Light Emitting Diode having vertical topology and method of making the same

• US 20070295952A1
• Filed: 02/20/2007
• Published: 12/27/2007
• Est. Priority Date: 06/23/2006
• Status: Active Grant

• Current Assignee: Suzhou Lekin Semiconductor Company Limited
• Original Assignee: LG Electronics, Inc. (LG Corporation), LG Innotek Company Limited (LG Corporation)
• Inventors: Jang, Jun Ho, Bae, Duk Kyu, Cho, Hyun Kyong, Park, Jong Kook, Lee, Jeong Soo, Choi, Jae Wan, Kim, Sun Jung
• Granted Patent: US 7,834,374 B2
• Time in Patent Office: Days
• US Class Current: 257/15
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

An LED having vertical topology and a method of making the same is capable of improving a luminous efficiency and reliability, and is also capable of achieving mass productivity. The method includes forming a semiconductor layer on a substrate; forming a first electrode on the semiconductor layer; forming a supporting layer on the first electrode; generating an acoustic stress wave at the interface between the substrate and semiconductor layer, thereby separating the substrate from the semiconductor layer; and forming a second electrode on the semiconductor layer exposed by the separation of the substrate.

Claims

1. A method of making a light emitting diode (LED), comprising:

forming a semiconductor layer on a substrate;

forming a first electrode on the semiconductor layer;

forming a supporting layer on the first electrode;

generating an acoustic stress wave at the interface between the substrate and semiconductor layer, thereby separating the substrate from the semiconductor layer; and

forming a second electrode on the semiconductor layer exposed by the separation of the substrate.

2. The method according to claim 1, further comprising:

forming a trench in the semiconductor layer to thereby create a chip separation region.

3. The method according to claim 1, wherein the first electrode is formed with Ni, W, Ti, Pt, Au, Pd, Cu, Al, Cr, Ag or an alloy of any combination thereof.

4. The method according to claim 1, wherein the step of forming the first electrode includes:

forming a transparent electrode; and

forming a reflective electrode on the transparent electrode.

5. A light emitting diode (LED), comprising:

a plurality of semiconductor layers;

a first electrode disposed on a first surface of the semiconductor layers;

a passivation layer disposed on at least a portion of the first electrode and on at least one side surface of the semiconductor layers;

at least one connection metal layer disposed on at least a portion of the first electrode and the passivation layer;

a second electrode formed on a second surface of the semiconductor layers; and

a supporting layer disposed on the first electrode.

6. The LED according to claim 5, wherein a metal layer is disposed between the passivation layer and the connection metal layer.

7. The LED according to claim 5, wherein the plurality of semiconductor layers include:

an n-type semiconductor layer;

an active layer disposed on the n-type semiconductor layer; and

a p-type semiconductor layer disposed on the active layer.

8. The LED according to claim 5, further comprising:

a current diffusion layer including an InGaN layer or an InGaN/GaN superlattice layer, on the p-type semiconductor layer.

9. The LED according to claim 5, wherein the first electrode includes:

a first metal layer electrically connected to the semiconductor layers;

a diffusion barrier layer disposed on the first metal layer; and

a second metal layer disposed on the diffusion barrier layer.

10. The LED according to claim 9, wherein the first metal layer, the diffusion barrier layer and the second metal layer are formed as a single alloy layer.

11. The LED according to claim 5, wherein the first electrode includes:

a transparent conductive oxide layer (transparent electrode) electrically connected to the semiconductor layers; and

a reflective electrode formed on the transparent conductive oxide layer (transparent electrode).

12. The LED according to claim 11, wherein the reflective electrode is formed with Ag or Al.

13. The LED according to claim 11, wherein the reflective electrode has a thickness of more than 100 Å

.

14. The LED according to claim 11, wherein the reflective electrode includes:

a first metal layer electrically connected to the semiconductor layers;

a diffusion barrier layer disposed on the first metal layer; and

a second metal layer disposed on the diffusion barrier layer.

15. The LED according to claim 14, wherein the first metal layer, the diffusion barrier layer and the second metal layer are formed as a single alloy layer.

16. The LED according to claim 5, wherein the connection metal layer includes:

a first metal layer electrically connected to the first electrode;

a diffusion barrier layer disposed on the first metal layer; and

a second metal layer disposed on the diffusion barrier layer.

17. The LED according to claim 16, wherein the first metal layer, the diffusion barrier layer and the second metal layer are formed as a single alloy layer.

18. The LED according to claim 5, wherein the first electrode is a transparent electrode.

19. The LED according to claim 5, wherein a light-extraction structure is formed on the second surface of the semiconductor layers.

20. The LED according to claim 19, wherein the light-extraction structure is a photonic crystal pattern.

21. The LED according to claim 20, wherein the light-extraction pattern has a period of 0.2 to 2 μ

m.

22. The LED according to claim 20, wherein the pattern is a plurality of hole patterns having a six-fold (60°

) or twelve-fold (30°

) rotational symmetry.

23. The LED according to claim 22, wherein the hole pattern comprises a unit cell having 19 holes, and shares 6 of 19 holes with adjacent unit cells.

24. The LED according to claim 23, wherein 19 holes constituting the unit cell have a distribution having 1 hole in the center of the cell, 6 holes therearound, each being arranged at the same intervals, and 12 holes arranged with the same intervals around 7 holes.

25. The LED according to claim 20, wherein the pattern has a translational symmetry.

26. The LED according to claim 5, further comprising:

a supporting layer having edges for supporting the semiconductor layers via contact with the first electrode, and supporting lateral sides of the semiconductor layers.

27. The LED according to claim 5, wherein the passivation layer is formed with at least one of silicon dioxide (SiO₂), photoresist (PR), SOG and polyimide.

28. A light emitting diode (LED), comprising:

a plurality of semiconductor layers;

a first electrode disposed on a first surface of the semiconductor layers and includes at least two layers;

a light-extraction structure formed on at least a portion of a second surface of the semiconductor layers;

a second electrode disposed on the second surface of the semiconductor layers; and

a supporting layer disposed on the first electrode.

29. The LED according to claim 28, further comprising:

a current diffusion layer disposed between the first surface of the semiconductor layers and the first electrode.

30. The LED according to claim 28, wherein the light-extraction structure is a photonic crystal structure having a plurality of hole patterns, and, where a period of the photonic crystal structure is designated as “

A”

, the diameter of the hole is in the range of 0.1 A to 0.9 A, and the depth of the hole is in the range of 0.1 μ

m up to a thickness of the semiconductor layers disposed on the second surface of the semiconductor layers.

31. A light emitting diode (LED), comprising:

a plurality of semiconductor layers;

a transparent conductive oxide (TCO) layer disposed on a first surface of the semiconductor layers;

a reflective electrode disposed on the TCO layer;

a supporting layer disposed on the reflective electrode; and

a second electrode disposed on a second surface of the semiconductor layers.

32. The LED according to claim 31, further comprising:

a current diffusion layer including an InGaN layer or an InGaN/GaN superlattice layer disposed between the semiconductor layer and transparent conductive oxide layer.

33. A light emitting diode (LED), comprising:

a plurality of semiconductor layers;

passivation layers disposed on at least one surface of the semiconductor layer;

a first electrode disposed on at least a portion of the semiconductor layer and passivation layers, and formed integrally with an ohmic electrode in ohmic contact with the semiconductor layer, and a connection metal layer that is a seed metal layer or a layer for bonding to a metal or a semiconductor;

a second electrode formed on a second surface of the semiconductor layers; and

a supporting layer disposed on the first electrode.