Mini LED Substrate Thinning via Laser Roughening
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Solution Overview
Problem
Current methods for thinning mini LED device substrates to below 80 µm result in warpage and breakage due to stress between the substrate and epitaxial structure, leading to low production yield and light blocking issues in display applications.
Innovation Solution
A light-emitting device with a substrate thickness less than 80 µm and a roughened surface structure achieved through laser processing, which reduces warpage and enhances light exiting efficiency by forming a roughened structure on the second surface, allowing for thinner substrates without chipping or cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If chemical mechanical polishing (CMP) is used to thin the substrate to below 80 μm, then the substrate thickness is reduced, but the LED wafer warps significantly causing edges to chip and crack
Solution Approach 1:
The patent replaces the mechanical chemical mechanical polishing (CMP) system with a laser-based processing system. The laser processing method uses optical energy to ablate and thin the substrate without the mechanical contact and stress that causes warpage and edge damage in traditional CMP processes.
Solution Approach 2:
The patent changes the physical parameters of the substrate surface by creating a roughened structure with controlled surface roughness (Ra value between 0.1-1.0 μm) through laser processing. This surface modification allows for thinner substrates while maintaining structural integrity and preventing the warpage issues associated with conventional thinning methods.
2Illumination intensity
If the substrate is thinned to reduce light blocking at seams, then the displaying effect is enhanced, but the substrate becomes more prone to breakage
Solution Approach 1:
The patent modifies the surface parameters of the substrate by creating a roughened structure with specific surface roughness values (Ra 0.1-1.0 μm). This surface modification enhances light extraction efficiency while the controlled thinning process maintains adequate substrate strength to prevent breakage during handling and operation.
Solution Approach 2:
The patent applies partial thinning rather than complete thinning of the substrate. By removing only the necessary amount of material to achieve the desired light extraction while maintaining a minimum thickness for structural integrity, the substrate remains strong enough to prevent breakage while still reducing light blocking at seams.
3Manufacturing precision
If the substrate is thinned to improve resolution and visual effect, then display performance is enhanced, but production yield rate decreases due to breakage
Solution Approach 1:
The patent replaces mechanical thinning processes with laser-based processing, which provides more precise control over substrate thickness and reduces mechanical stress that causes breakage. This substitution enables achieving the required thinning for high resolution displays while maintaining higher production yield rates by minimizing defect generation.
Solution Approach 2:
The patent implements precise control of substrate thickness and surface roughness parameters through laser processing. By optimizing these parameters, the process achieves the necessary thinning for improved display resolution while maintaining substrate integrity, thereby enhancing production yield rate compared to conventional methods.
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 method effectively reduces substrate thickness while preventing warpage and breakage, improving production yield and light exiting efficiency, thus enhancing the visual effect and resolution of mini LED displays.
Implementation Method 1
laser processing the substrate for thinning the substrate and forming a roughened structure on the second surface of the substrate
Data Source
AI summary
A light-emitting device includes a substrate that has a first surface and a second surface opposite to the first surface. The substrate has a thickness that is smaller than 80 µm, and the second surface has a roughened structure thereon with a surface roughness ranging from 0.5 µm to 1 µm. The light-emitting device further includes a chip unit that is disposed on the first surface of the substrate. A method for manufacturing the light-emitting device includes the steps of: providing an LED wafer that has a substrate and at least one chip unit, the substrate having a first surface and a second surface that is opposite to the first surface, the at least one chip unit being disposed on the first surface of the substrate; and laser processing the substrate for thinning the substrate and forming a roughened structure on the second surface of the substrate.