Micro-LED Contact Electrode Self-Alignment for Corrosion-Free Assembly
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Solution Overview
Problem
Micro-LED display manufacturing faces challenges in quickly and accurately transferring millions of micro-LEDs, leading to issues with assembly wiring corrosion, electrical short circuits, and misalignment, which affect luminous efficiency and reliability.
Innovation Solution
A display device and manufacturing method that self-aligns a contact electrode to the first semiconductor layer of the micro-LED, using a substrate with spaced assembly wiring, a planarization layer, and a passivation layer to prevent corrosion and ensure electrical connection only to the first semiconductor layer, minimizing movement and external contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If self-assembly method is used to transfer micro-LEDs in fluid, then assembly rate is improved, but assembly wiring corrosion occurs causing electrical short circuits
Solution Approach 1:
The harmful effect of fluid corrosion on assembly wiring is eliminated by extracting the wiring from the fluid environment. The patent achieves this by forming a contact electrode that extends through the planarization layer to contact the first semiconductor layer, thereby shortening the assembly wiring length and removing the exposed wiring portions that would be corroded by the fluid during self-assembly.
Solution Approach 2:
The contact electrode is formed in advance before the self-assembly process. By preliminarily forming the contact electrode that connects the assembly wiring to the first semiconductor layer, the wiring is protected from fluid corrosion before the corrosion problem can occur during assembly.
2Reliability
If contact electrode is formed to connect assembly wiring and light emitting device, then electrical connection is improved, but luminous efficiency decreases due to contact electrode formation on second semiconductor layer
Solution Approach 1:
The contact electrode is selectively formed only in the region where it is needed for electrical connection. The patent specifies that the contact electrode contacts the first semiconductor layer through the planarization layer opening, and the second semiconductor layer is exposed outside the opening. This localized formation ensures electrical connection while preventing the contact electrode from covering the light-emitting second semiconductor layer, thereby maintaining luminous efficiency.
3Manufacturing precision
If micro-LEDs are transferred using pick and place or laser lift-off, then transfer precision is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent enables the micro-LEDs to self-align and self-assemble onto the substrate using the electric field between the first and second assembly wirings. The light emitting device automatically positions itself with the contact electrode during the self-assembly process, eliminating the need for complex external pick-and-place or laser lift-off equipment, thereby reducing manufacturing complexity while maintaining precision.
4Ease of manufacture
If assembly wiring is exposed in fluid during self-assembly, then self-assembly process is simplified, but corrosion and short circuit defects increase
Solution Approach 1:
The assembly wiring is extracted from the corrosive fluid environment by forming the contact electrode that connects the wiring to the first semiconductor layer. This shortens the wiring length and removes the exposed portions that would be corroded by the fluid, thereby eliminating the harmful corrosion effect while maintaining the simplicity of the self-assembly process.
Data Source
AI summary
The manufacturing method of the display device according to the embodiment includes a step of self-aligning the light emitting device inside the opening of the planarization layer overlapping the first assembly wiring and the second assembly wiring, a step of sequentially forming a conductive layer and an organic layer on a planarization layer and a light emitting device, a step of ashing the organic layer to remove the second part on the first part of the organic layer, and a step of forming a contact electrode by etching the conductive layer corresponding to the second part, wherein the contact electrode is in contact with the side of the first semiconductor layer below the light emitting device.