Multi-Color LED Integration via Alignment Bonding
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Solution Overview
Problem
Conventional methods for fabricating integrated multi-color LED display panels are inefficient and costly due to challenges in aligning and bonding micro LEDs with pixel driver circuitry, leading to issues like light cross-talk, thermal mismatch, and complexity in manufacturing, especially for multi-color panels requiring different color LEDs on various substrate materials.
Innovation Solution
A multi-stage alignment bonding and substrate removal process is used, where LEDs are precisely aligned and bonded to a host wafer with pixel drivers, with each color's LEDs bonded separately, allowing for efficient integration of multiple colors and reducing substrate-related issues by removing the substrate of each LED wafer after bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional metal bonding is used to align and bond the entire LED array with its original substrate to the control circuitry, then the bonding process is simplified, but light cross-talk occurs and thermal mismatch generates stress at the bonding interface causing reliability issues
Solution Approach 1:
The LED array is divided into individual micro LEDs that are transferred separately to the control circuitry substrate, rather than bonding the entire array with its original substrate as a single unit. This segmentation eliminates light cross-talk between adjacent LEDs and reduces thermal mismatch stress by removing the original substrate that causes thermal expansion differences.
Solution Approach 2:
The original substrate of the LED array is removed (taken out) before bonding the micro LEDs to the control circuitry substrate. This extraction eliminates the source of thermal mismatch and light cross-talk, allowing the micro LEDs to be bonded directly to the control circuitry without the interfering original substrate.
2Device complexity
If the entire LED array with its original substrate is bonded to the control circuitry, then the fabrication process is simpler, but light cross-talk occurs between adjacent LEDs
Solution Approach 1:
The LED array is segmented into individual micro LEDs that are transferred and bonded separately to the control circuitry substrate. This segmentation physically isolates each LED, preventing light cross-talk between adjacent LEDs while maintaining a relatively simple fabrication process through wafer-level processing.
Solution Approach 2:
The original substrate is extracted (removed) from the LED array before bonding to the control circuitry. This removal eliminates the source of light cross-talk by allowing each micro LED to be independently positioned and bonded without the constraint of the original substrate structure.
3Manufacturing precision
If conventional methods are used to transfer micro LEDs to an intermediate substrate and then pick and place them onto the control circuitry substrate, then alignment can be achieved, but the fabrication process becomes inefficient and costly
Solution Approach 1:
The alignment and bonding operations are merged into a single wafer-level process where the entire LED wafer is aligned and bonded to the control circuitry wafer simultaneously. This eliminates the need for intermediate substrate transfer and individual pick-and-place operations, dramatically improving fabrication efficiency while maintaining precise alignment through wafer-level registration features.
Solution Approach 2:
Alignment features and bonding structures are prepared in advance on both the LED wafer and control circuitry wafer before the bonding process. This preliminary preparation enables precise alignment during the bonding step without requiring complex real-time alignment mechanisms,从而提高 manufacturing precision and efficiency.
4Adaptability or versatility
If multi-color display panels require different color LEDs grown on different substrate materials, then color diversity is achieved, but the traditional manufacturing process becomes even more complicated and inefficient
Solution Approach 1:
Different color LEDs are fabricated on separate wafer substrates according to their specific material requirements, then segmented and transferred to the control circuitry substrate in a systematic manner. This segmentation allows each color to be optimized for its specific substrate while maintaining overall process efficiency through wafer-level processing.
Solution Approach 2:
A universal wafer-level bonding process is developed that can handle multiple substrate materials and colors. This universal process uses standardized alignment and bonding techniques that work across different substrate types, reducing the complexity that would otherwise arise from handling multiple color LEDs on different substrates.
Data Source
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Figure 2A
AI summary
Embodiments include a manufacturing method of making a semiconductor device via multiple stages of alignment bonding and substrate removal. One example is an integrated full-color LED display panel, in which multiple wafers with different arrays of LEDs are integrated onto a host wafer with driver circuitry. The driver circuitry typically is an array of pixel drivers that drive individual LEDs on the display panel.