Multi-junction LED Eutectic Bonding Vertical Stacking
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Solution Overview
Problem
Conventional LED manufacturing methods, such as MOCVD, result in significant dislocation defects and large pixel sizes due to the need for multiple LEDs and wiring in microdisplays, limiting optical performance and miniaturization.
Innovation Solution
A multi-junction LED using eutectic bonding with a metal bonding layer, where separately grown light emitting structures are stacked, preventing crystal defects and allowing for optimized adhesive strength, light transmittance, and resistance control, enabling vertical stacking and reduced pixel size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If three LEDs are arranged horizontally to form one pixel, then the pixel can display multiple colors, but the pixel size becomes larger than desired
Solution Approach 1:
The patent transitions from horizontal arrangement of three LEDs to vertical stacking of multiple light emitting structures. The first, second, and third light emitting structures are stacked in the vertical direction, with each structure emitting different colors (red, green, blue). This dimensional change from 2D horizontal layout to 3D vertical stacking reduces the pixel footprint while maintaining full-color capability.
Solution Approach 2:
The patent combines multiple light emitting structures (first, second, and third structures emitting red, green, and blue light respectively) into a single integrated vertical stack. These structures are bonded together through metal bonding layers, merging what would traditionally be separate horizontal components into one compact vertical unit, thereby reducing pixel size while preserving color display functionality.
2Ease of manufacture
If conventional MOCVD process is used to form LED, then the manufacturing process is established, but dislocation defects occur leading to low light output
Solution Approach 1:
The patent divides the LED structure into multiple separately grown light emitting structures that are subsequently bonded together. Each structure (first, second, and third light emitting structures) is grown independently with optimized crystal quality, then joined via metal bonding layers. This segmentation allows each layer to be manufactured with fewer defects while maintaining overall manufacturing feasibility.
Solution Approach 2:
The patent introduces metal bonding layers as intermediary elements between the light emitting structures. These bonding layers serve as mediators that join the separately grown structures while preventing defect propagation. The metal bonding layer acts as a buffer that maintains electrical and mechanical connection without transmitting dislocation defects between layers.
3Adaptability or versatility
If multiple LEDs are used in one pixel, then color display is achieved, but the number of components increases
Solution Approach 1:
The patent merges three separate LEDs (red, green, blue) into a single integrated light emitting device with vertical stacking. The first, second, and third light emitting structures are combined into one compact unit, reducing the component count from three separate LEDs to one integrated structure while maintaining full-color display capability.
Solution Approach 2:
The patent resolves component complexity by transitioning from horizontal arrangement to vertical stacking. By organizing multiple light emitting structures in the vertical dimension rather than horizontal layout, the patent reduces the number of wiring connections and simplifies the overall device architecture while maintaining color display functionality.
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 solution prevents crystal defects between light emitting structures, allows for precise control of light emission characteristics, and minimizes pixel size, enhancing optical performance and mounting efficiency.
Implementation Method 1
a metal bonding layer formed between the third light emitting structure and the insulating layer to bond the third light emitting structure to the insulating layer by using eutectic bonding
Data Source
AI summary
Disclosed are multi-junction light emitting diode (LED) formed by using eutectic bonding and method of manufacturing the multi-junction LED. The multi-junction LED is formed by stacking a separately formed light emitting structure on another light emitting structure by using eutectic bonding. Since separately grown light emitting structure is stacked on the light emitting structure using the eutectic metal alloy bonding, it is possible to prevent crystal defects occurring between the light emitting structures when sequentially grown. Further, since the eutectic metal alloy can be formed in various patterns, it is possible to control and optimize adhesive strength, transmittance of the light generated in the upper light emitting structure, and resistance.