Multi-Color LED Stacked Bonding Without Pick-and-Place Transfer
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Solution Overview
Problem
Conventional LED display systems face challenges in achieving high resolution, efficient fabrication, and reliable integration of micro-LEDs with pixel driver circuits, particularly in multi-color displays, due to issues like inefficient pick and place processes, light cross-talk, and thermal mismatch.
Innovation Solution
The proposed solution involves a multi-color LED device structure with multiple light emitting layers stacked horizontally within a pixel area, allowing for efficient fabrication and integration by eliminating the need for extra substrates and simplifying the pixel device structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional pick and place process is used to transfer micro LEDs from separate substrates, then multi-color display can be achieved, but fabrication efficiency is low and process complexity increases
Solution Approach 1:
The patent combines multiple light emitting layers (red, green, blue) into a single integrated LED structure grown on one substrate, eliminating the need for separate substrates and pick-and-place processes. This merging approach maintains multi-color capability while dramatically improving fabrication efficiency and reducing process complexity.
Solution Approach 2:
The patent segments the light emitting function into multiple distinct light emitting layers within a single LED structure, where each layer emits a different color. This segmentation allows full-color display capability to be achieved within one integrated device rather than requiring assembly of separate LEDs.
2Reliability
If entire LED array with original substrate is bonded to control circuitry, then integration is achieved, but light cross-talk occurs and thermal mismatch generates stress
Solution Approach 1:
The patent extracts and removes the original LED substrate after the LED structures are formed, transferring only the LED structures themselves to the control circuitry substrate. This extraction eliminates the source of light cross-talk and thermal mismatch while maintaining reliable integration.
Solution Approach 2:
The patent uses an intermediate transfer substrate to temporarily hold the LED structures during fabrication, allowing precise alignment and transfer to the final control circuitry substrate. This intermediary approach ensures reliable integration while avoiding direct bonding of mismatched materials.
3Measurement precision
If pixel size is reduced to achieve high resolution, then display quality improves, but fabrication precision requirements increase
Solution Approach 1:
The patent merges multiple color functions into a single pixel structure with stacked light emitting layers, allowing high resolution to be achieved without proportionally increasing fabrication precision requirements. The unified growth process on a single substrate provides better dimensional control than assembling separate micro LEDs.
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 approach enhances fabrication efficiency and reliability, reduces light cross-talk and thermal stress, and improves the overall performance and cost ratio of LED display systems, making them suitable for demanding applications like AR, VR, and automotive displays.
Implementation Method 1
bonding the first LED light emitting layer and the second LED light emitting layer together with a first metal bonding layer
Data Source
AI summary
A single pixel multi-color LED device includes two or more LED structures for emitting a range of colors. The two or more LED structures are horizontally formed as sub-pixels to combine light. In some embodiments, two or more light emitting layers are formed on a substrate with integrated circuits and the two or more light emitting layers are bonded together with bonding layers. In some embodiments, the two or more LED structures are formed by utilizing a respective top light emitting layer of the respective LED structure and by removing extra top light emitting layer(s) with the respective LED structure. In some embodiments, the up and down orientation of the P-type region and the N-type region within the first light emitting layer is different from the up and down orientation of the P-type region and the N-type region within the second light emitting layer.