Monolithic RGB MicroLED Array With Low-Damage Epitaxial Fabrication
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Solution Overview
Problem
Conventional microLED fabrication methods require stacking and bonding multiple wafers, which can lead to damage to microLED sidewalls during etching, affecting the performance of the LEDs.
Innovation Solution
The method involves epitaxial growth to fabricate monolithic polychromatic microLEDs at a wafer scale, avoiding the need for wafer stacking and minimizing sidewall damage through selective etching techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional microLED fabrication methods using wafer stacking and bonding are used, then multiple colors (RGB) can be achieved, but damage to microLED sidewalls occurs during etching
Solution Approach 1:
The patent segments the fabrication process into separate epitaxial growth stages for different color layers (blue, green, red) within a single wafer structure. Each color is formed in distinct quantum well layers grown sequentially, eliminating the need to stack and bond multiple wafers. This segmentation allows independent optimization of each color layer while maintaining structural integrity throughout the etching process.
Solution Approach 2:
The patent merges multiple color LED fabrication into a single monolithic wafer structure. Instead of separately fabricating red, green, and blue LED wafers and bonding them together, all three color layers are grown in one continuous epitaxial process on a single sapphire substrate, creating an integrated RGB microLED array that avoids sidewall damage from repeated handling and bonding operations.
2Adaptability or versatility
If wafer stacking and bonding is used to create RGB microLEDs, then color diversity is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent combines the fabrication of red, green, and blue LED layers into a single monolithic wafer using sequential epitaxial growth. This merging eliminates the need for multiple separate fabrication lines, wafer bonding equipment, and alignment processes, significantly reducing manufacturing complexity while maintaining full RGB color capability.
Solution Approach 2:
The patent creates a universal fabrication platform where a single epitaxial growth process can produce all three color layers (red, green, blue) with different quantum well compositions. This multi-functional approach allows one wafer to serve as the source for all RGB microLEDs, eliminating the need for separate specialized fabrication processes for each color.
3Reliability
If selective etching is used in monolithic fabrication, then sidewall damage is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies selective etching with locally optimized conditions for different regions of the wafer. By controlling etch parameters such as chemistry, temperature, and power locally, the process achieves high precision in defining microLED patterns while minimizing sidewall damage. Each color layer and region can be etched with tailored parameters to protect sidewalls while maintaining pattern fidelity.
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 enables the formation of high-performance monolithic RGB microLED pixel arrays with improved efficiency and reduced damage, potentially replacing LCDs and OLEDs in high-resolution displays.
Implementation Method 1
fabricate an LED pixel array from a semiconductor wafer template
Data Source
AI summary
A light emitting diode (LED) pixel array and method of fabrication thereof. A semiconductor wafer template includes a successively stacked first n-GaN layer, first MQW layer, p-GaN layer, and dielectric layer. A plurality of apertures is formed through the dielectric layer, extending to the p-GaN layer. A plurality of mesas is formed by forming, within each aperture, a second MQW layer and a second n-GaN layer above each second MQW layer. The second n-GaN layer and second MQW layer of each mesa form a respective mesa LED with the p-GaN layer. The first n-GaN layer and first MQW layer form a lower LED with the p-GaN layer.