Micro Device Transfer Using Capillary Liquid Layer

Solution Overview

Problem

Traditional methods for transferring micro devices, such as LEDs, from a transfer wafer to a receiving wafer involve multiple bonding and de-bonding steps, which are complex and costly, and do not efficiently utilize capillary forces for precise placement.

Innovation Solution

A method involving a carrier substrate with an adhesive layer, a transfer head to pick up the micro device, and a receiving substrate with a liquid layer to grip the micro device using capillary forces, allowing for precise placement and reduced adhesive forces, thereby simplifying the transfer process and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional wafer bonding methods are used for transferring micro devices, then the transfer process can be completed, but the process complexity increases and costs increase due to multiple bonding and de-bonding steps

Engineering Contradiction:

Improvetransfer reliabilityVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the intermediate transfer wafer from the traditional bonding process. By using a pick-up tool with a recess that directly receives the micro device from the donor substrate, the method removes the need for transfer wafer bonding and de-bonding steps, thereby simplifying the overall process while maintaining reliable transfer

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces a liquid layer as an intermediary medium between the pick-up tool and the micro device. This liquid layer creates capillary forces that enable reliable gripping and transfer of the micro device without requiring traditional thermal or chemical bonding processes, thus reducing process complexity while ensuring transfer reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If traditional wafer bonding methods are used for transferring micro devices, then the transfer process can be completed, but the manufacturing cost increases due to multiple bonding and de-bonding steps

Engineering Contradiction:

Improvetransfer reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates the intermediate transfer wafer from the traditional bonding process. By using a pick-up tool with a recess that directly receives the micro device from the donor substrate, the method removes the need for transfer wafer bonding and de-bonding steps, thereby simplifying the overall process while maintaining reliable transfer

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces a liquid layer as an intermediary medium between the pick-up tool and the micro device. This liquid layer creates capillary forces that enable reliable gripping and transfer of the micro device without requiring traditional thermal or chemical bonding processes, thus reducing process complexity while ensuring transfer reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If traditional bonding methods are used, then micro devices can be transferred, but precise placement is not efficiently achieved

Engineering Contradiction:

Improveplacement precisionVSAvoidtransfer efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The invention replaces traditional mechanical bonding systems with a capillary force-based system. The liquid layer in the recess of the pick-up tool generates capillary forces that enable precise positioning and secure gripping of the micro device through surface tension effects, achieving both high placement precision and transfer efficiency without complex mechanical bonding mechanisms

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method enables efficient and cost-effective transfer of micro devices by leveraging capillary forces for precise placement, reducing the complexity and cost associated with traditional bonding and de-bonding steps, and ensuring reliable attachment to the receiving substrate.

Implementation Method 1

placing the micro device over the receiving substrate so that the micro device is in contact with the liquid layer and is gripped by a capillary force

Methodology Applied

Scientific EffectCapillary force: Capillary Action

Data Source

PatentUS10643880B2Method for transferring micro device

Publication Date: 2020.05.05 MIKRO MESA TECH

AI summary

A method for transferring a micro device is provided. The method includes: preparing a carrier substrate with the micro device thereon, wherein an adhesive layer is present between and in contact with the carrier substrate and the micro device; picking up the micro-device from the carrier substrate by a transfer head; forming a liquid layer on a receiving substrate; and placing the micro device over the receiving substrate so that the micro device is in contact with the liquid layer and is gripped by a capillary force.