WHITE FLIP CHIP LIGHT EMITTING DIODE (FC LED) AND FABRICATION METHOD

• US 20150280078A1
• Filed: 03/31/2014
• Published: 10/01/2015
• Est. Priority Date: 03/31/2014
• Status: Abandoned Application

• Current Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Original Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Inventors: YEN, JUI-KANG, CHEN, YUNG-WEI, CHEN, CHIH-HSUN
• Application Number:
  US14/230,040
• Publication Number:
  US 20150280078A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

A white flip chip light emitting diode (FC LED) includes a flip chip (LED) die configured to emit electromagnetic radiation; reflective sidewalls on the (LED) die; and a wavelength conversion member having a uniform thickness and a surface area greater than or equal to a footprint of the flip chip (LED) die configured to change a wavelength of the electromagnetic radiation to produce white light. A method for fabricating the white flip chip light emitting diode (FC LED) includes the steps of: providing the flip chip (LED) die; forming reflective sidewalls on the flip chip (LED) die; and forming a wavelength conversion member on the flip chip (LED) die.

Claims

1. A method for fabricating a white flip chip light emitting diode (FC LED) comprising:

providing a flip chip (LED) die comprising a sapphire substrate having a planar surface and a plurality of sides, an n-type confinement layer on the sapphire substrate, a multiple quantum well (MQW) layer on the n-type confinement layer configured to emit electromagnetic radiation, and a p-type confinement layer on the multiple quantum well (MQW) layer;

forming reflective sidewalls on the sides of the sapphire substrate configured to prevent the electromagnetic radiation from transmitting through the sides; and

forming a wavelength conversion member on the planar surface of the sapphire substrate having a uniform thickness and an area equal to or greater than an area of the planar surface configured to change a wavelength of the electromagnetic radiation to produce white light.

2. The method of claim 1 wherein the forming the reflective sidewalls step comprises forming a backside polymer film on a backside of the flip chip (LED) die, forming an emitter side polymer film on the planar surface of the sapphire substrate, and then depositing a reflective metal on the sides of the sapphire substrate.

3. The method of claim 2 wherein the forming the wavelength conversion member comprises removing the emitter side polymer film and attaching a pre-fabricated wavelength conversion member to planar surface of the sapphire substrate.

4. The method of claim 3 wherein the forming the reflective sidewalls step comprises depositing an electrically insulating isolation layer on the sides of the sapphire substrate and then depositing the reflective metal on the isolation layer.

5. The method of claim 4 wherein the forming the reflective sidewalls step further comprises forming a protective layer on an outside surface of the reflective metal.

6. The method of claim 5 further comprising forming a lens on the wavelength conversion member.

7. The method of claim 6 further comprising providing an n-pad on the flip chip (LED) die in electrical contact with the n-type confinement layer and a p-pad on the flip chip (LED) die in electrical contact with the p-type confinement layer and wherein the backside polymer film covers the n-pad and the p-pad during the forming the reflective sidewalls step.

8. A method for fabricating a white flip chip light emitting diode (FC LED) comprising:

providing a flip chip (LED) die having an emitter side, a backside, and a footprint, the flip chip (LED) die comprising a sapphire substrate having a planar surface proximate to the emitter side, a plurality of vertical sides, and an epitaxial structure on the sapphire substrate, the epitaxial structure comprising an n-type confinement layer on the sapphire substrate, a multiple quantum well (MQW) layer on the n-type confinement layer configured to emit electromagnetic radiation, and a p-type confinement layer on the multiple quantum well (MQW) layer;

forming a backside polymer film on the backside of the flip chip (LED) die configured to cover the epitaxial structure while leaving the side of the sapphire substrate exposed;

forming an emitter side polymer film on the planar surface of the sapphire substrate configured to leave the sides exposed;

forming reflective sidewalls on the sides of the sapphire substrate using the backside polymer film to protect the epitaxial structure and the emitter side polymer film to protect the planar surface of the sapphire substrate;

removing the emitter side polymer film to expose the planar surface of the sapphire substrate;

forming a wavelength conversion member on the planar surface of the sapphire substrate having a uniform thickness and a surface area greater than or equal to the footprint of the flip chip (LED) die configured to change a wavelength of the electromagnetic radiation to produce white light; and

removing the backside polymer film.

9. The method of claim 8 wherein the forming the wavelength conversion member step comprises attaching a pre-fabricated wavelength conversion member to the sapphire substrate.

10. The method of claim 8 wherein the forming the reflective sidewalls step forms the reflective sidewalls on the sides of the sapphire substrate but not on the epitaxial structure.

11. The method of claim 8 wherein the emitter side polymer film comprises a pressure sensitive adhesive (PSA) tape having a thermal release and the removing the emitter side polymer film step comprises heating the (PSA) tape.

12. The method of claim 8 wherein the forming the reflective sidewalls step comprises a method selected from the group consisting of electro-deposition, electroless-deposition, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), evaporation, and plasma spray.

13. The method of claim 8 wherein the forming the reflective sidewalls step comprises depositing an electrically insulating isolation layer on the sides of the sapphire substrate and then depositing a reflective metal on the isolation layer.

14. The method of claim 8 wherein the forming the reflective sidewalls step further comprises forming a protective layer an outside surface thereof.

15. The method of claim 8 further comprising flip chip mounting the flip chip (LED) die to a module substrate.

16. The method of claim 8 wherein the reflective sidewalls comprise a metal selected from the group consisting of Ag, Al, Au, Cr, Pt, Pd and alloys thereof.

17. The method of claim 8 further comprising forming a lens on the wavelength conversion member.

18. A white flip chip light emitting diode (FC LED) comprising:

a flip chip (LED) die having an emitter side, a backside, and a footprint, the flip chip (LED) die comprising a sapphire substrate having a planar surface proximate to the emitter side, a plurality of vertical sides, and an epitaxial structure on the sapphire substrate, the epitaxial structure comprising an n-type confinement layer on the sapphire substrate, a multiple quantum well (MQW) layer on the n-type confinement layer configured to emit electromagnetic radiation, and a p-type confinement layer on the multiple quantum well (MQW) layer;

a plurality of reflective sidewalls on the sides of the sapphire substrate comprising a metal configured to prevent transmission of the electromagnetic radiation through the sides; and

a wavelength conversion member on the planar surface of the sapphire substrate having a uniform thickness and a surface area greater than or equal to the footprint of the flip chip (LED) die configured to change a wavelength of the electromagnetic radiation to produce white light.

19. The white flip chip light emitting diode (FC LED) of claim 18 further comprising an n-pad on the backside of the flip chip (LED) die in electrical communication with the n-type confinement layer and a p-pad on the backside of the flip chip (LED) die in electrical communication with the p-type confinement layer.

20. The white flip chip light emitting diode (FC LED) of claim 18 further comprising a lens on the wavelength conversion member.

21. The white flip chip light emitting diode (FC LED) of claim 18 wherein the reflective sidewalls comprise a metal selected from the group consisting of Ag, Al, Au, Cr, Pt, Pd and alloys thereof.

22. The white flip chip light emitting diode (FC LED) of claim 18 wherein the reflective sidewalls comprise a metal and an electrically insulating isolation layer between the metal and the sides of the sapphire substrate.

23. The white flip chip light emitting diode (FC LED) of claim 18 wherein the reflective sidewalls comprise a metal, an electrically insulating isolation layer between the metal and the sides of the sapphire substrate, and a protective layer on an outside surface of the metal.

24. The white flip chip light emitting diode (FC LED) of claim 18 wherein the wavelength conversion member comprises a pre-fabricated sheet attached to the sapphire substrate.

25. The white flip chip light emitting diode (FC LED) of claim 18 further comprising a module substrate having a plurality of electrodes bonded to the n-pad and the p-pad configured to form a (LED) system.