Micro-LED module and method for fabricating the same

Patent metadata

Field	Value
Publication number	US-10319706-B2
Application number	US-201715818738-A
Country	US
Kind code	B2
Filing date	Nov 20, 2017
Priority date	Feb 10, 2017
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A method for fabricating a micro-LED module is disclosed. The method includes: preparing a micro-LED including a plurality of electrode pads and a plurality of LED cells; preparing a submount substrate including a plurality of electrodes corresponding to the plurality of electrode pads; and flip-bonding the micro-LED to the submount substrate through a plurality of solders located between the plurality of electrode pads and the plurality of electrodes. The flip-bonding includes heating the plurality of solders by a laser.

First claim

What is claimed is:

1. A method for fabricating a micro-LED module comprising:
preparing a micro-LED comprising a plurality of electrode pads and a plurality of LED cells;
preparing a submount substrate comprising a plurality of electrodes corresponding to the plurality of electrode pads; and
flip-bonding the micro-LED to the submount substrate through a plurality of solders located between the plurality of electrode pads and the plurality of electrodes,
wherein the micro-LED comprises a substrate and an epilayer comprising the LED cells,
wherein the flip-bonding comprises heating the plurality of solders by a plurality of laser beams passing vertically through the micro-LED from one side to the other side of the micro-LED, and the plurality of laser beams comprise laser beams passing through the substrate and the epilayer in which none of the LED cells are present and laser beams passing through the substrate and the epilayer in which the LED cells are present.

2. The method according to claim 1 , wherein the individual electrode pads are formed on the LED cells and the flip-bonding comprises heating the solders located between the individual electrode pads and the submount substrate by the plurality of laser beams sequentially passing through the LED cells and the individual electrode pads.

3. The method according to claim 2 , wherein the individual electrode pads are transmissive to the plurality of laser beams.

4. The method according to claim 2 , wherein the individual electrode pads comprise cavities through which the plurality of laser beams pass.

5. The method according to claim 1 , wherein the micro-LED comprises a common electrode pad formed on the surface of the epilayer around the plurality of LED cells and the flip-bonding comprises heating the solder located between the common electrode pad and the submount substrate by the plurality of laser beams sequentially passing through the epilayer and the common electrode pad.

6. The method according to claim 5 , wherein the common electrode pad is transmissive to the plurality of laser beams.

7. The method according to claim 5 , wherein the common electrode pad comprises a cavity through which the plurality of laser beams pass.

8. The method according to claim 1 , further comprising focusing the laser beams on the corresponding solders by focusing lenses.

9. The method according to claim 1 , wherein the flip-bonding comprises placing a plurality of laser beam irradiation units in an arrangement corresponding to an arrangement of the plurality of solders at one side of the micro-LED before heating the plurality of solders by the plurality of laser beams passing vertically through the micro-LED from one side to the other side of the micro-LED.

10. The method according to claim 1 , wherein a plurality of laser beam irradiation units are placed in an arrangement corresponding to an arrangement of the plurality of solders at one side of the micro-LED before heating the plurality of solders by the plurality of laser beams passing vertically through the micro-LED from one side to the other side of the micro-LED and each of the plurality of laser beam irradiation units comprises an optical guide connected to a laser source, a collimator for making laser beams entering through the optical guide parallel to each other, a beam controller for controlling the cross-sectional size of the parallel laser beams, and a focusing lens for focusing the parallel laser beams whose cross-sectional size is controlled on the corresponding solders.

11. The method according to claim 1 , wherein the flip-bonding comprises matching the plurality of solders to the plurality of laser beams in a 1:1 ratio such that the plurality of solders are heated by the plurality of laser beams.

12. The method according to claim 1 , wherein the flip-bonding comprises matching a plurality of laser beam irradiation units to the plurality of solders in a 1:1 ratio such that the plurality of solders are heated by laser beams irradiated from the plurality of laser beam irradiation units.

13. The method according to claim 1 , wherein the flip-bonding comprises matching a plurality of laser beam irradiation units to the plurality of solders in a 1:n (where n is a natural number equal to or greater than 2) ratio such that two or more of the solders are heated by laser beams irradiated from each of the laser beam irradiation units moving in a linear or zigzag pattern.

14. The method according to claim 1 , wherein the flip-bonding comprises matching two or more laser beam irradiation units to two or more solder groups such that each of the laser beam irradiation units heats the solders in the corresponding solder group.

15. A micro-LED module comprising:
a micro-LED comprising a substrate, an epilayer comprising a plurality of LED cells, second conductive individual electrode pads disposed on the plurality of LED cells, and a first conductive common electrode disposed around the plurality of LED cells;
a submount substrate comprising a plurality of electrodes corresponding to the individual electrode pads and the common electrode pad; and
solders located between the electrodes and the individual and common electrode pads,
wherein the solders are heated by a plurality of laser beams and are then hardened so that the electrodes are connected to the individual electrode pads and the common electrode pad,
wherein the plurality of laser beams comprise laser beams passing through the substrate and the epilayer in which none of the LED cells are present and laser beams passing through the substrate and the epilayer in which the LED cells are present.

16. The micro-LED module according to claim 15 , wherein the substrate, the epilayer, the individual electrode pads, and the common electrode pad are transmissive to the laser beams such that the solders are heated by the laser beams passing through the micro-LED from one side to the other side of the micro-LED.

17. The micro-LED module according to claim 15 , wherein the individual electrode pads are made of a laser beam-transmitting material.

18. The micro-LED module according to claim 15 , wherein the individual electrode pads or the common electrode pad comprises cavities through which the laser beams pass.

Assignees

• Lumens Co Ltd

Inventors

• Yoo Taekyung
• Kim Daewon
• Yoon Seongbok
• Won Yelim
• Moon Myungji
• Chang Hanbeet
• Kim Yongpil
• Park Jaesoon

Classifications

• H10W90/722

  between stacked chips · CPC title

• H10W72/07236

  Soldering or alloying · CPC title

• H10W72/07235

  Applying EM radiation, e.g. induction heating or using a laser · CPC title

• H10W72/01938

  in gaseous form, e.g. by CVD or PVD · CPC title

• H10W72/01271

  Cleaning, e.g. oxide removal or de-smearing · CPC title