is in a range of 1 μ

m to 500 μ

m.

6. The light emitting device according to claim 1, wherein:

the light emitting element further comprises a luminescent layer, and

an upper surface of the reflection layer is positioned lower than the luminescent layer.

7. The light emitting device according to claim 1, wherein an upper surface of the reflection layer is positioned higher than a lower surface of a semiconductor layer of the light emitting element.

8. The light emitting device according to claim 1, wherein an upper surface of the reflection layer is positioned higher than an upper surface of a semiconductor layer of the light emitting element.

9. The light emitting device according to claim 1, wherein the reflection layer covers an entirety of the second portion of the phosphor layer.

10. The light emitting device according to claim 1, further comprising a covering layer disposed between the light emitting element and the phosphor layer.

11. The light emitting device according to claim 1, wherein all of the electrodes of the light emitting element are formed on the lower surface side of the light emitting element.

12. The light emitting device according to claim 11,

wherein the light emitting element includes an insulating substrate, and

wherein the light emitting device further comprises an insulating covering layer located on the surface of the light emitting element.

13. The light emitting device according to claim 12, wherein the insulating substrate of the light emitting element is made of sapphire.

14. The light emitting device according to claim 1, further comprising a protection element located on the substrate, wherein the reflection layer also covers the protection element.

15. The light emitting device according to claim 1, further comprising a member that includes a lens and a collar section, said member covering the substrate, the reflection layer and the phosphor layer.

16. The light emitting device according to claim 15, wherein a contour of the conductive portion is formed along a contour of the lens.

17. The light emitting device according to claim 1, wherein the phosphor layer has an uniform thickness.

18. The light emitting device according to claim 1, wherein a thickness of the phosphor layer is in a range of about 0.1 μ

m to about 100 μ

m and a thickness of the reflective layer is in a range of about 0.1 μ

m to about 100 μ

m.

19. The light emitting device according to claim 1, wherein the phosphor layer contains a nitride-based phosphor that is activated by a lanthanoid-based element or a rare earth alminate, and rare earth silicate phosphor that is activated by a lanthanoid-based element.

20. The light emitting device according to claim 1, wherein the phosphor layer contains YAG-based phosphor.

21. The light emitting device according to claim 20, wherein the phosphor layer contains phosphor particles, and the average particle diameter of the phosphor particles is more than 8 μ

m.

22. The light emitting device according to claim 1, the reflection layer reflects the light emitted from the light emitting element more than 90% in its peak wavelength.

23. The light emitting device according to claim 22, the reflecting layer contains particles of material selected from the group consisting SiO₂, TiO₂, ZrO₂, BaSO₄, and MgO.

24. A method for manufacturing a light emitting device, the method comprising:

connecting one or more electrodes of a light emitting element to a conductive portion formed on a substrate;

forming a phosphor layer such that a first portion of the phosphor layer covers a surface of the light emitting element, and a second portion of the phosphor layer covers at least an upper surface of a part of the conductive portion that extends at least partially around a periphery of the light emitting element; and

forming a reflection layer that covers at least an upper surface of the second portion of the phosphor layer.

25. The method for manufacturing the light emitting device according to claim 24, wherein:

the phosphor layer is formed such that the first portion of the phosphor layer contacts the surface of the light emitting element and the second portion of the phosphor layer contacts the upper surface of the part of the conductive portion that extends at least partially around the periphery of the light emitting element.

26. The method for manufacturing the light emitting device according to claim 24, wherein the phosphor layer is formed by an electrodeposition method or an electrostatic coating method.

27. The method for manufacturing the light emitting device according to claim 24, wherein the reflection layer is formed by an electrodeposition method or an electrostatic coating method.

28. The method for manufacturing the light emitting device according to claim 27, further comprising:

forming a covering layer having conductivity on the surface of the light emitting element before forming the phosphor layer, wherein the phosphor layer is formed such that the first portion of the phosphor layer contacts a surface of the covering layer and the second portion of the phosphor layer contacts the upper surface of the part of the conductive portion that extends at least partially around the periphery of the light emitting element; and

reforming the covering layer so as to have an insulating property after forming the phosphor layer.

29. The method according to claim 24, wherein an upper surface of the reflection layer is positioned lower than an upper surface of the light emitting element.

30. The method according to claim 24, wherein the reflection layer is formed so as to further cover an outer side surface of the second portion of the phosphor layer.

31. The method according to claim 24, wherein:

the conductive portion has an opening surrounding at least a portion of the light emitting element, the substrate being exposed at the opening,

the second portion of the phosphor layer is separated from the first portion of the phosphor layer by the opening, and

the reflective layer is formed so as to further cover an exposed area of the substrate at the opening.

32. The method according to claim 24, wherein:

the light emitting element further comprises a luminescent layer, and

an upper surface of the reflection layer is positioned lower than the luminescent layer.

33. The method according to claim 24, wherein an upper surface of the reflection layer is positioned higher than a lower surface of a semiconductor layer of the light emitting element.

34. The method according to claim 24, wherein an upper surface of the reflection layer is positioned higher than an upper surface of a semiconductor layer of the light emitting element.

35. The method according to claim 24, wherein the reflection layer is formed so as to cover an entirety of the second portion of the phosphor layer.

36. The method according to claim 24, wherein both the phosphor layer and the reflection layer are formed by an electrodeposition method or an electrostatic coating method.

37. The method according to claim 24, wherein all of the electrodes of the light emitting element are formed on the lower surface side of the light emitting element.

38. A method for manufacturing a light emitting device, the method comprising:

connecting one or more electrodes of a light emitting element to a conductive portion of a substrate;

forming a covering layer having conductivity on the surface of the light emitting element;

forming a phosphor layer on at least the light emitting element on the substrate, the phosphor layer being formed on a surface of the covering layer and on a peripheral surface area of the conductive portion next to the light emitting element;

reforming the covering layer so as to have an insulating property after forming the phosphor layer; and

forming a reflection layer on a part of the phosphor layer around a periphery of the light emitting element.

39. The method according to claim 38, wherein both the phosphor layer and the reflection layer are formed by an electrodeposition method or an electrostatic coating method.

40. The method according to claim 39, wherein the phosphor layer contains YAG-based phosphor particles.

41. The method according to claim 38, wherein the cover layer is reformed by oxidation treatment.