μLED Chip Insulating Protrusion for High-Yield Transfer
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Solution Overview
Problem
The yield of transferring micro light-emitting diodes (μLEDs) from a substrate to a display substrate is low due to excessive adhesion between the μLEDs and adhesive materials during the transfer process.
Innovation Solution
The insulating layer of the μLED chip features a protruding portion that reduces contact area with the adhesive material, allowing for easier detachment and improved yield during transfer by inserting into the adhesive, thereby minimizing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the μLEDs are transferred from substrate to display substrate using adhesive materials, then the μLEDs can be mounted on the display substrate, but excessive adhesion between the μLEDs and adhesive materials causes low transfer yield
Solution Approach 1:
The insulating layer is divided into different height regions: a first region at the same level as the semiconductor layer and a second region protruding above the semiconductor layer. This segmentation creates zones with different adhesion characteristics, allowing the protruding second region to minimize excessive adhesion while the first region maintains necessary structural support.
Solution Approach 2:
Different regions of the insulating layer are given different heights and adhesion properties. The protruding second region has reduced adhesion to prevent excessive bonding, while the first region maintains standard adhesion. This local differentiation of properties solves the contradiction between needing adhesion for mounting and avoiding excessive adhesion for easy transfer.
2Device complexity
If the insulating layer completely covers the semiconductor layer at the same level, then the structure is simple, but the adhesion with adhesive material is too strong causing detachment issues during transfer
Solution Approach 1:
The insulating layer is segmented vertically into two distinct regions: a first region co-level with the semiconductor layer and a second region protruding above it. This segmentation creates differential adhesion zones that prevent complete bonding, ensuring reliable detachment during transfer while maintaining structural integrity.
Solution Approach 2:
The insulating layer extends in the vertical dimension by creating a protruding second region above the semiconductor layer level. This dimensional extension creates a geometry that reduces contact area and adhesion strength, solving the detachment reliability issue without significantly increasing horizontal structural complexity.
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 protruding portion of the insulating layer enhances the yield of μLED transfer by reducing adhesion, preventing detachment issues and ensuring smooth transfer to subsequent carriers.
Implementation Method 1
the insulating layer is able to deflect light emitting from the semiconductor layer
Data Source
AI summary
A light-emitting diode chip includes a semiconductor layer, an insulating layer, a first and a second electrode. The semiconductor layer has a top side, a bottom side opposite to the top side and a sidewall connecting the top side and the bottom side, and a concave-convex structure is at the top side of the semiconductor layer. The insulating layer covers the sidewall and the bottom side of the semiconductor layer, and has a protruding portion extending and protruding above the concave-convex structure along a direction parallel to the sidewall. A vertical distance between a highest point of the concave-convex structure and that of the protruding portion is from 0.5 μm to four times the thickness of the semiconductor layer. The first and the second electrode are on the bottom side of the semiconductor layer and penetrate through the insulating layer. The second electrode is adjacent to the first electrode.