High voltage low current surface emitting light emitting diode

• US 9,093,293 B2
• Filed: 07/25/2011
• Issued: 07/28/2015
• Est. Priority Date: 04/06/2009
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Ibbetson, James, Garceran, Julio, Brandes, George, Heikman, Sten
• Primary Examiner(s): Page, Dale E
• Application Number:
  US13/190,094
• Publication Number:
  US 20120043563A1
• Time in Patent Office: 1,464 Days
• Field of Search: 257/79, 257/93, 257/98
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• 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 33/0093 Wafer bonding; Removal of the growth substrate
• 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 chip includes a submount, a reflective layer on the submount, an insulating layer on the reflective layer opposite the submount, and a plurality of sub-LEDs on the insulating layer. Each of the sub-LEDs includes a first face adjacent to the submount and a transparent contact on the first face between the sub-LED and the insulating layer and electrical interconnects between adjacent ones of the sub-LEDs.

Claims

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

a submount;

a reflective layer on the submount;

an insulating layer on the reflective layer opposite the submount;

a plurality of sub-LEDs on the insulating layer;

a first transparent contact between a first of the plurality of sub-LEDs and the insulating layer;

a second transparent contact between the second of the plurality of sub-LEDs and the insulating layer;

electrical interconnects between adjacent ones of the plurality of sub-LEDs;

a first side insulator on a first sidewall of the first of the plurality of sub-LEDs;

a second side insulator on a second sidewall of the first of the plurality of sub-LEDs that is opposite the first sidewall; and

a third side insulator on a first sidewall of a second of the plurality of sub-LEDs,

wherein the first transparent contact extends laterally beyond both the first sidewall and the second sidewall of the first of the plurality of sub-LEDs to provide respective first and second shelves,

wherein the second transparent contact extends laterally beyond both the first sidewall and a second sidewall of the second of the plurality of sub-LEDs to provide respective third and fourth shelves,

wherein a first of the electrical interconnects contacts is coupled between the second transparent contact and a cathode contact of the first of the plurality of sub-LEDs so that the first of the electrical interconnects directly contacts a sidewall of the first side insulator and contacts an upper surface of the third shelf of the second transparent contact within an opening between the first and third side insulators, and

wherein a lower surface of the first side insulator contacts an upper surface of the first transparent contact and a lower surface of the second side insulator contacts an upper surface of the first transparent contact.

2. The LED chip of claim 1, wherein the sub-LEDs are electrically connected in series by the electrical interconnects.

3. The LED chip of claim 1, wherein the first electrical interconnect extends onto and directly contacts a sidewall of the third side insulator.

4. The LED chip of claim 1, wherein the submount is electrically conductive, the LED chip further comprising an electrical via passing through the insulating layer and contacting the reflective layer.

5. The LED chip of claim 4, wherein the sub-LEDs are connected in electrical series, the LED chip further comprising a wire bond pad electrically coupled to a first of the plurality of sub-LEDs in the electrical series, and wherein the via is electrically coupled to a last of the plurality of sub-LEDs in the electrical series.

6. The LED chip of claim 1, wherein the submount is electrically insulating, the LED chip further comprising an electrical via passing through the insulating layer, the reflective layer and the submount.

7. The LED chip of claim 1, wherein the first side insulator contacts an upper surface of the first of the plurality of sub-LEDs.

8. The LED chip of claim 7, wherein the second side insulator contacts the upper surface of the first of the plurality of sub-LEDs.

9. The LED chip of claim 1, wherein the insulating layer is a continuous layer that extends, without interruption, underneath each of the plurality of sub-LEDs and underneath a gap between the first and second transparent contacts.

16. The LED chip of claim 1, wherein each of the plurality of sub-LEDs is flip-chip mounted on the submount.

17. The LED chip of claim 1, wherein the first and second transparent contacts comprise p-type ohmic contacts.

18. The LED chip of claim 17, wherein the first of the plurality of sub-LEDs is a vertical LED having a lowermost p-type layer that directly contacts the first transparent contact.

19. The LED chip of claim 1, wherein a gap between the first sidewall of the first of the plurality of sub-LEDs and the first sidewall of the second of the plurality of sub-LEDs is less than 5 microns.

20. The LED chip of claim 1, wherein a gap between the first sidewall of the first of the plurality of sub-LEDs and the first sidewall of the second of the plurality of sub-LEDs is less than 2 microns.

10. A light emitting diode (LED) chip, comprising:

a submount;

a reflective layer on the submount;

an electrically insulating layer on the reflective layer, opposite the submount;

first and second sub-LEDs at spaced-apart locations on the electrically insulating layer;

a first transparent contact between the first sub-LED and the electrically insulating layer;

a second transparent contact between the second sub-LED and the electrically insulating layer; and

a first side insulator on a first sidewall of the first sub-LED, the first side insulator contacting an upper surface of the first transparent contact and an upper surface of the first sub-LED; and

a second side insulator on a second sidewall of the first sub-LED, the second side insulator contacting an upper surface of the first transparent contact and an upper surface of the first sub-LED;

a third side insulator on a first sidewall of the second sub-LED that faces the first sidewall of the first sub-LED, the second side insulator contacting an upper surface of the second transparent contact;

an electrical interconnect that electrically connects a cathode contact of the first sub-LED to an anode contact of the second sub-LED,

wherein the electrical interconnect directly contacts both a sidewall of the first side insulator and a sidewall of the third side insulator, and

wherein the electrically insulating layer is a continuous layer that extends, without interruption, underneath both the first transparent contact and the second transparent contact and underneath a gap between the first and second transparent contacts.

11. The LED chip of claim 10, wherein the first transparent contact extends beyond both the first sidewall and the second sidewall of the first sub-LED to provide respective first and second shelves.

12. A light emitting diode (LED) chip, comprising:

a submount;

a reflective layer on the submount;

an electrically insulating layer on the reflective layer, opposite the submount;

first and second sub-LEDs at spaced-apart locations on the electrically insulating layer;

a first transparent contact between the first sub-LED and the electrically insulating layer;

a second transparent contact between the second sub-LED and the electrically insulating layer, the second transparent contact separated from the first transparent contact by an insulating spacer;

a first side insulator on a first sidewall of the first sub-LED, the first side insulator contacting an upper surface of the first transparent contact and an upper surface of the first sub-LED;

a second side insulator on a second sidewall of the first sub-LED that is opposite the first sidewall, the second side insulator contacting the upper surface of the first transparent contact and the upper surface of the first sub-LED;

a third side insulator on a sidewall of the second sub-LED that faces the first sidewall of the first sub-LED, the third side insulator contacting an upper surface of the second transparent contact and an upper surface of the second sub-LED,

wherein the electrically insulating layer is a continuous layer that extends, without interruption, underneath the first and second sub-LEDs and underneath the insulating spacer.

13. The LED chip of claim 12, wherein the first transparent contact extends laterally beyond both the first sidewall and the second sidewall of the first sub-LED to provide respective first and second shelves, and wherein the second transparent contact extends laterally beyond the third sidewall of the second sub-LED to provide a third shelf.

14. The LED chip of claim 13, further comprising an electrical interconnect that extends from the upper surface of the first sub-LED to the third shelf of the second transparent contact, the electrical interconnect directly contacting a sidewall of the first side insulator and a sidewall of the third side insulator.

15. The LED chip of claim 14, wherein the electrically insulating layer includes at least one of silicon nitride (SiN), aluminum nitride (AlN), silicon dioxide (SiO₂), titanium dioxide (TiO₂), or aluminum oxide (Al₂O₃).