Method and device for self-assembling semiconductor light-emitting diodes

{
  "publication_number": "US10825702B2",
  "country": "US",
  "kind": "B2",
  "title": "Method and device for self-assembling semiconductor light-emitting diodes",
  "abstract": "The present invention relates to a device and method for self-assembling semiconductor light-emitting diodes. Particularly, a method for manufacturing a display device according to the present invention includes: feeding a substrate to an assembly site and putting semiconductor light-emitting diodes having a magnetic material into a fluid chamber; applying a magnetic force to the semiconductor light-emitting diodes so that the semiconductor light-emitting diodes move in one direction within the fluid chamber; and guiding the semiconductor light-emitting diodes to preset positions on the substrate by applying an electric field, so that the semiconductor light-emitting diodes are mounted at the preset positions while in the process of being moved.",
  "claims": [
    "1. A device for self-assembling a plurality of semiconductor light-emitting diodes, the device comprising: a fluid chamber with a space configured to contain a fluid to allow movement of the plurality of semiconductor light-emitting diodes having a magnetic material; a feeder to feed a substrate to an assembly site; a magnet placed at a distance from the fluid chamber and configured to apply a magnetic force to the plurality of semiconductor light-emitting diodes; and a position controller connected to the magnet and configured to control positions of the magnet, wherein the substrate is configured to form an electric field so that the plurality of semiconductor light-emitting diodes will be mounted at preset positions on the substrate while in a process of being moved by changes in the positions of the magnet, and wherein the substrate comprises: a base portion; a plurality of electrodes placed on the substrate, and a dielectric layer that covers the plurality of electrodes when power is applied to the plurality of electrodes, so that the electric field is formed; wherein the substrate is placed in the fluid chamber so that an assembly surface where the plurality of semiconductor light-emitting diodes are assembled faces downwards; wherein the assembly surface of the substrate is dipped in the fluid in the fluid chamber; wherein the magnet is placed to face the opposite side of the assembly surface of the substrate.",
    "2. The device of claim 1, wherein the magnet is configured to rotate in a horizontal, clockwise, or counterclockwise directions to the substrate.",
    "3. The device of claim 1, wherein the substrate further comprises: a plurality of cells sequentially arranged in one direction along barrier walls protruding from the base portion, and wherein the plurality of electrodes are placed on undersides of the plurality of cells.",
    "4. The device of claim 3, wherein the dielectric layer forms a bottom of the plurality of cells, and the dielectric layer is interposed between the plurality of semiconductor light-emitting diodes and the plurality of electrodes so that the plurality of semiconductor light-emitting diodes are not in direct contact with the plurality of the electrodes.",
    "5. The device of claim 3, further comprising a power supply that is electrically connected to the plurality of electrodes so as to generate the electric field by applying power to the plurality of electrodes.",
    "6. The device of claim 1, wherein the fluid chamber includes a light-transmissive bottom plate, and the plurality of semiconductor light-emitting diodes are placed between the light-transmissive bottom plate and the substrate.",
    "7. The device of claim 6, further comprising an image sensor that is placed opposite the light-transmissive bottom plate so as to monitor the inside of the fluid chamber through the light-transmissive bottom plate.",
    "8. The device of claim 1, wherein the magnetic material is provided in a form of particles in a layer, or a layer of the magnetic material.",
    "9. The device of claim 1, wherein a spacing between the plurality of semiconductor light-emitting diodes is controlled by adjusting a strength of the magnetic force."
  ],
  "description_excerpt": "1. Field of the Invention The present invention relates to a method for manufacturing a display device, and more particularly, to a method and device for self-assembling semiconductor light-emitting diodes. 2. Description of the Conventional Art In recent years, in the field of display technology, liquid-crystal displays (LCD), organic light-emitting diode (OLED) displays, microLED displays, etc. have been competing to realize large-area displays. However, LCDs have problems such as slow response times and the low efficiency of light produced by a backlight, and OLEDs have disadvantages such as short lifetimes, low mass-production yields, and low efficiency. On the contrary, semiconductor microLEDs (μLED) with a diameter or cross-sectional area less than 100 microns, when used in displays, may offer very high efficiency because the displays do not need a polarizer to absorb light. However, large-scale displays require several millions of semiconductor light-emitting diodes, which makes it difficult to transfer the devices compared to other technologies.\n\nSome of the technologies currently in development for the transfer process include pick & place, laser lift-off (LLO), and self-assembly. Among these technologies, the self-assembly approach is a method that allows semiconductor light-emitting diodes to find their positions on their own in a fluid, which is most advantageous in realizing large-screen display devices. Recently, U.S. Pat. No.",
  "cpc": [
    "H10W 90/00",
    "B65G 47/92",
    "H01L 21/67144",
    "H01L 25/0753",
    "H01L 2933/0066",
    "H01L 33/0093",
    "H01L 33/0095",
    "H01L 33/62",
    "H10H 20/01",
    "H10H 20/018",
    "H10H 20/0364",
    "H10H 20/857",
    "H10P 72/0446"
  ],
  "ipc": [
    "B65G 47/14",
    "B65G 47/49",
    "B65G 47/92",
    "H01L 21/44",
    "H01L 21/67",
    "H01L 25/075",
    "H01L 29/82",
    "H01L 33/00",
    "H01L 33/62"
  ],
  "assignees": [
    "LG ELECTRONICS INC"
  ],
  "inventors": [
    "SHIM BONGCHU",
    "KIM DOHEE",
    "PARK CHANGSEO",
    "CHO HYUNWOO"
  ],
  "filing_date": "2019-04-18",
  "publication_date": "2020-11-03",
  "grant_date": "2020-11-03",
  "priority_date": "2018-04-19",
  "application_number": "US-201916388394-A",
  "family_id": "68238263",
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  ]
}