Micro LED Dielectric Stress Recovery Layer for Laser Lift-Off
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Solution Overview
Problem
Micro light-emitting diodes face defects such as cracks and coarsening damage during the laser lift-off process, which can lead to reliability issues due to stress on the epitaxial layer.
Innovation Solution
A dielectric layer is integrated on the first surface of the epitaxial layer, serving as a stress recovery layer to mitigate defects and enhance reliability during the laser lift-off process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the epitaxial layer is separated from the substrate using a laser lift-off process, then the micro light-emitting diode can be transferred to the target substrate, but the epitaxial layer experiences stress that causes cracks and defects
Solution Approach 1:
A stress recovery layer is formed on the epitaxial layer before the laser lift-off process to prevent stress-induced cracks and defects during substrate separation. This preliminary protective measure ensures the epitaxial layer maintains its integrity throughout the transfer process.
Solution Approach 2:
The stress recovery layer acts as an intermediary between the epitaxial layer and the external stress environment during laser lift-off. This intermediate layer absorbs and distributes the stress, preventing direct transmission of damaging forces to the epitaxial layer.
2Ease of operation
If the adhesive film is removed during the laser lift-off process, then the micro light-emitting diode is fully separated from the substrate, but existing cracks and coarsening damage expand further
Solution Approach 1:
The stress recovery layer is prepared in advance to prevent crack propagation during the adhesive film removal process. This pre-established protective structure ensures that even when the adhesive is completely removed, the epitaxial layer remains intact without expanded damage.
3Strength
If the epitaxial layer withstands greater stress during bonding to the base, then the micro light-emitting diode can be securely assembled, but the stress causes cracks and coarsening damage in the epitaxial layer
Solution Approach 1:
The stress recovery layer is formed before the bonding process to provide stress distribution during assembly. This allows the structure to withstand bonding forces while preventing stress concentration that would cause cracks in the epitaxial layer.
Solution Approach 2:
The stress recovery layer serves as a mediator between the bonding interface and the epitaxial layer, distributing mechanical stresses uniformly and preventing localized stress concentration that would lead to cracking during the bonding process.
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
The dielectric layer effectively prevents cracks and further damage to the epitaxial layer, improving the reliability and light-emitting performance of the micro light-emitting diode.
Implementation Method 1
a dielectric layer covering the first surface and at least a portion of a side wall of the epitaxial layer, where a height H1 of the dielectric layer on the side wall of the epitaxial layer is less than a height of the mesa... the dielectric layer can serve as a stress recovery layer, such that during separation of a substrate from the micro light-emitting diode by using a laser lift-off process, the defects of cracks and the like of the epitaxial layer are avoided
Implementation Method 2
during separation of a substrate from the micro light-emitting diode by using a laser lift-off process
Data Source
AI summary
A micro light-emitting diode and a preparation method therefor, a micro light-emitting element and a display. The micro light-emitting diode comprises an epitaxial layer and a dielectric layer, wherein the epitaxial layer comprises a first semiconductor layer, an active layer and a second semiconductor layer which are arranged in sequence, and has a first surface and a second surface which are arranged opposite each other, the first semiconductor layer being located on the side of the epitaxial layer close to the first surface; the epitaxial layer is configured with a mesa, and the mesa is exposed from the first semiconductor layer and faces the second surface; and the dielectric layer covers the first surface and at least part of a side wall of the epitaxial layer, and the height H1 of the dielectric layer on the side wall of the epitaxial layer is less than the height of the mesa.