Transfer-Bonding Light Emitting Device Arrays for Uniform Color Displays
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Solution Overview
Problem
Conventional methods for manufacturing light emitting diode (LED) displays face challenges in colorizing technology due to differing lattice constants of light emitting layers and low efficiency of color conversion materials, making it difficult to grow multiple colored LED layers on a single substrate and achieve uniform coating.
Innovation Solution
A transfer-bonding method for light emitting devices involves forming light emitting devices with sacrificial patterns on a first substrate, applying a protective layer to selectively cover them, and then bonding the uncovered device layers to a second substrate, allowing the sacrificial patterns to be removed and the device layers to be transferred efficiently, enabling the creation of a light emitting device array with different colored layers connected through conductive bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple light emitting layers with different lattice constants are grown on a single substrate using epitaxial technique, then colorizing capability is improved, but manufacturing difficulty increases due to lattice mismatch
Solution Approach 1:
The patent divides the light emitting device structure into separate layers grown on different substrates. Each substrate can be optimized for its specific light emitting layer without lattice mismatch constraints, allowing multiple colored LEDs to be manufactured independently and then integrated through transfer bonding technology.
Solution Approach 2:
The patent introduces transfer bonding technology as an intermediary process between substrate growth and final device assembly. This intermediary step allows decoupling of the growth process from the final integration, enabling each layer to be grown on its optimal substrate and then transferred to the final array substrate.
2Adaptability or versatility
If color conversion materials are used with light emitting diode chips, then colorizing is achieved, but conversion efficiency and coating uniformity deteriorate
Solution Approach 1:
The patent extracts the color conversion function from separate material coatings and integrates it directly into the light emitting layer structure itself. By growing the light emitting layers with appropriate bandgaps on optimized substrates, the color conversion is achieved through the material composition rather than additional conversion layers, improving efficiency.
3Illumination intensity
If light emitting devices are transferred to circuit substrate for monolithic micro-display, then brightness and display quality are improved, but transfer-bonding speed and efficiency worsen
Solution Approach 1:
The patent merges multiple light emitting devices onto a single circuit substrate through batch transfer bonding. By processing arrays of devices simultaneously rather than individually, the transfer-bonding speed and efficiency are dramatically improved while still achieving the required brightness and display quality through proper device arrangement and optical design.
Data Source
AI summary
A light emitting device array including a circuit substrate and a plurality of device layers is provided. The circuit substrate includes a plurality of bonding pads and a plurality of conductive bumps located over the bonding pads. The device layers are capable of emitting different colored lights electrically connected with the circuit substrate through the conductive bumps and the bonding pads. The device layers capable of emitting different colored lights have different thicknesses and the conductive bumps bonded with the device layers capable of emitting different colored lights have different heights such that top surfaces of the device layers capable of emitting different colored lights are located on a same level of height.