Micro-LED Self-Assembly With Covalent Bonding for Transfer Accuracy

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Solution Overview

Problem

Current manufacturing processes for large-screen displays using micro-size semiconductor light-emitting diodes face challenges in achieving high reliability, improving transfer accuracy, and preventing semiconductor light-emitting diodes from being separated from the substrate during self-assembly.

Innovation Solution

A display device with semiconductor light-emitting diodes, wiring electrodes, and a covalent bond layer that forms bonds with the diodes, utilizing magnetic and electric fields for self-assembly, and heat treatment to secure the diodes on a substrate, allowing for precise positioning and transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If self-assembly method is used to transfer semiconductor light-emitting diodes, then productivity is improved by enabling large-scale simultaneous assembly, but manufacturing precision deteriorates due to difficulty in controlling transfer accuracy

Engineering Contradiction:
Improveassembly throughputVSAvoidtransfer accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent introduces a fluid medium as an intermediary between the semiconductor light-emitting diodes and the substrate. The fluid allows the diodes to be transported and positioned through controlled flow dynamics, enabling both high-throughput assembly and precise positioning. The fluid acts as a carrier that can simultaneously handle multiple diodes while allowing individual control of their placement locations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent utilizes changes in fluid flow parameters (velocity, pressure, direction) to control the positioning and assembly of semiconductor light-emitting diodes. By dynamically adjusting fluid flow parameters, the system achieves both high productivity through continuous flow and high precision through controlled deposition zones where diodes are assembled onto the substrate.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If conventional transfer methods are used, then manufacturing precision is maintained, but productivity deteriorates due to difficulty in transferring millions of diodes for large-scale displays

Engineering Contradiction:
Improvetransfer accuracyVSAvoidassembly throughput
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent employs self-assembly mechanisms where semiconductor light-emitting diodes automatically position themselves on the substrate through their interaction with the fluid medium and substrate surface properties. This self-service approach eliminates the need for complex robotic manipulation of each individual diode, thereby dramatically increasing productivity while maintaining positioning accuracy through controlled self-organization.

Inventive Principle:
Principle #25Self-service

3Productivity

If semiconductor light-emitting diodes are self-assembled onto substrate, then productivity is improved, but reliability deteriorates due to risk of diode separation from substrate

Engineering Contradiction:
Improveassembly throughputVSAvoidbonding reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary surface treatment to both the semiconductor light-emitting diodes and the substrate before assembly. This preliminary action creates complementary surface properties that enhance bonding reliability. The surface treatment prepares the interfaces for strong adhesion, ensuring that diodes remain securely attached to the substrate even after high-throughput self-assembly processes.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the efficient and cost-effective assembly of large numbers of semiconductor light-emitting diodes on a small wafer for large-area displays, ensuring high transfer accuracy and preventing diode separation, thus facilitating the production of high-quality, low-cost large-area display devices.

Implementation Method 1

a covalent bond layer disposed between the dielectric layer and the semiconductor light emitting diodes and forming a covalent bond with the dielectric layer and each of the semiconductor light emitting diodes

Methodology Applied
Scientific EffectCovalent bonding: Chemical Bonding

Implementation Method 2

a plurality of pair electrodes disposed on a substrate and having a first electrode and a second electrode that generate an electric field when a current is supplied

Methodology Applied
Scientific EffectElectric field: Electric Field

Data Source

PatentEP3989284B1Display device and self-assembly method for semiconductor light-emitting device
Publication Date: 2024.09.11 LG ELECTRONICS INC
  • EP3989284B1 patent drawingFigure 1
  • EP3989284B1 patent drawingFigure 2~3
  • EP3989284B1 patent drawingFigure 4~5A

AI summary

A display device can include a plurality of semiconductor light emitting diodes; first and second wiring electrodes respectively extending from the plurality of semiconductor light emitting diodes to supply an electrical signal to the plurality of semiconductor light emitting diodes; a plurality of pair electrodes disposed on a substrate and having a first electrode and a second electrode that generate an electric field when a current is supplied thereto; a dielectric layer disposed to cover the plurality of pair electrodes; and a covalent bond layer disposed between the dielectric layer and the plurality of semiconductor light emitting diodes, and forming a covalent bond with the dielectric layer and each of the plurality of semiconductor light emitting diodes, wherein the first wiring electrode and the second wiring electrode are located at opposite sides of the plurality of pair electrodes based on the plurality of semiconductor light emitting diodes.