LED Display Electrode Layout for Self-Aligned Sub-Pixel Connections
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Solution Overview
Problem
Display devices using LEDs face challenges with misalignment between connection electrodes, leading to short defects and reduced light efficiency, particularly due to the complexity of aligning semiconductor layers during manufacturing.
Innovation Solution
A display device design that includes a first and second connection electrode self-aligned with semiconductor layers using planarization layers of smaller thickness, and an ashing process to minimize misalignment errors, along with a reflective electrode structure to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional alignment processes are used for connection electrodes and semiconductor layers, then manufacturing complexity is reduced, but misalignment occurs leading to short defects
Solution Approach 1:
The patent introduces planarization layers as intermediary structures between the connection electrodes and semiconductor layers. These planarization layers provide a flat surface that enables precise alignment and self-positioning of the connection electrodes relative to the semiconductor layers, thereby achieving high alignment precision without complex alignment processes. The planarization layers act as mediators that simplify the alignment operation while maintaining manufacturing precision.
2Reliability
If connection electrodes are formed without planarization layers, then manufacturing process is simpler, but misalignment between electrodes and semiconductor layers occurs causing short defects
Solution Approach 1:
The patent applies planarization processes before forming the connection electrodes to create a flat surface in advance. This preliminary action of planarizing the surface ensures that when connection electrodes are subsequently formed, they automatically achieve precise alignment with the semiconductor layers, preventing misalignment defects. The preliminary planarization action eliminates the need for complex alignment procedures during electrode formation.
3Illumination intensity
If light emitting elements are placed directly on substrates without adhesive layers, then manufacturing steps are reduced, but light extraction efficiency decreases
Solution Approach 1:
The patent introduces adhesive layers with specific optical properties at the interface between light emitting elements and substrates. These adhesive layers possess localized optical characteristics that enhance light extraction efficiency at this specific interface, while the rest of the device structure remains relatively simple. The local quality of the adhesive layer optimizes light extraction without requiring complex modifications throughout the entire device structure.
Data Source
AI summary
According to an aspect of the present disclosure, a display device includes a substrate in which a plurality of sub-pixels is defined, a light emitting element disposed on each of the plurality of sub-pixels, and a first connection electrode surrounding a first semiconductor layer disposed at a lower part of the light emitting element, a second connection electrode in contact with a top surface of the light emitting element, a first planarization layer disposed between the first connection electrode and the second connection electrode and having a smaller thickness than the first semiconductor layer of the light emitting element, and a second planarization layer disposed between the first planarization layer and the second connection electrode.