LIGHT EMITTING DIODE AND METHOD OF MANUFACTURING THE SAME

• US 20150200334A1
• Filed: 03/27/2015
• Published: 07/16/2015
• Est. Priority Date: 09/16/2011
• Status: Active Grant

• Current Assignee: Seoul Viosys Co., Ltd. (Seoul Semiconductor Co., Ltd.)
• Original Assignee: Seoul Viosys Co., Ltd. (Seoul Semiconductor Co., Ltd.)
• Inventors: Chae, Jong Hyeon, Jang, Jong Min, Roh, Won Young, Suh, Daewoong, Cho, Dae Sung, Lee, Joon Sup, Lee, Kyu Ho, In, Chi Hyun
• Granted Patent: US 9,634,193 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/1403 Bump connectors having different sizes, e.g. different diameters, heights or widths
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• 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 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• 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 light-emitting diode including a substrate, a first semiconductor layer disposed on the substrate, an active layer disposed on the first semiconductor layer, a second semiconductor layer disposed on the active layer and having a conductivity type different than that of the first semiconductor layer, and a reflective pattern disposed on the second semiconductor layer and configured to reflect light emitted from the active layer, the reflective pattern having heterogeneous metal layers and configured to absorb stress caused by differences in coefficient of thermal expansion between the heterogeneous metal layers.

Claims

1. A light-emitting diode, comprising:

a substrate;

a first semiconductor layer disposed on the substrate;

an active layer disposed on the first semiconductor layer;

a second semiconductor layer disposed on the active layer and having a conductivity type a different than that of the first semiconductor layer; and

a reflective pattern disposed on the second semiconductor layer and configured to reflect light emitted from the active layer, the reflective pattern comprising heterogeneous metal layers and configured to absorb stress caused by differences in coefficient of thermal expansion between the heterogeneous metal layers.

2. The light-emitting diode according to claim 1, wherein the substrate comprises a pattern of depressions recessed from a surface thereof.

3. The light-emitting diode according to claim 2, wherein the depressions have at least one of a semi-spherical shape, a triangular shape, and a trapezoidal shape.

4. The light-emitting diode according to claim 2, further comprising:

an anti-reflective layer disposed on the substrate between the pattern of depressions.

5. The light-emitting diode according to claim 1, wherein the reflective pattern comprises:

a reflective metal layer disposed on the second semiconductor layer;

a conductive barrier layer disposed on the reflective metal layer; and

a stress relief layer disposed between the reflective metal layer and the conductive barrier a layer, the stress relief layer configured to absorb stress caused by differences in the coefficient of thermal expansion of the reflective metal layer and the conductive barrier layer,

wherein the conductive barrier layer covers side surfaces of the reflective metal layer and the stress relief layer.

6. The light-emitting diode according to claim 5, wherein the coefficient of thermal expansion of the stress relief layer is greater than or equal to that of the conductive barrier layer and is less than or equal to that of the reflective metal layer.

7. The light-emitting diode according to claim 5, wherein the reflective metal layer comprises at least one of Al, Al alloys, Ag, and Ag alloys.

8. The light-emitting diode according to claim 7, wherein the conductive barrier layer comprises at least one of W, TiW, Mo, Ti, Cr, Pt, Rh, Pd, and Ni.

9. The light-emitting diode according to claim 8, wherein the reflective metal layer comprises Al or an Al alloy and the conductive barrier layer comprises at least one of W, TiW and Mo, and the stress relief layer comprises a single layer comprising one of Ag, Cu, Ni, Pt, Ti, Rh, Pd and Cr, or a composite layer comprising at least one of Cu, Ni, Pt, Ti, Rh, Pd and Au.

10. The light-emitting diode according to claim 8, wherein the reflective metal layer comprises Al or an Al alloy and the conductive barrier layer comprises at least one of Ti, Cr, Pt, Rh, Pd and Ni, and the stress relief layer comprises a single layer comprising Ag or Cu, or a composite layer comprising at least one of Ni, Au, Cu and Ag.

11. The light-emitting diode according to claim 8, wherein the reflective metal layer comprises Ag or an Ag alloy and the conductive barrier layer comprises at least one of W, TiW and Mo, and the stress relief layer comprises a single layer comprising one of Cu, Ni, Pt, Ti, Rh, Pd and Cr, or a composite layer comprising at least one of Cu, Ni, Pt, Ti, Rh, Pd, Cr and Au.

12. The light-emitting diode according to claim 8, wherein the reflective metal layer comprises Ag or an Ag alloy and the conductive barrier layer comprises Pt or Ni, and the stress relief layer comprises a single layer comprising one of Cu, Cr, Rh, Pd, TiW and Ti, or a composite layer comprising at least one of Ni, Au and Cu.

13. The light-emitting diode according to claim 5, wherein the reflective pattern further comprises an ohmic bonding layer disposed between the reflective metal layer and the second semiconductor layer.

14. The light-emitting diode according to claim 13, wherein the ohmic bonding layer comprises at least one of Ni, Pt, ITO and ZnO.

15. The light-emitting diode according to claim 1, wherein a lateral profile of the active layer and the second semiconductor layer has an inclination of 20 to 70 degrees with respect to a surface of the first semiconductor layer.

16. A method of fabricating a light emitting diode, the method comprising:

sequentially forming a first semiconductor layer, an active layer, and a second semiconductor layer on a substrate;

forming a mesa area by etching the second semiconductor layer and the active layer such that a surface of the first semiconductor layer is exposed through the mesa area; and

forming a reflective pattern on the second semiconductor layer, the reflective pattern configured to reflect light emitted from the active layer and comprising heterogeneous metal layers configured to absorb stress caused by differences in coefficient of thermal expansion between the heterogeneous metal layers.

17. The method of claim 16, wherein forming the reflective pattern comprises:

forming a photoresist pattern on the mesa area;

forming a reflective metal layer on the second semiconductor layer through a space opened by the photoresist pattern;

forming a stress relief layer on the reflective metal layer;

forming a conductive barrier layer to cover an upper surface and side surfaces of the stress relief layer and side surfaces of the reflective metal layer; and

removing the photoresist pattern.

18. The method of claim 17, wherein the photoresist pattern comprises an overhang structure, an upper portion of which has a greater width than a lower portion thereof.

19. The method of claim 17, wherein the reflective metal layer and the stress relief layer are formed by anisotropic deposition and the barrier layer is formed by isotropic deposition.

20. The method of claim 16, wherein the mesa area is a stripe type or hole type mesa area.