MicroLED Transfer Adhesive Film for Clean Laser Release
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Solution Overview
Problem
The existing micro light-emitting diode (MicroLED) transfer methods face challenges in yield control and high production costs due to the weakened structure with bridge arms, making it difficult to manage the transfer process effectively.
Innovation Solution
A micro light-emitting element and array design that includes a semiconductor layer sequence, electrical connection layers, and a transfer adhesive film with specific structural features such as a stepped surface, periodic grooves, and material properties to ensure reliable transfer and minimize damage, using a method that involves growth substrate preparation, semiconductor layer formation, and selective transfer with laser decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a weakened structure with bridge arms is used for MicroLED transfer, then the structure provides mechanical support during transfer, but the yield control becomes difficult and production cost increases
Solution Approach 1:
The patent removes the bridge arm structure from the MicroLED design, extracting the problematic mechanical support element that caused yield control difficulties. Instead, the invention uses a transfer adhesive film applied directly to the top surface of the MicroLED, eliminating the need for bridge arms while maintaining transfer capability through adhesive bonding.
Solution Approach 2:
The patent introduces a transfer adhesive film as an intermediary substance between the MicroLED and the transfer substrate. This adhesive film serves as the mediating element that provides mechanical support and enables transfer, replacing the direct structural support previously provided by bridge arms, thereby improving yield control while maintaining necessary mechanical strength.
2Reliability
If the transfer adhesive film covers the entire top surface, then transfer reliability is maximized, but light extraction efficiency decreases due to increased light absorption
Solution Approach 1:
The patent applies the transfer adhesive film selectively to specific regions of the top surface rather than covering the entire surface uniformly. The adhesive is applied to peripheral regions and corners where mechanical support is needed, while leaving the central light-emitting area uncovered or minimally covered, thereby maintaining both transfer reliability and light extraction efficiency through localized adhesive application.
3Reliability
If the thickness of the transfer adhesive film is increased, then transfer reliability improves, but light transmission decreases and production cost increases
Solution Approach 1:
The patent optimizes the thickness parameter of the transfer adhesive film to a specific range (50-500 nanometers) that balances transfer reliability and light transmission. By precisely controlling the adhesive film thickness within this optimized range, the invention achieves sufficient mechanical bonding strength for reliable transfer while maintaining adequate light transmission properties to preserve light extraction efficiency.
4Illumination intensity
If the distance between transfer adhesive film and edge of top surface is reduced, then light extraction efficiency improves, but transfer reliability decreases
Solution Approach 1:
The patent implements a spatially varying adhesive distribution where the transfer adhesive film is positioned at specific distances from the edges (1-10 micrometers) and with varying thickness or density across different regions. This localized adhesive placement provides mechanical support at critical peripheral areas while leaving the central light-emitting region accessible for optimal light extraction, thereby balancing transfer reliability and light extraction efficiency through non-uniform adhesive distribution.
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
The solution provides a high-yield micro light-emitting diode chiplet structure with reduced production costs by ensuring precise transfer and protection of the epitaxial layer, improving transfer reliability and light extraction efficiency.
Implementation Method 1
the transfer adhesive film is configured to transmit light with a wavelength ranging from 400 nanometers (nm) to 750 nm, and absorb at least partially light with a wavelength below 350 nm
Implementation Method 2
the transfer adhesive film is configured to transmit light with a wavelength ranging from 400 nanometers (nm) to 750 nm
Implementation Method 3
a surface of the transfer adhesive film facing away from the semiconductor layer sequence has periodic grooves
Data Source
AI summary
A micro light-emitting element, a micro light-emitting array, a transfer method, and a display are provided. The micro light-emitting element has a side surface, a bottom surface and a top surface opposite to the bottom surface, and the top surface is a light-emitting surface. The micro light-emitting element includes a substrate arranged below the bottom surface and a transfer adhesive film covering the top surface. The transfer adhesive film does not exceed an edge of the top surface. During the laser removal of the transfer adhesive film, the adhesive adheres to the top surface and does not fall onto the substrate, thereby avoiding the generation of substrate dirt.