Micro-LED Electrode Height Equalization via Groove Structure
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Solution Overview
Problem
Micro-LED displays experience bonding failures between the LED elements and the driving circuit substrate due to height discrepancies between n-electrodes and p-electrodes formed in the same process, leading to inconsistent bonding and reduced yield.
Innovation Solution
A micro-LED display design featuring a groove surrounding the light-emitting elements, with n-electrodes formed annularly along the groove's bottom surface and p-electrodes on a transparent electrode, ensuring both electrodes are at the same height and preventing bonding failures by creating a non-light emitting outer peripheral region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If n-electrode and p-electrode are formed in the same process, then manufacturing efficiency is improved, but bonding reliability deteriorates due to height differences between electrodes
Solution Approach 1:
The patent introduces a groove structure that adds a vertical dimension to the electrode formation process. By forming the n-electrode on the bottom surface of the groove and the p-electrode on the top surface of the transparent electrode, the groove compensates for the height difference, allowing both electrodes to be formed in the same process while maintaining equal heights for reliable bonding.
Solution Approach 2:
The groove acts as an intermediary structure that mediates the height difference between the n-electrode and p-electrode. By providing a lower base for the n-electrode through the groove, the structure enables both electrodes to reach the same final height, resolving the bonding reliability issue while maintaining manufacturing efficiency.
2Reliability
If n-electrode is formed to contact exposed n-type semiconductor layer, then electrical connection is improved, but electrode height uniformity deteriorates causing bonding failure
Solution Approach 1:
The patent segments the semiconductor structure by introducing a groove that separates the light-emitting central part from the outer peripheral part. This segmentation allows the n-electrode to be formed on the groove bottom surface where it contacts the exposed n-type semiconductor layer, while the groove depth is controlled to ensure the n-electrode height matches the p-electrode height, thus maintaining both electrical connection reliability and height uniformity.
Solution Approach 2:
The patent changes the geometric parameters of the structure by introducing a groove with specific depth and dimensions. By adjusting the groove depth, the n-electrode position is lowered to compensate for its otherwise excessive height, enabling height uniformity with the p-electrode while maintaining contact with the n-type semiconductor layer for reliable electrical connection.
3Measurement precision
If micro-LED element is miniaturized, then display resolution is improved, but bonding precision deteriorates due to height differences
Solution Approach 1:
For miniaturized micro-LED elements, the groove structure provides a vertical dimension solution that compensates for height differences without increasing the planar footprint. This allows the electrodes to be formed in the same process with equal heights, maintaining bonding precision even as the element size is reduced for higher display resolution.
Solution Approach 2:
The groove is formed preliminarily before electrode deposition, pre-establishing the height compensation structure. This preliminary action ensures that when the n-electrode and p-electrode are formed in the same process, they will have equal heights, thereby maintaining bonding precision in miniaturized elements without requiring additional height adjustment steps.
Data Source
AI summary
The present invention provides a LED display miniaturized while suppressing bonding failure of electrode. A micro-LED element includes a substrate, a semiconductor layer, a p-electrode, and an n-electrode. The semiconductor layer has a plurality of light-emitting parts arranged in a matrix and having a light-emitting layer. The p-electrodes are arranged in a matrix corresponding to the positions of the light-emitting parts. The n-electrode is disposed annularly surrounding the light-emitting parts and the p-electrodes. The semiconductor layer has a central part and an outer peripheral part. The outer peripheral part has a p-type semiconductor layer.