Thin-film LED with P and N contacts electrically isolated from the substrate

• US 9,142,742 B2
• Filed: 08/13/2013
• Issued: 09/22/2015
• Est. Priority Date: 06/10/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Lin, Chao-Kun
• Primary Examiner(s): STARK, JARRETT J
• Application Number:
  US13/965,799
• Publication Number:
  US 20130328093A1
• Time in Patent Office: 770 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 2933/0075 relating to heat extraction or cooling elements
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• 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
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements

Abstract

A thin-film light emitting diode includes an insulating substrate, a reflective metal electrode on the insulating substrate forming a current spreading layer, and an epitaxial structure on the electrode.

Claims

1. A thin-film light emitting diode, comprising:

a substrate;

a metal layer formed on a lower surface of the substrate for mounting on a sub-mount;

a conductive adhesive layer formed on an upper surface of the substrate;

a reflective electrode formed on the conductive adhesive layer, wherein the conductive adhesive layer and the reflective electrode are metal and together form a metallic current spreading layer, and an entire edge of the metallic current spreading layer is recessed from an edge of the substrate so as to form a recessed portion;

an epitaxial structure on the reflective electrode, the epitaxial structure comprising an n-type GaN-based layer, a p-type GaN-based layer and an active region between the n-type GaN-based layer and the p-type GaN-based layer, the p-type GaN-based layer disposed between the active region and the metallic current spreading layer, wherein a part of the epitaxial structure is removed so as to form a mesa and expose an upper surface of the metallic current spreading layer; and

a pad contact formed on the exposed upper surface of the metallic current spreading layer for a bonding wire.

2. The thin-film light emitting diode of claim 1, wherein the metallic current spreading layer has a thickness greater than about 1 um.

3. The thin-film light emitting diode of claim 1, wherein the substrate is transparent for the wavelengths between about 300 nm and 700 nm with a transmittance greater than about 50%.

4. The thin-film light emitting diode of claim 1, wherein the substrate is reflective for the wavelength between about 300 nm and 700 nm with a reflectance greater than about 50%.

5. The thin film light emitting diode of claim 1, wherein the n-type GaN-based layer has a roughened surface with micro-structures, the micro-structures being between about 100 nm and 500 nm in size.

6. The thin-film light emitting diode of claim 1, further comprising a patterned second electrode on the n-type GaN-based layer.

7. The thin-film light emitting diode of claim 6, wherein the patterned second electrode is on a top surface of the mesa.

8. The thin-film light emitting diode of claim 1, wherein the substrate is not an original growth substrate for the epitaxial structure.

9. The thin-film light emitting diode of claim 1, wherein said reflective electrode reflects a light emitted from the active region and conducts a current from the pad contact to the epitaxial structure.

10. The thin-film light emitting diode of claim 1, wherein the reflective electrode is formed on the p-type GaN-based layer with a capping layer.

11. The thin-film light emitting diode of claim 10, wherein the capping layer comprises Au.

12. The thin-film light emitting diode of claim 1, wherein the conductive adhesive layer comprises a material selected from the group consisting of eutectic metal, solder metal and silver epoxy.

13. The thin-film light emitting diode of claim 1, wherein the conductive adhesive layer comprises eutectic metal.

14. The thin-film light emitting diode of claim 1, further comprises an insulating layer formed between the substrate and the conductive adhesive layer, wherein the substrate is a conductive substrate.