Micro-LED Pixel Package Layout for Selective DEP Assembly
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Solution Overview
Problem
Current micro-LED display technologies face challenges in quickly and accurately transferring millions of semiconductor light emitting devices due to high transfer error rates and low assembly yields, particularly in achieving simultaneous assembly of red, green, and blue LED chips with heterogeneous materials and non-uniform dielectrophoresis (DEP) forces, which limits their application in UHD TVs, VR, and AR devices.
Innovation Solution
The semiconductor light emitting device package includes a first color LED chip with a recess and a second color LED chip disposed within, both made of different materials, allowing for precise control of DEP forces by using a GaN substrate for the green LED and a GaAs substrate for the red LED, enabling simultaneous assembly of red, green, and blue LEDs with reduced pixel size and increased assembly probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dielectrophoresis is used to assemble R, G, and B LED chips simultaneously, then assembly speed is improved, but DEP selectivity deteriorates because the applied DEP force is similar for all chip types
Solution Approach 1:
The patent applies local quality by creating different assembly hole shapes (circular for R chips, elliptical for G and B chips) and positioning assembly electrodes asymmetrically to generate location-specific DEP force distributions. This ensures that each chip type experiences optimal DEP forces tailored to its geometric characteristics, resolving the selectivity issue while maintaining high assembly speed.
Solution Approach 2:
The patent employs asymmetry by making the assembly hole shapes different for different chip types and arranging assembly electrodes in asymmetric configurations. This creates distinct DEP force patterns that selectively attract the correct chip types to their designated locations, enabling simultaneous assembly of R, G, and B chips with high precision.
2Manufacturing precision
If exclusive chip shapes are made to improve DEP selectivity, then assembly precision is improved, but the gap between chip sizes increases
Solution Approach 1:
The patent makes different parts of the assembly substrate have different qualities by creating location-specific assembly hole shapes matched to each chip type. This allows precise DEP assembly while keeping actual chip sizes uniform, as the shape differentiation is applied only to the assembly holes and electrode configurations, not to the chips themselves.
3Measurement precision
If micro-LED size is reduced to 20μm or less for UHD TV applications, then display resolution is improved, but assembly difficulty increases due to smaller chip dimensions
Solution Approach 1:
The patent replaces mechanical assembly methods with dielectrophoretic assembly, using electric fields to manipulate and position micro-LED chips. This substitution enables precise assembly of 20μm or smaller chips without mechanical handling, thereby achieving high display resolution while maintaining ease of manufacture through automated field-based positioning.
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 enhances the assembly probability and selectivity of LED chips, allowing for smaller pixel sizes and improved assembly speeds, making it suitable for UHD TVs, VR, and AR applications by ensuring exclusivity among LED chips and balancing DEP forces.
Implementation Method 1
a self-assembly type transfer process using dielectrophoresis (DEP) has been attempted
Data Source
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AI summary
Discussed is a semiconductor light emitting device package for a display pixel The semiconductor light emitting device package can include a first semiconductor light emitting device of a first color having a first material and a second semiconductor light emitting device of a second color having a second material disposed on the first semiconductor light emitting device. The first semiconductor light emitting device can include a first semiconductor light emitting structure having an inner recess, and a first-first electrode and first-second electrode layer electrically connected to a first side and a second side of the first semiconductor light emitting structure, respectively. The second semiconductor light emitting device can be disposed in the inner recess of the first semiconductor light emitting device.