Micro-LED Transfer via Holding Material Strain Management
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Solution Overview
Problem
The existing micro-LED manufacturing process faces challenges with crack formation during laser lifting-off due to inhomogeneous strain distribution, primarily caused by rough surfaces and misalignment between substrates, leading to yield loss in micro-LED transfers.
Innovation Solution
A method involving the use of a transparent carrier substrate with trenches filled with a holding material, such as photoresist, glue, or polymer, to hold micro-LEDs during laser lifting-off, which reduces strain and misalignment issues by bonding and separating micro-LEDs onto a receiving substrate, and optionally involves heating and cooling to facilitate separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser lifting-off is performed on micro-LEDs from a carrier substrate, then micro-LEDs can be transferred to a receiving substrate, but cracks form in the micro-LEDs due to inhomogeneous strain distribution
Solution Approach 1:
A holding material is introduced as an intermediary substance between the micro-LEDs and the carrier substrate. This holding material serves as a mediator that maintains the micro-LEDs in a stress-free state during the laser lifting-off process, preventing crack formation while enabling successful transfer to the receiving substrate.
Solution Approach 2:
The holding material is applied to the carrier substrate before the micro-LEDs are transferred. This preliminary action prepares the substrate surface to accommodate and protect the micro-LEDs during the subsequent laser lifting-off process, preventing strain-induced cracks before they occur.
2Productivity
If laser lifting-off is performed on micro-LEDs, then transfer to receiving substrate is achieved, but misalignment between micro-LEDs and micro-bumps occurs
Solution Approach 1:
The holding material acts as a mediator that facilitates precise alignment between micro-LEDs and micro-bumps during the transfer process. It provides a stable interface that allows for accurate positioning while maintaining transfer efficiency.
3Productivity
If laser lifting-off is performed on micro-LEDs, then transfer is achieved, but rough surface of receiving substrate causes strain concentration
Solution Approach 1:
The holding material serves as an intermediary layer that compensates for the rough surface of the receiving substrate. It provides a smooth interface between the micro-LEDs and the substrate, distributing strain uniformly and preventing stress concentration points that would lead to cracks.
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 significantly reduces crack formation during micro-LED transfer, enhancing the yield of micro-LEDs transferred to the receiving substrate by ensuring more homogeneous strain distribution and improved alignment.
Implementation Method 1
Laser 108 is irradiated on the selected micro-LEDs 102 from the side of the carrier substrate 101 to perform a laser lifting-off
Data Source
AI summary
A micro-LED display device and a manufacturing method thereof are disclosed. The method comprises: forming micro-LEDs (202) on a carrier substrate (201), wherein the carrier substrate (201) is transparent for a laser which is used in laser lifting-off; filling trenches between the micro-LEDs (202) on the carrier substrate (201) with a holding material (209); performing a laser lifting-off on selected ones of the micro-LEDs (202) to lift off them from the carrier substrate (201), wherein the selected micro-LEDs (202) are held on the carrier substrate (201) through the holding material (209); bonding the selected micro-LEDs (202) onto a receiving substrate (207) of the micro-LED display device; separating the selected micro-LEDs (202) from the carrier substrate (201) to transfer them to the receiving substrate (207).