LED Wafer Transfer Alignment Using Reference Members

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Solution Overview

Problem

Existing methods of manufacturing display devices with LEDs face challenges in achieving precise alignment accuracy, particularly during the transfer processes, which limits the size and resolution of the display devices and increases production time and cost.

Innovation Solution

A method involving the use of reference members and alignment keys to align wafers with donor substrates, allowing for precise positioning of LEDs, thereby improving alignment accuracy and reducing the complexity of transfer processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional alignment methods are used during transfer processes, then the manufacturing process is simpler, but the alignment accuracy of LEDs deteriorates

Engineering Contradiction:

Improvealignment accuracy of LEDsVSAvoidcomplexity of transfer process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a donor substrate as an intermediary carrier between the wafer and the display panel. The donor substrate receives LEDs during a primary transfer process and then transfers them to the display panel in a secondary transfer process. This intermediary approach enables precise alignment through reference members and alignment keys, solving the alignment accuracy problem while managing process complexity through staged transfers.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent performs preliminary alignment actions by placing reference members and alignment keys on the donor substrate before the actual LED transfer. The alignment keys are positioned in advance to guide the wafer and donor substrate positioning, ensuring high alignment accuracy is achieved before the critical LED placement occurs.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If multiple transfer processes are used to improve alignment accuracy, then the alignment precision improves, but the production time increases

Engineering Contradiction:

Improvealignment accuracy of LEDsVSAvoidproduction time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent combines multiple transfer operations into a coordinated two-stage process. The primary transfer process moves LEDs to the donor substrate, and the secondary transfer process moves them to the display panel. By merging these operations with integrated reference members and alignment keys that work across both stages, the system achieves high alignment accuracy without excessive time loss compared to separate, uncoordinated transfer processes.

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If traditional transfer processes are used, then the process is faster and simpler, but the resolution and alignment accuracy of the display device deteriorates

Engineering Contradiction:

Improvealignment accuracy and resolutionVSAvoidease of transfer process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The donor substrate serves as a mediator that enables high-resolution LED placement. It provides a stable platform with reference members and alignment keys that facilitate precise positioning during both primary and secondary transfers, achieving high manufacturing precision while maintaining reasonable ease of manufacture through the standardized transfer mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the transfer process into distinct primary and secondary stages, each with specific alignment functions. This segmentation allows each stage to be optimized independently - the primary transfer focuses on getting LEDs to the donor substrate, while the secondary transfer focuses on precise placement on the display panel, making the overall complex process more manageable and easier to manufacture.

Inventive Principle:

Principle #1Segmentation

4Manufacturing precision

If alignment keys are transferred with LEDs, then alignment accuracy is maintained, but the process complexity and cost increase

Engineering Contradiction:

Improvealignment accuracyVSAvoidcomplexity of alignment process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The alignment keys serve multiple functions: they are used for aligning the wafer to the donor substrate during primary transfer, and then the same alignment keys on the donor substrate are used for aligning the donor substrate to the display panel during secondary transfer. This multi-functionality maintains alignment accuracy across both stages without requiring separate alignment mechanisms, reducing overall process complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12527115B2Method of manufacturing display device

Publication Date: 2026.01.13 LG DISPLAY CO LTD

AI summary

One aspect of the present disclosure provides a method of manufacturing a display device, including: a process of aligning a first wafer on which a plurality of first LEDs, a plurality of alignment keys, and a reference member are disposed with a donor substrate; a process of transferring the plurality of first LEDs and the reference member on the first wafer to the donor substrate; and a process of aligning a second wafer on which a plurality of second LEDs is disposed with the donor substrate based on the reference member. Therefore, a relative position between the plurality of second LEDs of the second wafer and the plurality of first LEDs of the donor substrate may be precisely aligned based on the reference member that maintains a predetermined interval from the plurality of first LEDs.