Method of manufacturing light emitting diodes

• US 7,776,637 B2
• Filed: 05/25/2006
• Issued: 08/17/2010
• Est. Priority Date: 05/27/2005
• Status: Active Grant

• Current Assignee: Suzhou Lekin Semiconductor Company Limited
• Original Assignee: LG Electronics, Inc. (LG Corporation), LG Innotek Company Limited (LG Corporation)
• Inventors: Leem, See jong
• Primary Examiner(s): Garber; Charles D
• Assistant Examiner(s): SENE, PAPE A
• Application Number:
  US11/440,021
• Publication Number:
  US 20060270075A1
• Time in Patent Office: 1,545 Days
• Field of Search: 438/22, 438/46, 438/977, 438/795
• US Class Current: 438/46
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/32257 the layer connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: Y10S 438/977 Thinning or removal of substrate

Abstract

A method of manufacturing a light emitting diode, wherein a laser lift-off (LLO) layer and an epi-layer are formed on a nitride semiconductor substrate, and the nitride semiconductor substrate is then separated through a laser lift-off process, thereby improving the characteristics of the epi-layer and enabling to fabricate a high-grade and high-efficiency light emitting diode. Further, the LLO layer thus prepared is removed using a laser beam so that the relatively expensive nitride semiconductor substrate can be re-used, thereby reducing manufacturing costs.

Claims

1. A method of manufacturing a light emitting diode, comprising:

forming a laser lift-off (LLO) layer comprising at least one of GaN, InGaN, AlGaN and InAlGaN on a nitride semiconductor substrate;

forming a first semiconductor layer on the laser lift-off layer;

forming an active layer and a second semiconductor layer on the first semiconductor layer;

bonding a carrier to a surface of the second semiconductor layer;

carrying out a laser lift-off process in which the laser beam is irradiated on the LLO layer through the nitride semiconductor substrate to separate the nitride semiconductor substrate;

forming a metallic support on of the first semiconductor layer on which the nitride semiconductor substrate is separated;

removing the carrier formed on the surface of the second semiconductor layer;

forming a first electrode on the surface of the second semiconductor layer on which the carrier is removed; and

forming a second electrode on the metallic support,

wherein the LLO layer is completely removed by irradiating the laser beam, wherein the carrier comprises any one of a glass substrate, a sapphire substrate, a silicon substrate, a ZnO substrate, and a nitride semiconductor substrate, or a template substrate in which at least one of GaN, InGaN, AlGaN, and AlInGaN is laminated on anyone of a glass substrate, a sapphire substrate, a silicon substrate, a ZnO substrate, and a nitride semiconductor substrate.

2. The method as claimed in claim 1, between the steps of forming the laser lift-off (LLO) layer and of forming the first semiconductor layer on the nitride semiconductor substrate, further comprising forming an undoped semiconductor layer on an upper surface and/or a lower surface of the LLO layer.

3. The method as claimed in claim 1, wherein the LLO layer has a thickness in the range of 1 Å

-3 um.

4. The method as claimed in claim 1, wherein the LLO layer has an energy band gap greater than that of the nitride semiconductor substrate but smaller than that of the active layer.

5. The method as claimed in claim 1, wherein the lager beam has a wavelength shorter than that corresponding to the band gap energy of the LLO layer but longer than that corresponding to the band gap energy of the nitride semiconductor substrate.

6. The method as claimed in claim 1, wherein the first and second semiconductor layers comprise GaN.

7. The method as claimed in claim 1, further comprising forming a UBM layer on the first electrode and forming a reflective layer between the first electrode and the UBM layer, wherein the reflective layer comprises at least one selected from Ag, AI, Pt, Au, Ni, Ti and transmissive conductive oxide or a combination thereof.

8. The method as claimed in claim 1, wherein the nitride semiconductor substrate is one of a GaN, an InGaN, an AIGaN or AllnGaN substrate, or a template substrate in which at least one of GaN, InGaN, AlGaN and AllnGaN is laminated on any one at least one of a sapphire substrate, a silicon substrate, a ZnO substrate and a nitride semiconductor substrate.

9. The method as claimed in claim 8, wherein any one thickness of GaN, InGaN, AlGaN and AlInGaN laminated on the template substrate has a thickness of 0.001-100 um.

10. The method as claimed in claim 7, further comprising bonding a sub-mount to the UBM layer, wherein the sub-mount is fabricated by forming ohmic-contact materials on top and bottom surfaces of a conductive substrate and forming a solder on the ohmic-contact material formed on the top surface of the conductive substrate.

11. The method as claimed in claim 10, wherein the conductive substrate comprises at least any one of Si, AlN, SiC, GaAs, Cu, Wand Mo.

12. The method as claimed in claim 1, wherein the metallic support is formed by anyone method of an electroplating method, an electro less plating method, a CVD method, a sputtering method and an evaporating method.

13. The method as claimed in claim 1, wherein the metallic support has a thickness in the range of 10-400 μ

m.

14. The method as claimed in claim 1, wherein the metallic support comprises at least one selected from a group consisting of Cu, W, Au, Ni, Mo, Pt, AI, Co, Pd, Ag and Ti.

15. The method as claimed in claim 2, wherein a distance between the LLO layer and the nitrite semiconductor substrate is in the range of 1-10 μ

m, when the undoped semiconductor layer is formed on the top of the LLO layer or the bottom of the LLO layer.

16. The method as claimed in claim 1, wherein the carrier is bonded to the surface of the second semiconductor layer using an adhesive substance and is removed from the surface of the second semiconductor layer using an organic solvent.

17. The method as claimed in claim 16, wherein the adhesive substance is photoresist or wax.