High efficiency white light emitting diode

• US 6,614,172 B2
• Filed: 11/30/2000
• Issued: 09/02/2003
• Est. Priority Date: 02/02/2000
• Status: Active Grant

• Current Assignee: Display Vectors LLC (Jeffrey M. Gross)
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chen, Chiu-Ling, Chiu, Chien-Chia, Shih, Kwang-Kuo
• Primary Examiner(s): Bruce, David V.
• Assistant Examiner(s): KEANEY, ELIZABETH MARIE
• Application Number:
  US09/726,461
• Publication Number:
  US 20010010449A1
• Time in Patent Office: 1,006 Days
• Field of Search: 313/501, 313/512, 313/498, 313/110, 313/112, 257/98, 257/99, 257/100, 257/81
• US Class Current: 313/501
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/06102 the bonding areas being at different heights
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 2224/1703 Bump connectors having different sizes, e.g. different diameters, heights or widths
• 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 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/06 of a plurality of bonding areas
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/10158 at the passive surface
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• 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 high efficiency white light emitting diode, having a light emitting diode chip, a transparent substrate, a transparent Ohmic electrode, a reflection layer, a contact diode and covered with submount with a conductive trace. The transparent substrate having a rough surface is disposed on a first surface of the chip. The transparent Ohmic electrode is disposed on a second surface of the chip and coupled with the contact electrode. The submount with the conductive trace used to carry the chip has a high thermal conductivity. The conductive trace is electrically connected to the contact electrode on the chip by soldering material. The surface of the chip is covered with fluorescent paste to absorb a portion of the light generated by the light emitting diode and to emit a complementary light, so that the observer can observe a white light.

Claims

1. A high efficiency white light emitting diode, comprising:

a light emitting diode chip, comprising a first surface and a second surface;

a transparent substrate, disposed on the first surface of the light emitting diode chip and having a roughened surface;

a transparent Ohmic electrode, disposed on the second surface of the light emitting diode chip with an edge portion of the second surface exposed;

a reflection reflection layer, disposed on the transparent Ohmic electrode, so that the transparent Ohmic electrode is located between the light emitting diode and the reflection reflection layer;

a first contact electrode, disposed on the metal reflection layer to electrically connect the transparent Ohmic electrode via the metal reflection layer;

a second contact electrode, disposed on exposed edge portion of the second surface;

a submount, comprising at least two conductive traces corresponding to the first contact electrode and the second contact electrode respectively, the light emitting diode chip being disposed on the submount via a flip chip technique;

a plurality of soldering materials, disposed on one of the first contact electrode and the corresponding conductive traces and one of the second contact electrode and the corresponding conductive traces thereof, to electrically connect the first contact electrode with its corresponding conductive trace and the second contact electrode with its corresponding conductive trace; and

a fluorescent paste, disposed on the transparent substrate to cover the light emitting diode.

2. The white light emitting diode according to claim 1, wherein the light emitting diode chip comprises a blue light emitting diode chip.

3. The white light emitting diode according to claim 1, wherein the fluorescent paste comprising a fluorescent powder to absorb a portion of a light emitted by the light emitting diode chip and to generate a complementary light to result in a white light.

4. The white light emitting diode according to claim 1, wherein the roughened surface of the transparent substrate has a roughness of about 0.1 micron to about 1.0 micron.

5. The white light emitting diode according to claim 1, wherein the roughened surface includes a regular rabbet surface.

6. The white light emitting diode according to claim 1, further comprises an anti-reflection layer disposed on the roughened surface to enhance the output efficiency of the light.

7. The white light emitting diode according to claim 1, wherein the metal reflection layer is selected from a group of metals comprising silver and aluminum.

8. The white light emitting diode according to claim 1, wherein the material of the submount comprises a high thermal conductive material.

9. The white light emitting diode according to claim 1, wherein the material of the submount is selected from a group of materials comprising artificial diamond, aluminum nitride, aluminum oxide, and silicon carbide.

10. The white light emitting diode according to claim 1, wherein the soldering materials are selected from a group comprising tin-gold alloy, tin-lead alloy, tin-silver alloy and indium.

11. The white light emitting diode according to claim 1, further comprising:

a lead frame, comprising a reflector thereon to carry the submount therein; and

two conductive wires, arranged between the conductive traces and the lead frame for electrical connection.

12. The white light emitting diode according to claim 11, wherein the material of the conductive wires is selected from a group comprising gold and aluminum.

13. The white light emitting diode according to claim 1, wherein the submount comprises a first mounting surface and a second mounting surface, and the conductive traces are located on the first mounting surface and extending to the second mounting surface, the portion of the conductive traces extending on the second mounting surface electrically connects to an external device via a surface mounting technique.

14. A white light illuminating device, comprising:

a plurality of white light emitting diodes arranged as an array, wherein each white light emitting diode further comprises;

a light emitting diode, comprising a first and a second surface;

a transparent substrate on the first surface with a roughened surface;

a transparent Ohmic electrode, on the second surface;

a metal reflection layer, on the transparent Ohmic electrode, such that the transparent Ohmic electrode is formed between the transparent substrate and the metal reflection layer;

a first contact electrode, on the metal reflection layer to electric connect the metal reflection layer;

a second contact electrode, disposed on an exposed edge portion of the second surface;

a submount, comprising at least two conductive traces, respectively corresponding to the first and the second contact electrodes, the light emitting diode chip being mounted on the submount by a flip chip technique;

a plurality of soldering,

a plurality of soldering materials, on one of the conductive traces and the second contact electrode, and the other one of the conductive traces and the second contact electrode, so as to electrically connect one of the conductive traces to the second contact electrode and the other to the first contact electrode;

a flourescent paste, located on the transparent substrate to cover the light emitting diode chip.

15. The white light emitting diode according to claim 14, wherein the light emitting diode chip comprises a blue light emitting diode chip.

16. The white light emitting diode according to claim 14, wherein the fluorescent paste comprising a fluorescent powder to absorb a portion of a light emitted by the light emitting diode chip and to generate a complementary light to result in a white light.

17. The white light emitting diode according to claim 14, wherein the roughened surface of the transparent substrate has a roughness of about 0.1 micron to about 1.0 micron.

18. The white light emitting diode according to claim 14, wherein the roughened surface includes a regular rabbet surface.

19. The white light emitting diode according to claim 14, further comprises an anti-reflection layer disposed on the roughened surface to enhance the output efficiency of the light.

20. The white light emitting diode according to claim 14, wherein the metal reflection layer is selected from a group of metals comprising silver and aluminum.

21. The white light emitting diode according to claim 14, wherein the material of the submount comprises a high thermal conductive material.

22. The white light emitting diode according to claim 21, wherein the material of the submount is selected from a group of materials comprising artificial diamond, aluminum nitride, aluminum oxide, and silicon carbide.

23. The white light emitting diode according to claim 14, wherein the soldering materials are selected from a group comprising tin-gold alloy, tin-lead alloy, tin-silver alloy and indium.