Micro-LED Transfer Using Laser Protection Layer
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Solution Overview
Problem
Current micro-LED transfer methods face high manufacturing costs and reliability issues due to thermal loadings and potential damage to circuitry on the receiving substrate during laser lift-off, particularly with oversized or undersized laser beams.
Innovation Solution
A micro-LED transfer method involving a protection layer on the carrier or receiving substrate to prevent laser irradiation from reaching the circuitry, using a mask, patterned polymer, or conductive layer to shield the circuitry, allowing precise laser alignment and reducing the risk of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an oversized laser beam is used for lift-off, then the laser can easily cover the micro-LED area, but the laser will leak and reach the circuitry on the receiving substrate causing potential damage
Solution Approach 1:
A mask layer is introduced as an intermediary component between the laser beam and the circuitry on the receiving substrate. The mask layer absorbs or blocks the laser energy, preventing it from reaching and damaging the circuitry while allowing the lift-off process to proceed effectively.
Solution Approach 2:
The system is segmented into distinct functional zones: the micro-LED area where lift-off occurs, the circuitry area that requires protection, and the mask layer that separates these zones. This segmentation allows the laser beam to be oversized for easy alignment while the mask confines the laser interaction to only the intended micro-LED region.
2Object-affected harmful factors
If an undersized laser beam is used for lift-off, then the circuitry is protected from laser damage, but high precision bonding and laser alignment are required which becomes a bottleneck for small micro-LED transfer
Solution Approach 1:
The mask layer serves as a mediator that allows the use of a larger, more easily aligned laser beam while still protecting the circuitry. The mask absorbs the laser energy in the circuitry region, enabling relaxed alignment tolerances without compromising circuit safety.
Solution Approach 2:
The mask layer is prepared in advance on the receiving substrate before the laser lift-off process. This preliminary preparation ensures that the circuitry is already protected when the laser is applied, eliminating the need for high-precision alignment during the actual transfer operation.
3Productivity
If complicated transfer head arrays such as electro-static head array or electro-magnetic head array are used, then massive micro-LED array can be transferred, but manufacturing cost increases and reliability issues arise due to multiple thermal loadings
Solution Approach 1:
The patent replaces complex mechanical transfer head arrays with a simpler laser-based lift-off system. By using laser energy to detach micro-LEDs from the carrier substrate, the system eliminates the need for complicated electro-static or electro-magnetic head arrays, thereby reducing manufacturing cost and improving reliability by minimizing thermal loadings on the transfer mechanism.
4Object-affected harmful factors
If a mask layer is added to protect circuitry during laser lift-off, then laser damage to circuitry is prevented, but the device complexity increases
Solution Approach 1:
The mask layer is a simple intermediary component that can be deposited as a thin film on the receiving substrate. While it adds a layer to the system, the mask's fabrication and integration are straightforward processes that do not significantly complicate the overall device structure or transfer process.
Solution Approach 2:
The mask layer can be designed as a consumable or temporary component that serves its protective function during the transfer process and can be removed or replaced if needed. This approach keeps the mask simple and inexpensive, minimizing the impact on device 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
The protection layer effectively prevents laser damage to the circuitry, simplifies the transfer process, and enhances the precision and reliability of micro-LED transfer, especially for small micro-LEDs, while reducing manufacturing complexity and costs.
Implementation Method 1
irradiating the micro-LEDs to be transferred with laser from the first surface to lift-off the micro-LEDs to be transferred from the carrier substrate
Implementation Method 2
irradiating the micro-LEDs to be transferred with laser from the first surface to lift-off the micro-LEDs to be transferred from the carrier substrate
Implementation Method 3
the protection layer is configured to protect the third surface from the irradiation of the laser
Data Source
AI summary
A micro-LED transfer method, manufacturing method and device are provided. The micro-LED transfer method comprises: obtaining a laser-transparent carrier substrate having a first surface and a second surface with micro-LEDs; forming a protection layer on at least one of the first surface and the second surface and a third surface of a receiving substrate, wherein the third surface is to receive the micro-LEDs to be transferred via pads; bringing the micro-LEDs to be transferred into contact with the pads on the third surface; and irradiating the micro-LEDs to be transferred with laser from the first surface to lift-off the micro-LEDs to be transferred from the carrier substrate wherein the protection layer configured to protect the third surface from the irradiation of the laser.