Photoresist Electrode Layout for Low-Reflectivity Micro LED Bonding
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Solution Overview
Problem
Conventional Micro LED and Mini LED display devices face challenges in achieving good display quality due to high reflectivity of metal traces and topography issues caused by low-reflection layers, leading to poor electrical connections during the mass transferring and bonding processes.
Innovation Solution
A display device with a flat photoresist pattern layer is developed, allowing for improved electrical connections between light-emitting elements and electrodes. The photoresist pattern layer is processed in an array fab without the need for a color filter fab transfer, reducing costs and eliminating parasitic capacitance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a resin black matrix or other photoresist materials are adopted as the low reflection layer in the non-display area, then the reflectivity is reduced and aesthetic appearance is improved, but a significant height difference of the topography occurs leading to mutual interference between mass transferring and topography height
Solution Approach 1:
The patent applies local quality by making the photoresist pattern layer have different optical properties in different regions: the first photoresist pattern in the display area has high light transmittance to allow light passage, while the second photoresist pattern in the non-display area has low light transmittance to reduce reflectivity and improve aesthetic appearance. This resolves the contradiction by providing different local functions within the same layer structure.
2Object-affected harmful factors
If black metal is adopted as the low reflection layer, then the reflectivity is reduced, but an effect of parasitic capacitance is caused and an extra photomask process is required
Solution Approach 1:
The patent replaces the durable but problematic black metal layer with a photoresist-based low reflection layer that can be processed and removed or integrated more easily. The photoresist pattern layer serves the temporary function of reducing reflectivity during manufacturing and can be adjusted or removed without causing parasitic capacitance issues, simplifying the overall device structure and process.
Solution Approach 2:
The patent substitutes the metallic material system with an organic photoresist material system. Instead of using conductive black metal that causes parasitic capacitance, the invention uses photoresist materials that can be patterned and processed through photolithography, replacing the mechanical/electrical function of black metal with a chemical/optical-based solution.
3Object-affected harmful factors
If a resin black matrix is adopted, then the reflectivity is reduced, but a derived cost from the transfer to the color filter fab is generated
Solution Approach 1:
The patent merges the low reflection layer function with the existing photoresist processing steps in the array fab. By integrating the formation of the photoresist pattern layer into the standard photolithography process flow, the invention eliminates the need for separate transfer processes to the color filter fab, thereby reducing manufacturing costs while maintaining the reflectivity reduction benefit.
Data Source
AI summary
A display device and a manufacturing method thereof are provided. The display device includes a display area and a non-display area. The display device includes a substrate, an element layer, an electrode pattern layer, a photoresist pattern layer, and a light-emitting element. The element layer is disposed on the substrate. The electrode pattern layer is disposed on the element layer, and the electrode pattern layer includes multiple electrodes. The photoresist pattern layer is disposed on the electrode pattern layer, and the photoresist pattern layer includes a first photoresist pattern disposed corresponding to the display area and corresponding to the electrodes; a second photoresist pattern disposed corresponding to the non-display area and between the electrodes. The light-emitting element is disposed on the photoresist pattern layer and is electrically connected to the electrodes of the electrode pattern layer.