Micro-LED Package Transfer Using Tether Layers and Post Electrodes

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Solution Overview

Problem

Current technologies face challenges in efficiently transferring and bonding subminiature LED chips for high-resolution displays like AR and VR, particularly due to issues with precise metal processing leading to electrical shorts and deteriorated electrical characteristics.

Innovation Solution

A method involving the formation of a post structure on a semiconductor light emitting device, with a tether layer that can be selectively etched for easy substrate removal, allowing for efficient transfer and bonding of LED chips onto a panel substrate without electrical shorts, using EC etching and specific doping concentrations to enhance conductivity and prevent shorts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional pick-and-place techniques are used for transferring micro-LEDs, then transfer capability is provided, but transfer efficiency and accuracy deteriorate for subminiature LED chips

Engineering Contradiction:

Improvetransfer efficiencyVSAvoidtransfer accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The invention divides the transfer process into two distinct stages: first transferring the LED chip to an intermediate carrier substrate, then transferring from the carrier substrate to the final display panel. This segmentation allows each transfer step to be optimized independently, achieving both high efficiency and high precision for subminiature chips

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces a carrier substrate as an intermediary element between the LED chip and the display panel. This intermediate carrier enables precise positioning and stable handling during transfer, solving the precision problem while maintaining transfer efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If metal layers are deposited on subminiature LED chips, then electrode functionality is provided, but electrical shorts occur due to contact between metal layers

Engineering Contradiction:

Improveelectrical characteristicsVSAvoidelectrical short

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention extends the electrode structure into the vertical dimension by forming protruding posts that rise from the chip surface. This dimensional change separates metal layers in the vertical direction, preventing horizontal contact and electrical shorts while maintaining electrical connectivity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The protruding posts are formed before final electrode deposition and bonding. This preliminary structuring creates built-in isolation features that prevent electrical shorts during subsequent processing steps, eliminating the need for additional protective measures

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If LED chip size is miniaturized for high-resolution displays, then display resolution is improved, but transfer and transmission become more difficult

Engineering Contradiction:

Improvedisplay resolutionVSAvoidtransfer difficulty

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The carrier substrate serves as a mediator that provides a larger, more manageable platform for handling miniaturized LED chips. This intermediary enables precise positioning and stable transfer of subminiature chips without requiring direct manipulation of the tiny chips themselves

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The transfer process is segmented into two stages with the carrier substrate as an intermediate platform. This allows the miniaturized chips to be handled en masse on the carrier rather than individually, dramatically improving ease of manufacture while maintaining high display resolution

Inventive Principle:

Principle #1Segmentation

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 efficient transfer and transmission of ultra-small LED chips with improved electrical characteristics, eliminating the need for dedicated transfer heads and stamps, and achieving high-resolution full-color displays with uniformity.

Implementation Method 1

a step of selectively partially etching the second semiconductor layer by performing EC (Electrical Chemical) etching to form a tether layer

Methodology Applied

Scientific EffectEC etching (Electrochemical etching): Electrolysis

Implementation Method 2

The first semiconductor layer and the second semiconductor layer are each doped with a first conductivity type dopant, and a doping concentration of the first conductivity type dopant of the second semiconductor layer can be higher than that of the first conductivity type dopant of the first semiconductor layer

Methodology Applied

Scientific EffectDoping: Dopants

Data Source

PatentUS20230361095A1Method for manufacturing semiconductor light-emitting device package, semiconductor light-emitting device package manufactured thereby, and display device comprising same

Publication Date: 2023.11.09 LG ELECTRONICS INC

AI summary

Embodiments relate to a method for manufacturing a semiconductor light emitting device package, a semiconductor light emitting device package manufactured by the method, and a display device including the same. The semiconductor light emitting device package according to the embodiment can include a first semiconductor layer on a growth substrate, a tether layer on the first semiconductor layer, a light emitting structure on the tether layer, a light-transmitting electrode layer on the light-emitting structure, and a post structure on the light-transmitting electrode layer.