Micro LED Mesa Isolation Structure for Reduced Cross-Talk
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Solution Overview
Problem
Conventional micro LEDs face challenges such as reduced light extraction efficiency due to spaces between adjacent mesas, nonradiative recombination at mesa sidewalls, and cross-talk between adjacent LEDs, which affect their performance and efficiency.
Innovation Solution
The micro LED structure incorporates a mesa structure, a trench, and an ion implantation fence with a higher electrical resistance than the mesa structure, which reduces nonradiative recombination and allows for a decreased space between adjacent mesas, enhancing light extraction efficiency and integration level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ion implantation is performed directly on the mesa structure to form a fence, then manufacturing process is simpler, but the fence cannot be fully surrounded by the trench leading to incomplete isolation
Solution Approach 1:
The patent segments the fence formation process into two distinct stages: first forming a preliminary fence through ion implantation on the mesa structure, then completing the isolation by forming a second fence portion within the trench that fully surrounds the mesa structure. This segmentation resolves the contradiction by allowing each stage to fulfill its specific function without compromising overall isolation completeness.
Solution Approach 2:
The patent applies preliminary action by first forming the ion implanted fence on the mesa structure before trench formation, creating a preliminary isolation barrier that guides subsequent processing. This preliminary fence serves as a foundation for the complete isolation structure, ensuring that the final fence fully surrounds the mesa structure while maintaining manufacturing feasibility.
2Manufacturing precision
If trench depth is increased to fully surround the mesa structure, then fence isolation completeness improves, but manufacturing complexity increases
Solution Approach 1:
The patent segments the fence into two portions: a first fence portion formed through ion implantation on the exposed mesa structure, and a second fence portion formed within the trench after it extends through the mesa. This segmentation allows the trench to be formed to a practical depth while still achieving complete isolation through the combined effect of both fence portions.
Solution Approach 2:
The patent introduces an intermediary approach where the ion implanted fence serves as a preliminary structure that guides and complements the trench formation. The combination of the ion implanted fence and the trench-formed fence creates a complete isolation barrier without requiring the trench to alone perform the complete isolation function, thereby reducing manufacturing complexity.
3Ease of manufacture
If single-step ion implantation is used, then manufacturing process is simpler, but fence electrical resistance is insufficient for complete isolation
Solution Approach 1:
The patent segments the fence formation into two distinct ion implantation steps: first implanting ions on the mesa structure to create a preliminary high-resistance fence, then implanting additional ions within the trench to create a second high-resistance fence portion. This segmentation allows each implantation step to contribute to the overall electrical isolation, achieving complete isolation with appropriate resistance without requiring excessively complex single-step processes.
Solution Approach 2:
The patent applies preliminary action by performing the first ion implantation to create a preliminary fence with sufficient electrical resistance before trench formation. This preliminary high-resistance structure serves as a foundation that, when combined with the second fence portion formed in the trench, achieves complete electrical isolation while maintaining manufacturing simplicity through staged processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves the active light emitting efficiency, increases the integration level of micro LEDs, and enhances image quality by minimizing nonradiative recombination and cross-talk.
Implementation Method 1
an ion implantation fence separated from the mesa structure, the trench extending up through the first type semiconductor layer and extending up into at least part of the first type cap layer; and the ion implantation fence is formed around the trench and the trench is formed around the mesa structure
Data Source
Figure 1A~1C
Figure 1D~1F
Figure 2~3
AI summary
A micro LED includes a first type semiconductor layer; and a light emitting layer formed on the first type semiconductor layer; a first type cap layer formed at a bottom surface of the light emitting layer and between the first type semiconductor layer and the light emitting layer; wherein the first type semiconductor layer includes a mesa structure, a trench, and a ion implantation fence separated from the mesa structure, the trench extending up through the first type semiconductor layer and extending up into at least part of the first type cap layer; and the ion implantation fence is formed around the trench and the trench is formed around the mesa structure; wherein an electrical resistance of the ion implantation fence is higher than an electrical resistance of the mesa structure .