Micro-LED Chip Patterned Structure for Low-Energy Laser Lift-Off
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Solution Overview
Problem
The existing manufacturing processes for micro-LED chips using traditional patterned sapphire substrates require high laser energy and have a small process window, leading to low yield and potential damage or breakage during laser lift-off processing.
Innovation Solution
Designing a micro-LED chip with a specific patterned structure on its light-emitting side, characterized by a peak-valley height difference and size ratio that optimizes light extraction efficiency, reduces laser energy requirements, and increases the process window, using a two-dimensional photonic crystal structure and dry etching methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional patterned sapphire substrate is used for micro-LED chip manufacturing, then light extraction efficiency is improved, but laser energy requirement increases and process window decreases
Solution Approach 1:
The patent changes the geometric parameters of the patterned structure, specifically setting the peak-valley height difference to a precise range (0.01≤c/b≤0.3) and controlling the thickness-to-edge ratio (0.01≤b/a≤6). These parameter optimizations enable effective light extraction while reducing the laser energy needed for lift-off processing.
Solution Approach 2:
The patent introduces a two-dimensional photonic crystal structure on the light-emitting side, adding periodic modulation in two dimensions. This dimensional approach enhances light extraction efficiency through photonic bandgap effects while maintaining compatibility with reduced laser energy processing.
2Illumination intensity
If traditional patterned sapphire substrate is used for micro-LED chip manufacturing, then light extraction efficiency is improved, but chip damage or breakage occurs
Solution Approach 1:
By optimizing the peak-valley height difference parameter to a specific range (0.01≤c/b≤0.3), the patent achieves sufficient light extraction efficiency without creating excessive stress concentrations that would lead to chip damage during laser lift-off processing.
Solution Approach 2:
The patent designs the patterned structure with controlled dimensions and aspect ratios that preemptively prevent stress concentration and chip breakage during the laser lift-off process, cushioning against potential damage before it occurs.
3Illumination intensity
If traditional patterned sapphire substrate is used for micro-LED chip manufacturing, then light extraction efficiency is improved, but manufacturing yield decreases
Solution Approach 1:
The patent establishes specific parameter ranges for the patterned structure (peak-valley height difference ratio and thickness-to-edge ratio) that optimize both light extraction efficiency and manufacturing yield, ensuring high-quality chips are produced consistently.
Solution Approach 2:
The patent applies a moderate peak-valley height difference that is sufficient to improve light extraction but not excessive to cause processing defects, achieving the optimal balance for high manufacturing yield.
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
Improves light extraction efficiency, reduces the risk of chip damage, and enhances the yield of the laser lift-off processing by optimizing the micro-LED chip's structure and manufacturing process.
Implementation Method 1
In order to break total reflection to improve light extraction efficiency (also referred to as extraction efficiency) of the micro-LED chip
Implementation Method 2
the patterned structure is a two-dimensional photonic crystal structure
Data Source
AI summary
A micro-LED chip includes an epitaxial structure, which includes first and second doped type semiconductor layers and an active layer disposed between the first and second doped type semiconductor layers; a light-emitting side of the first doped type semiconductor layer facing away from the active layer is provided with a patterned structure; and an elongated edge a of the micro-LED chip, a thickness b of the micro-LED chip, and a peak-valley height difference c of the patterned structure satisfy: 0.01≤b/a≤6, and 0.01≤c/b≤0.3. By designing a structure size and/or a shape of the micro-LED chip combined with designing the peak-valley height difference of the patterned structure to satisfy the condition of 0.01≤c/b≤0.3, power of laser lift-off operation can be reduced and a process window thereof is enlarged, and light extraction efficiency of the micro-LED chip is achieved. And a display device using the micro-LED chip is provided.