Laser Release Layer Transfer for Uniform LED Element Lift-Off

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Solution Overview

Problem

The existing methods for transferring light-emitting elements from a first substrate to a second substrate in light-emitting device manufacturing lack reliability, often resulting in incomplete or inaccurate transfers due to non-uniform laser intensity distributions and potential damage to the semiconductor layered body.

Innovation Solution

A method involving a release layer that is removed by laser irradiation through the first substrate, with a controlled intensity distribution where the maximum intensity is 150% or less of the minimum intensity required for removal, ensuring uniform sublimation and reducing damage to the light-emitting element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional laser irradiation is used for removing the release layer, then the release layer can be removed, but the intensity distribution is non-uniform causing incomplete or inaccurate transfer

Engineering Contradiction:

Improvetransfer reliabilityVSAvoidtransfer accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent controls the intensity distribution parameter of laser light by adjusting optical system parameters (lens focal length, laser power, irradiation position) to ensure uniform intensity across the release layer, transforming the non-uniform intensity problem into a controlled uniform intensity process

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent establishes feedback control by measuring the intensity distribution and adjusting laser parameters to maintain maximum intensity at 150% or less of minimum intensity, ensuring complete and uniform release layer removal without damaging the light-emitting element

Inventive Principle:

Principle #23Feedback

2Productivity

If high intensity laser light is used to remove the release layer, then removal efficiency increases, but the light-emitting element may be damaged

Engineering Contradiction:

Improverelease layer removal efficiencyVSAvoiddamage to semiconductor layered body

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent optimizes laser parameters (intensity distribution, wavelength, pulse duration) to achieve the threshold effect where the release layer is removed at exactly 150% of minimum intensity while keeping the light-emitting element below damage threshold, balancing removal efficiency with element safety

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different intensity levels to different regions: higher intensity (up to 150% of minimum) on the release layer for efficient removal, and controlled intensity on the light-emitting element to prevent damage, creating localized quality differences in laser interaction

Inventive Principle:

Principle #3Local quality

3Speed

If non-uniform intensity distribution is used, then processing speed may increase, but the transfer completeness deteriorates

Engineering Contradiction:

Improveprocessing speedVSAvoidtransfer completeness

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent transforms the intensity distribution parameter from non-uniform to uniform by controlling optical parameters, ensuring that all regions of the release layer receive sufficient intensity (minimum intensity or higher) for complete removal while maintaining processing speed through optimized laser power and scan speed

Inventive Principle:

Principle #35Parameter changes

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

This approach enhances the reliability of light-emitting element transfer by ensuring uniform laser ablation of the release layer, improving the accuracy and efficiency of the transfer process while minimizing damage to the semiconductor layered body.

Implementation Method 1

removing the release layer by irradiating the release layer with laser light from a side of the second surface, opposite the first surface, through the first substrate

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

ensuring uniform sublimation and reducing damage to the light-emitting element

Methodology Applied

Scientific EffectSublimation: Sublimation

Data Source

PatentUS20240405155A1Method for transferring light-emitting element and method for manufacturing light-emitting device

Publication Date: 2024.12.05 NICHIA CORP

AI summary

A method for transferring a light-emitting element from a first substrate to a second substrate includes: providing the light-emitting element fixed to a first surface of the first substrate via a release layer; and removing the release layer by irradiating the release layer with laser light from a side of the second surface, opposite the first surface, through the first substrate. An intensity distribution of the laser light on the first surface is, in the entire release layer, equal to or higher than a minimum intensity at which the release layer can be removed, and a maximum intensity of the intensity distribution is 150% or less of the minimum intensity.