Methods of manufacturing light emitting diodes including barrier layers/sublayers

• US 7,611,915 B2
• Filed: 03/20/2007
• Issued: 11/03/2009
• Est. Priority Date: 07/23/2001
• Status: Expired due to Term

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Andrews, Peter S., Williams, Bradley E., Slater, David B. Jr., Edmond, John A., Allen, Scott T.
• Primary Examiner(s): TRAN, MINH LOAN
• Application Number:
  US11/688,605
• Publication Number:
  US 20070161137A1
• Time in Patent Office: 959 Days
• Field of Search: 257/98, 257/99, 257/751, 257/E33.068, 257/E33.069, 438/27, 438/29, 438/653
• US Class Current: 438/27
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/01057 Lanthanum [La]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• 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
• CPC Class Codes: H01L 33/60 Reflective elements
• 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

Semiconductor light emitting devices, such as light emitting diodes, include a substrate, an epitaxial region on the substrate that includes a light emitting region such as a light emitting diode region, and a multilayer conductive stack including a reflector layer, on the epitaxial region. A barrier layer is provided on the reflector layer and extending on a sidewall of the reflector layer. The multilayer conductive stack can also include an ohmic layer between the reflector and the epitaxial region. The barrier layer further extends on a sidewall of the ohmic layer. The barrier layer can also extend onto the epitaxial region outside the multilayer conductive stack. The barrier layer can be fabricated as a series of alternating first and second sublayers.

Claims

1. A method of manufacturing a semiconductor light emitting device that includes a semiconductor region that includes therein a device region and a multilayer conductive stack comprising a reflector layer including a reflector layer sidewall on the semiconductor region, and an ohmic contact layer including an ohmic contact layer sidewall, between the reflector layer and the semiconductor region, the method comprising:

forming a conductive barrier layer directly on the reflector layer that extends directly on the reflector layer sidewall and directly on the ohmic contact layer sidewall.

2. A method according to claim 1 wherein the forming further comprises:

forming a conductive barrier layer directly on the reflector layer and extending directly on the reflector layer sidewall, directly on the ohmic layer sidewall and directly onto the semiconductor region outside the multilayer conductive stack.

3. A method according to claim 1 further comprising:

forming the barrier layer as a plurality of alternating first and second sublayers.

4. A method according to claim 3 wherein the first sublayers include grain boundaries therein that are arranged such that the grain boundaries define an offset brick wall structure of the first sublayers.

5. A method according to claim 3 wherein the forming the barrier layer as a plurality of first and second alternating sublayers further comprises forming the second sublayers to be thinner than the first sublayers.

6. A method according to claim 3 further comprising:

terminating the plurality of alternating first and second sublayers with a first sublayer to define an outer sublayer.

7. A method according to claim 6 wherein the outer sublayer is thicker than the first sublayers.

8. A method according to claim 3 wherein the second sublayers are thinner than the first sublayers.

9. A method according to claim 3 wherein the semiconductor region comprises gallium nitride.

10. A method according to claim 3 wherein the reflector layer comprises silver.

11. A method according to claim 3 wherein the forming the barrier layer as a plurality of first and second alternating sublayers comprises:

forming the first sublayers sufficiently thick to reduce migration of metal from the reflector but sufficiently thin to prevent cracking of the first sublayers and forming the second sublayers sufficiently thick to prevent at least some grain boundaries in the first sublayers from propagating thereacross but sufficiently thin so as not to degrade resistance of the multilayer conductive stack.

12. A method according to claim 1 wherein the semiconductor region comprises an epitaxial region on a substrate.

13. A method according to claim 12 wherein the substrate comprises silicon carbide and the epitaxial region comprises gallium nitride.