Micro-LED Stacked Bonding Structure for Multi-Color Display Integration
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Solution Overview
Problem
Conventional LED display fabrication processes are inefficient, costly, and unreliable, particularly for multi-color displays, due to challenges in integrating thousands of micro LEDs with pixel driver circuits and thermal mismatch between substrates, leading to issues like light cross-talk and reliability problems.
Innovation Solution
A multi-color LED device structure with multiple light emitting layers stacked horizontally within a pixel area, allowing for direct bonding to a substrate without retaining extra substrates, and flexible electrode connections, reducing complexity and improving fabrication efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional pick and place method is used to transfer micro LEDs to control circuitry substrate, then individual LED placement is possible, but the fabrication process becomes inefficient, costly and unreliable
Solution Approach 1:
The patent merges multiple micro LEDs onto a single intermediate substrate to form LED arrays, eliminating the need for individual pick and place operations. This consolidation approach improves fabrication efficiency and reliability while reducing costs associated with handling and placing thousands of individual micro LEDs.
Solution Approach 2:
The fabrication process is segmented into distinct stages: growing LEDs on separate substrates, transferring arrays to an intermediate substrate, then transferring from intermediate to final control circuitry substrate. This segmentation allows optimization of each stage independently, improving overall process efficiency and reliability.
2Ease of manufacture
If entire LED array with original substrate is bonded to control circuitry using metal bonding, then alignment is simplified, but light cross-talk occurs and thermal mismatch generates stress at bonding interface
Solution Approach 1:
The patent extracts and removes the original LED substrates after transferring the LED arrays to an intermediate substrate. This removal eliminates the source of light cross-talk and reduces thermal mismatch stress, while the intermediate substrate provides a stable bonding interface to the control circuitry substrate.
Solution Approach 2:
An intermediate substrate is introduced as a mediator between the LED arrays and the control circuitry substrate. This intermediate layer facilitates proper alignment and bonding while isolating the system from thermal mismatch issues and preventing light cross-talk, as the original problematic substrates are removed.
3Adaptability or versatility
If multi-color display panels use different color LEDs grown on different substrate materials, then color diversity is achieved, but manufacturing complexity increases significantly
Solution Approach 1:
The intermediate substrate serves multiple functions: it receives LED arrays from different substrate materials, provides a uniform bonding interface to the control circuitry substrate, and enables integration of multi-color LEDs without increasing manufacturing complexity. This universal platform handles diverse LED types uniformly.
Solution Approach 2:
The patent segments the manufacturing process so that different color LEDs can be grown on their respective optimized substrate materials separately, then transferred as arrays to the intermediate substrate. This segmentation allows each LED type to be optimized independently while simplifying the overall integration process through the intermediate substrate.
Data Source
AI summary
A micro-display chip comprises a micro light-emitting diode (micro-LED) array having a plurality of micro-LEDs. A micro-LED includes a substrate having a circuit and a metal layer disposed on the substrate and in electrical contact with the circuit. The micro-LED further includes a light emitting layer disposed on the metal layer and an isolation layer covering a sidewall of the light emitting layer. An opening is formed in the isolation layer and exposes at least a portion of a surface of the light emitting layer. The micro-LED further includes a conductive layer disposed on the isolation layer, wherein at least a portion of the conductive layer is disposed in the opening and in contact with the at least a portion of the surface of the light emitting layer.