Micro LED Sidewall Repair via Dual-Stage ALD
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Solution Overview
Problem
Micro LED displays face significant challenges due to non-radiative recombination on the etched sidewalls of mesas, which greatly affects their luminous brightness and efficiency, given the small size of the micro LEDs and the defects formed during the etching process.
Innovation Solution
A manufacturing method involving atomic-layer deposition (ALD) with two stages of different temperatures to repair defects and form a passivation layer on the etched sidewalls of micro LEDs, using a repair gas that may be transformed into plasma to enhance the repair process, thereby reducing non-radiative recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching process is used to form mesas on LED epitaxial wafer, then micro LED structures are created, but defects and dangling bonds occur on sidewalls causing non-radiative recombination
Solution Approach 1:
The patent applies preliminary action by performing defect repair treatment on the etched sidewalls before completing the micro LED manufacturing process. The repair process addresses dangling bonds and defects on the sidewalls of mesas after etching but before final device assembly, preventing non-radiative recombination from degrading luminous brightness. This preliminary intervention ensures that the sidewall defects are corrected early in the manufacturing sequence.
2Length of moving object
If micro LED size is reduced to increase display resolution, then display density improves, but non-radiative recombination effect on luminous brightness becomes extremely large
Solution Approach 1:
The patent applies local quality by targeting the sidewall regions of micro LED mesas for selective defect repair. The repair treatment is localized to the etched sidewalls where dangling bonds and defects occur, rather than treating the entire micro LED structure. This localized approach addresses the specific problem area (sidewall defects) while preserving the overall miniaturized structure, allowing small micro LED size to be maintained without sacrificing luminous brightness.
3Device complexity
If traditional single-stage ALD is used to form passivation layer, then manufacturing process is simple, but defect repair effectiveness is insufficient
Solution Approach 1:
The patent applies segmentation by dividing the atomic layer deposition (ALD) process into two distinct stages: a first ALD stage for defect repair and a second ALD stage for passivation layer formation. Each stage uses different process parameters optimized for its specific function. The first stage targets defect repair on sidewalls, while the second stage forms the protective passivation layer. This segmented approach improves defect repair effectiveness compared to a single-stage process, while maintaining reasonable manufacturing complexity.
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 method effectively improves the luminous brightness and efficiency of micro LEDs by repairing defects and forming a passivation layer on the etched sidewalls, significantly reducing non-radiative recombination and enhancing their performance.
Implementation Method 1
transfer a repair gas into the reaction chamber, wherein the repair gas reacts with the etched LED epitaxial wafer
Implementation Method 2
perform an ALD to the etched LED epitaxial wafer, to form a passivation layer on the etched sidewalls
Implementation Method 3
transform the repair gas into a plasma to enhance the repair process
Data Source
AI summary
The present disclosure is a manufacturing method for reducing non-radiative recombination of micro LED. At least one etched LED epitaxial wafer includes a plurality of etching grooves and mesas, an etched sidewall of the mesa includes a stack of a first type semiconductor layer, an active layer and a second type semiconductor layer. Two stages of ALD are performed on the etched LED epitaxial wafer with different temperature ranges. The first ALD can be used to repair dangling bonds and defects on the etched side walls of the mesa, and the second ALD can be used to form a passivation layer on the etched side walls of the mesa. By the manufacturing method of the present disclosure, non-radiative recombination of the micro LED can be reduced, and the luminous brightness and luminous efficiency of the micro LED can be improved.