Stacked Full-Color Micro-LED Structure Without Mass Transfer
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Solution Overview
Problem
The integration of multiple sub-pixels emitting different colors to form a full color pixel in micro-LED displays is challenging due to the differences in manufacturing processes and materials, especially when the micro-LED mesas become smaller, making mass transfer of high-resolution micro-displays nearly impossible.
Innovation Solution
A full color LED structure is achieved by stacking LED units with different colors on the same substrate, where each unit includes a semiconductor layer and a color conversion layer to convert light, allowing for the integration of sub-pixels emitting red, green, and blue colors without the need for mass transfer, using ion-implanted materials for electrical isolation and maintaining a flat top surface for subsequent layer bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple sub-pixel LEDs emitting different colors are integrated to form full color pixels, then color display capability is improved, but manufacturing complexity increases significantly
Solution Approach 1:
The patent combines multiple sub-pixel LEDs (red, green, blue) into a single integrated LED structure sharing common electrodes and semiconductor layers. This merging approach enables full color display capability while reducing manufacturing complexity by processing all sub-pixels simultaneously in one fabrication run, eliminating the need for separate mass transfer operations for each sub-pixel type.
Solution Approach 2:
The invention creates a universal LED structure where a single device can emit multiple colors through different sub-pixels. The common anode and cathode layers serve all sub-pixels, and the MQW structure can be configured to produce different wavelengths, making the device multi-functional for full color display applications.
2Ease of manufacture
If mass transfer method is used to integrate micro-LEDs, then sub-pixel integration is achieved, but manufacturing precision deteriorates for high resolution displays
Solution Approach 1:
The patent performs preliminary actions by forming all sub-pixel structures, electrodes, and semiconductor layers in a single integrated fabrication process before final device completion. This preliminary integration of all components in their correct positions eliminates the need for subsequent mass transfer operations, thereby maintaining high manufacturing precision for high resolution displays.
3Manufacturing precision
If micro-LED mesas are made smaller for higher resolution, then display resolution is improved, but integration difficulty increases
Solution Approach 1:
The patent merges multiple sub-pixel structures into a single integrated unit with shared electrodes and semiconductor layers. This merging is particularly beneficial for small micro-LED mesas where individual processing would be extremely difficult. By combining all sub-pixels in one fabrication process, the invention achieves high display resolution while managing integration complexity effectively.
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
This method enables the formation of full color pixels by individually driving sub-pixels to emit primary colors, achieving a wide range of colors without the drawbacks of mass transfer, thereby improving the manufacturing efficiency and resolution of micro-LED displays.
Implementation Method 1
The color conversion layer is formed on the first LED unit to convert light of the first color to light of a third color different from the first color and the second color
Implementation Method 2
The second doping semiconductor layer of the first LED unit is electrically isolated with the second doping semiconductor layer of the second LED unit by an ion-implanted material formed above the first doping semiconductor layer and the MQW layer
Data Source
AI summary
A LED structure includes a substrate, a first semiconductor layer, a second semiconductor layer, and a color conversion layer. The first semiconductor layer is formed on the substrate, and the first semiconductor layer includes a first LED unit and a second LED unit formed therein. The first LED unit and the second LED unit emit light of a first color. The second semiconductor layer is formed above the first semiconductor layer, and the second semiconductor layer includes a third LED unit formed therein. The third LED unit emits light of a second color different from the first color. The color conversion layer is formed on the first LED unit to convert light of the first color to light of a third color different from the first color and the second color.