Multi-Color LED Display Substrate Without Transfer Alignment
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Solution Overview
Problem
Current display device manufacturing methods involve complex and time-consuming processes for transferring LEDs onto substrates with driving units, leading to increased costs and defects due to lattice mismatch issues and alignment errors.
Innovation Solution
A non-transfer method where LEDs of different colors are grown on a single substrate using buffer layers to minimize lattice constant differences, allowing for direct formation of driving units and LEDs on the same substrate, thereby simplifying the process and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a transfer method is used to form LEDs on a substrate with driving units, then the LEDs can be formed separately and transferred, but the process becomes complex and time-consuming with increased alignment errors and defects
Solution Approach 1:
The patent merges the LED formation process and driving unit formation process into a single integrated process by forming both LEDs and driving units directly on the same substrate. This eliminates the need for separate LED fabrication and transfer operations, thereby reducing process complexity and improving alignment precision between LEDs and driving units.
Solution Approach 2:
Instead of the conventional approach of forming LEDs separately and transferring them to the substrate, the patent inverts the process by forming both LEDs and driving units simultaneously on the substrate. This inversion eliminates the transfer step entirely, resolving the alignment and complexity issues associated with the traditional transfer method.
2Productivity
If LEDs are transferred onto a substrate, then separate fabrication is possible, but manufacturing time increases due to complex transfer processes
Solution Approach 1:
The patent combines the LED fabrication and driving unit fabrication into a single simultaneous process on the same substrate. This merging eliminates the sequential transfer operations required in conventional methods, thereby reducing manufacturing time and improving overall productivity.
Solution Approach 2:
The patent performs preliminary patterning and formation of both LEDs and driving units on the substrate before final assembly. By preparing both components in advance on the same substrate in a coordinated manner, the need for time-consuming transfer and alignment operations is eliminated, significantly reducing manufacturing time.
3Reliability
If buffer layers are added to minimize lattice constant differences, then LED reliability improves, but device structure becomes more complex
Solution Approach 1:
The patent introduces buffer layers as intermediary structures between the substrate and the LED active regions. These buffer layers serve as mediators to reduce lattice constant differences and dislocation densities, thereby improving LED reliability. The buffer layers are integrated into the overall device structure without requiring separate complex assembly processes.
Solution Approach 2:
The patent modifies the structural parameters of the LED device by incorporating buffer layers with specific thicknesses and material compositions. By changing these parameters, the lattice mismatch between substrate and LED materials is reduced, improving device reliability. The buffer layer parameters are optimized to provide the necessary lattice matching while maintaining a relatively simple overall structure.
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 shortens manufacturing time, reduces defects, and improves yield by eliminating the need for complex transfers and alignment, while enhancing LED reliability through the integration of Zener diodes for static protection.
Implementation Method 1
a difference in lattice constant between a lower portion of the first epitaxial layer and the substrate is greater than a difference between a lower portion of the second epitaxial layer and the substrate
Data Source
AI summary
A display device according to an example of the present disclosure includes a substrate on which a plurality of sub-pixels are defined; a plurality of LEDs including a first LED, a second LED, and a third LED that are disposed in the plurality of respective sub-pixels on the substrate; and at least one buffer layer disposed between the first LED and the substrate, wherein the first LED is in contact with an upper surface of the at least one buffer layer, and the second LED and the third LED are in contact with an upper surface of the substrate. Accordingly, the plurality of LEDs emitting light of different colors using the buffer layer can be respectively formed on one substrate, thereby allow for omission of a transfer process.