Phosphor with laminated coating, its manufacture method and light emitting device using same

• US 20060255713A1
• Filed: 03/22/2006
• Published: 11/16/2006
• Est. Priority Date: 03/23/2005
• Status: Active Grant

• Current Assignee: Stanley Electric Company Limited
• Original Assignee: Stanley Electric Company Limited
• Inventors: Kondo, Kenichi, Taya, Shuichi
• Granted Patent: US 7,795,797 B2
• Time in Patent Office: Days
• US Class Current: 313/486
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/85385 Shape, e.g. interlocking features
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

A phosphor made of phosphor particles coated with inorganic substance lamination, wherein an outermost layer is a transparent layer made of one or more of SiO₂, Al₂O₃ and SiON, having a thickness of about 10 nm to about 500 nm, and formed by fluidized bed CVD, and a transparent inner coating layer is formed inside the outermost layer by a method different from the fluidized bed CVD. The inner coating may be formed by nonaqueous method not using a water content, for example sintering super-fine particles distributed on phosphor particles.

Claims

1. A phosphor made of phosphor particles coated with inorganic substance lamination, the lamination comprising:

an inner coating layer that is relatively thin and transparent, formed by a first film forming method and coated on said phosphor particle; and

an outer coating layer that is relatively thick and transparent, made of one or more of SiO₂, Al₂O₃ and SiON, having a thickness of about 10 nm to about 500 nm, formed by a second film forming method different from said first film forming method and coated over an outer surface of said phosphor particle having said inner coating layer thereon.

2. The phosphor according to claim 1, wherein said second film forming method is fluidized bed CVD.

3. The phosphor according to claim 1, wherein said first film forming method is a nonaqueous method not using a water content.

4. The phosphor according to claim 3, wherein said first film forming method comprises sintering nanometer size super-fine particles dispersed on phosphor particles.

5. The phosphor according to claim 3, wherein said inner coating layer includes at least one of TiO₂, Al₂O₃, SiO₂ and SiON.

6. The phosphor according to claim 1, wherein said phosphor particles include at least one of Sr_1-xCa_xS:

Eu and Sr_1-xCa_xGa₂S₄;

Eu.

7. A light emitting device comprising:

a blue or ultraviolet light emitting diode; and

a host element containing a phosphor, over the light emitting diode, wherein said phosphor is made of phosphor particles coated with inorganic substance lamination, the lamination comprising;

an inner coating layer that is relatively thin and transparent, formed by a first film forming method and coated on said phosphor particle; and

an outer coating layer that is relatively thick and transparent, made of one or more of SiO₂, Al₂O₃ and SiON, having a thickness of about 10 nm to about 500 nm, formed by a second film forming method and coated over an outer surface of said phosphor particle having said inner coating layer thereon.

8. The light emitting device according to claim 7, wherein said second film forming method is fluidized bed CVD.

9. The light emitting device according to claim 7, wherein said first film forming method is a nonaqueous method not using a water content.

10. The light emitting device according to claim 9, wherein said first film forming method comprises sintering nanometer size super-fine particles dispersed on phosphor particles.

11. The light emitting device according to claim 9, wherein said inner coating layer includes at least one of TiO₂, Al₂O₃, SiO₂ and SiON.

12. The light emitting device according to claim 7, wherein said phosphor particles include phosphor particles made of Sr_1-xCa_xS:

Eu and phosphor particles made of Sr_1-xCa_xGa₂S₄;

Eu.

13. The light emitting device according to claim 12, wherein said phosphor is mixed in said host element at a weight percent between about 3 wt % and about 7 wt %.

14. The light emitting device according to claim 13, wherein a weight ratio between said phosphor particles made of Sr_1-xCa_xS:

Eu and said phosphor particles made of Sr_1-xCa_xGa₂S₄;

Eu is within about 60;

40 to about 80;

20.

15. The light emitting device according to claim 7, further comprising:

a package comprising a support substrate made of silicon and having a recess with a bottom surface and slanted side surfaces, an oxide film formed on a surface of said support substrate, and a pair of reflecting-electrodes formed on the oxide film in the recess and electrically separated by each other,

wherein said light emitting diode is bonded to one of the pair of reflecting electrodes in the recess, and the phosphor contains Sr_1-xCa_xS;

Eu and Sr_1-xCa_xGa₂S₄;

Eu, and

wherein said host element includes an organic resin and fills the recess over the light emitting diode.

16. A method of manufacturing a phosphor, comprising:

forming an inner coating layer that is relatively thin and transparent by a first film forming method on phosphor particles; and

forming an outer coating layer that is relatively thick and transparent made of one or more of inorganic substances SiO₂, Al₂O₃ and SiON and having a thickness of about 10 nm to about 500 nm, by a second film forming method different from said first film forming method, over said phosphor particles having said inner coating layer thereon.

17. The method according to claim 16, wherein said second film forming method is fluidized bed CVD.

18. The method according to claim 16, wherein said first film forming method is a nonaqueous method not using a water content.

19. The method according to claim 18, wherein said first film forming method comprises sintering nanometer size super-fine particles dispersed on phosphor particles.

20. The method according to claim 16, wherein said inner coating layer includes at least one of TiO₂, Al₂O₃, SiO₂ and SiON.

21. The method according to claim 16, wherein said phosphor particles include at least one of Sr_1-xCa_xS:

Eu and Sr_1-xCa_xGa₂S₄;

Eu.

22. The method according to claim 16, further comprising forming an intermediate coating layer on the inner coating layer by a sol-gel method before forming the outer coating layer.

23. A light conversion material, comprising:

light conversion particles that convert light of a first spectrum to light of a second spectrum;

for each of the light conversion particles, a first layer covering a substantially entire surface of the light conversion particle; and

for each of the light conversion particles, a second layer covering a substantially entire surface of the first layer.

24. The light conversion material according to claim 23, wherein the light conversion particles include at least one of Sr_1-xCa_xS:

Eu and Sr_1-xCa_xGa₂S₄;

Eu,

wherein the first layer is a substantially water-free and substantially HCL-free inorganic layer including at least one of TiO₂, Al₂O₃, SiO₂ and SiON, and

wherein the second layer is a substantially water-free inorganic layer including at least one of Al₂O₃, SiO₂ and SiON.

25. The light conversion material according to claim 23, further comprising, for each of the light conversion particles, a third layer between the first layer and the second layer.

26. A light emitting device, comprising:

a light emitting diode for emitting light of a first spectrum; and

a host element over the light emitting diode, the host element including a light conversion element

wherein a light conversion element includes;

light conversion particles that convert said light of the first spectrum to light of a second spectrum;

for each of the light conversion particles, a first layer covering a substantially entire surface of the light conversion particle; and

for each of the light conversion particles, a second layer covering a substantially entire surface of the first layer.

27. The light emitting device according to claim 26, wherein the light conversion particles include at least one of Sr_1-xCa_xS:

Eu and Sr_1-xCa_xGa₂S₄;

Eu,

wherein the first layer is a substantially water-free and substantially HCL-free inorganic layer including at least one of TiO₂, Al₂O₃, SiO₂ and SiON, and

wherein the second layer is a substantially water-free inorganic layer including at least one of Al₂O₃, SiO₂ and SiON.

28. The light emitting device according to claim 26, further comprising, for each of the light conversion particles, a third layer between the first layer and the second layer.