LEDs using single crystalline phosphor and methods of fabricating same

• US 7,859,000 B2
• Filed: 04/10/2008
• Issued: 12/28/2010
• Est. Priority Date: 04/10/2008
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Chakraborty, Arpan
• Primary Examiner(s): Mandala; Victor A
• Application Number:
  US12/082,444
• Publication Number:
  US 20090256163A1
• Time in Patent Office: 992 Days
• Field of Search: 257/79, 257/94, 257/98, 257/E33.06, 257/E33.061
• US Class Current: 257/98
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/502 Wavelength conversion materials

Abstract

Methods for fabricating LED chips from a wafer and devices fabricated using the methods with one method comprising depositing LED epitaxial layers on an LED growth wafer to form a plurality of LEDs on the growth wafer. A single crystalline phosphor is bonded over at least some the plurality of LEDs so that at least some light from the covered LEDs passes through the single crystalline phosphor and is converted. The LED chips can then be singulated from the wafer to provide LED chips each having a portion of said single crystalline phosphor to convert LED light.

Claims

1. A light emitting diode (LED) chip, comprising:

an LED comprising;

an n-type layer;

a p-type layer; and

an active region interposed between and in direct contact with said n-type layer and said p-type layer; and

a single crystalline phosphor in direct contact with and at least partially covering said LED at least one of said n-type layer or p-type layer so that at least some of the light emitted by said LED is converted by said single crystalline phosphor.

2. The LED chip of claim 1, wherein said LED chip emits a combination of light from said LED and from said single crystalline phosphor.

3. The LED chip of claim 1, wherein said single crystalline phosphor is bonded to said n-type layer.

4. The LED chip of claim 1, wherein said single crystalline phosphor provides mechanical support for said LED.

5. The LED chip of claim 1, emitting a white light combination of light from said LED and converted light from said single crystalline phosphor.

6. The LED chip of claim 1, wherein said single crystalline phosphor comprises yttrium aluminum garnet (YAG).

7. The LED chip of claim 1, wherein said single crystalline phosphor further comprises a phosphor material.

8. The LED chip of claim 1, wherein said single crystalline substrate further comprises a phosphor to absorb light from said LED and emit downconverted light.

9. The LED chip of claim 8, where said downconverted light is green or yellow.

10. The LED chip of claim 8, wherein said downconverted light is orange or red.

11. The LED chip of claim 1, further comprise contacts with said single crystalline phosphor comprises openings to at least one of said contacts.

12. The LED chip of claim 1, wherein said LEDs have lateral geometry and first and second contacts accessible from one surface.

13. The LED chip of claim 12, wherein said single crystalline phosphor covers said LEDs on a surface opposite the surface from which said contacts are accessed.

14. The LED chip of claim 1, further comprising covering a least some of said LED with a second single crystalline phosphor.

15. The LED chip of claim 1, further comprising a high reflectivity mirror on said LED opposite to the said single crystalline.

16. A light emitting diode (LED) package comprising:

an LED chip, comprising an LED and a single crystalline phosphor at least partially covering said LED and converting at least some of the light from said LED, and first and second contacts for applying an electrical signal to said LED;

package leads in electrical connection with said first and second contacts; and

encapsulation surrounding said LED chip and electrical connections.

17. The LED package of claim 16, further comprising light scattering particles in said encapsulation.

18. The LED package of claim 16, wherein said single crystalline phosphor comprises a phosphor material, and the concentration of said phosphor material is graded in said single crystalline phosphor.

19. The LED package of claim 18, wherein said single crystalline phosphor further comprises scattering particles.

20. The LED package of claim 16, wherein the surface of said encapsulation is textured.