Micro LED Array Fabrication via Epitaxial Growth on Signal Line Grid
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Solution Overview
Problem
The existing methods for fabricating micro LED display panels are hindered by the time-consuming and error-prone pick-and-place transfer process of micro LEDs, leading to misalignment and defects in the display panel.
Innovation Solution
A method is developed where micro LEDs are directly fabricated in an array substrate using a grid of signal lines for epitaxial growth, eliminating the need for transfer and enhancing emission efficiency with an inverted trapezoidal growth profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pick-and-place transfer process is used to transfer micro LEDs from a growth substrate to an array substrate, then the micro LEDs can be positioned in the array substrate, but the process is time-consuming and leads to misalignment and defects
Solution Approach 1:
The patent merges the growth substrate and array substrate into a single integrated substrate. The micro LEDs are grown directly on the array substrate in their final positions, eliminating the need for separate transfer processes. This integration resolves the contradiction by achieving both high alignment precision (since micro LEDs are grown in-place) and reduced fabrication time (by eliminating the transfer step).
Solution Approach 2:
The patent applies preliminary action by pre-defining the grid pattern and signal line structures on the array substrate before growing the micro LEDs. The growth substrate is designed with pre-formed electrode patterns that align with the array substrate grid, ensuring precise positioning without requiring post-transfer alignment operations. This preliminary preparation eliminates misalignment issues and reduces overall fabrication time.
2Reliability
If the pick-and-place transfer process is used, then micro LEDs can be transferred to the array substrate, but the process is error-prone and causes defects in the display panel
Solution Approach 1:
By merging the growth and array functions into a single substrate, the patent eliminates the transfer process that introduces errors and defects. The micro LEDs are grown directly on the array substrate with precise spatial control, removing the mechanical handling steps that cause damage and misalignment. This significantly improves reliability while reducing fabrication process complexity.
Solution Approach 2:
The growth substrate structure is designed to self-align with the array substrate through integrated grid patterns and signal lines. The epitaxial growth process automatically positions micro LEDs at correct locations based on pre-formed electrode patterns, eliminating the need for complex external alignment and placement operations. This self-aligning mechanism reduces both process complexity and defect rates.
3Use of energy by moving object
If conventional fabrication methods are used, then micro LEDs can be manufactured, but the emission efficiency is reduced due to non-optimized growth profiles
Solution Approach 1:
The patent applies local quality by creating an inverted trapezoidal growth profile specifically at the micro LED structures, which optimizes light emission characteristics. The growth conditions are locally controlled to achieve this specific shape, with wider bases and narrower tops, improving emission efficiency. This localized optimization does not complicate the overall fabrication process since it is achieved through controlled epitaxial growth on the integrated substrate.
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 approach simplifies the fabrication process, reduces defects, and significantly enhances the emission efficiency of micro LEDs, making it suitable for large-scale production.
Implementation Method 1
A surface of the plurality of signal lines away from the base substrate is uncovered during depositing the semiconductor material, and the plurality of signal lines form a grid for facilitating epitaxial growth of the semiconductor material.
Data Source
Figure 1A
Figure 1B~1C
Figure 2A
AI summary
A method of fabricating a micro light emitting diode (micro LED) array substrate having a plurality of micro LEDs is provided. The method includes forming a plurality of signal lines on a base substrate (10); depositing a semiconductor material on the base substrate (10) to form a semiconductor material layer; and patterning the semiconductor material layer to form a semiconductor layer (500) of the plurality of micro LEDs. A surface of the plurality of signal lines away from the base substrate (10) is uncovered during depositing the semiconductor material. The plurality of signal lines form a grid for facilitating epitaxial growth of the semiconductor material.