Vertical LED with current guiding structure

• US 8,003,994 B2
• Filed: 06/25/2010
• Issued: 08/23/2011
• Est. Priority Date: 06/12/2007
• Status: Expired due to Fees

• Current Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Original Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Inventors: Liu, Wen-Huang, Chu, Chen-Fu, CHU, JIUNN-YI, Cheng, Chao-Chen, Cheng, Hao-Chun, Fan, Feng-Hsu, Chang, Yuan-Hsiao
• Primary Examiner(s): Soward, Ida M
• Application Number:
  US12/823,866
• Publication Number:
  US 20100258834A1
• Time in Patent Office: 424 Days
• Field of Search: 257/13, 257/79, 257/94, 257/E33.001, 257/E33.002, 257/E33.012, 257/E33.062
• US Class Current: 257/79
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/4903 Connectors having different sizes, e.g. different diameters
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• 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 33/38 with a particular shape
• CPC Class Codes: H01L 33/385 the electrode extending at least partially onto a side surface of the semiconductor body
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

Techniques for controlling current flow in semiconductor devices, such as LEDs are provided. For some embodiments, a current guiding structure may be provided including adjacent high and low contact areas. For some embodiments, a second current path (in addition to a current path between an n-contact pad and a metal alloy substrate) may be provided. For some embodiments, both a current guiding structure and second current path may be provided.

Claims

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

a metal substrate;

an LED stack for emitting light disposed above the metal substrate, wherein the LED stack comprises a p-type semiconductor layer and an n-type semiconductor layer;

an n-electrode disposed above the n-type semiconductor layer;

a protective device disposed above the n-type semiconductor; and

an electrically conductive material coupled between the metal substrate and the protective device.

2. The LED according to claim 1, wherein the protective device comprises at least one of ZnO, ZnS, TiO₂, NiO, SrTiO₃, SiO₂, Cr₂O₃, or polymethyl-methylacrylate (PMMA).

3. The LED according to claim 1, wherein the thickness of the protective device is in a range from 1 nm to 10 μ

m.

4. The LED according to claim 1, further comprising a p-electrode interposed between the metal substrate and the LED stack, wherein the p-electrode comprises first and second contacts, the first contact having a higher resistance than the second contact.

5. The LED according to claim 4, wherein the p-electrode comprises an omni-directional reflective (ODR) system.

6. The LED according to claim 1, wherein the conductive material comprises multiple metal layers.

7. The LED according to claim 1, wherein the conductive material comprises at least one of Ni, Ag, Au, Al, Mo, Pt, W, W—

Si, Ta, Ti, Hf, Ge, Mg, Zn, W/Au, Ta/Au, Pt/Au, Ti/Au, Ti/Al, Ti/Pt/Au, Ti/Ni/Au, Ta/Pt/Au, W—

Si/Au, Cr/Au, Cr/Al, Ni/Au, Ni/Al, Cr/Ni/Au, Cr/W/Au, Cr/W—

Si/Au, Cr/Pt/Au, AuGe, AuZn, indium tin oxide (ITO), indium zinc oxide (IZO), or Ni/Cu.

8. The LED according to claim 1, further comprising an electrically insulative material between the LED stack and the conductive material.

9. The LED according to claim 8, wherein the insulative material comprises at least one of SiO₂, Si₃N₄, TiO₂, Al₂O₃, HfO₂, Ta₂O₅, spin-on glass (SOG), MgO, polymer, polyimide, photoresistance, parylene, SU-8, or thermoplastic.

10. The LED of claim 1, further comprising a bonding layer interposed between the conductive material and the protective device.

11. The LED of claim 10, wherein the conductive material is a wire coupled between the metal substrate and the bonding layer.

12. The LED according to claim 10, wherein the bonding layer comprises multiple metal layers.

13. The LED according to claim 10, wherein the bonding layer comprises at least one of Ti/Au, Ti/Al, Ti/Pt/Au, Cr/Au, Cr/Al, Al, Au, Ni/Au, Ni/Al, or Cr/Ni/Au.

14. The LED according to claim 10, wherein the thickness of the bonding layer is in a range from 0.5 to 10 μ

m.

15. The LED according to claim 1, wherein a surface of the n-type semiconductor layer is patterned or roughened in an effort to increase light extraction from the LED.

16. A light-emitting diode (LED), comprising:

a metal substrate;

a p-electrode disposed above the metal substrate and having first and second contacts, wherein the first contact has a higher electrical resistance than the second contact;

an LED stack for emitting light disposed above the p-electrode, wherein the LED stack comprises a p-type semiconductor layer coupled to the p-electrode and an n-type semiconductor layer; and

an n-electrode disposed above the n-type semiconductor layer.

17. The LED according to claim 16, wherein the first contact comprises a barrier metal layer.

18. The LED according to claim 16, wherein the first contact comprises multiple metal layers.

19. The LED according to claim 16, wherein the first contact comprises at least one of Pt, tantalum (Ta), tungsten (W), W—

Si, Ni, Cr/Ni/Au, W/Au, Ta/Au, Ni/Au, Ti/Ni/Au, W—

Si/Au, Cr/W/Au, Cr/W—

Si/Au, Pt/Au, Cr/Pt/Au, or Ta/Pt/Au.

20. The LED according to claim 16, wherein the second contact comprises a reflective layer.

21. The LED according to claim 16, wherein the second contact comprises at least one of silver (Ag), gold (Au), aluminum (Al), Ag—

Al, Mg/Ag, Mg/Ag/Ni/, Mg/Ag/Ni/Au, AgNi, Ni/Ag/Ni/Au, Ag/Ni/Au, Ag/Ti/Ni/Au, Ti/Al, Ni/Al, AuBe, AuGe, AuPd, AuPt, AuZn, indium tin oxide (ITO), indium zinc oxide (IZO), or an alloy containing at least one of Ag, Au, Al, nickel (Ni), magnesium (Mg), chromium (Cr), platinum (Pt), palladium (Pd), rhodium (Rh), or copper (Cu).

22. The LED according to claim 16, wherein the p-electrode comprises an omni-directional reflective (ODR) system.

23. The LED according to claim 16, wherein an area of the second contact is larger than an area of the first contact resistance.

24. The LED according to claim 16, wherein the first contact is disposed in a voided space of the second contact.

25. The LED according to claim 16, wherein the resistance of the first contact is at least double the resistance of the second contact.

26. The LED according to claim 16, wherein the thickness of the metal substrate is in a range from 10 to 400 μ

m.

27. The LED according to claim 16, wherein the LED is a vertical light-emitting diode (VLED).