Micro-LED Transfer via Laser Lift-Off and Contactless Placement
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Solution Overview
Problem
The existing methods for transferring micro-LEDs from a donor wafer to a receiving substrate are complex and costly, requiring multiple transfers and imposing thermal limitations that can degrade micro-LED performance, particularly due to the need for a complicated transfer head array and temporary bonding processes.
Innovation Solution
A method involving laser lift-off of micro-LEDs from a laser-transparent original substrate, where the micro-LEDs are brought into contact with pads on a receiving substrate through contactless actions such as gravity, electrostatic force, or electromagnetic force, eliminating the need for a complex pick-up system and reducing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic pick-up with transfer head array is used, then micro-LED transfer can be achieved, but device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent extracts and removes the complex transfer head array from the system by using laser lift-off technology. Instead of using electrostatic pick-up with transfer heads, the method directly lifts micro-LEDs from the donor substrate using laser irradiation and transfers them to the receiving substrate through contactless action, eliminating the intermediary transfer head array entirely.
Solution Approach 2:
The patent replaces the mechanical electrostatic pick-up system with an optical field-based laser lift-off system. The laser beam creates a localized molten layer that propels micro-LEDs off the donor substrate without mechanical contact, substituting complex mechanical transfer heads with a simpler optical field approach.
2Reliability
If phase change with transfer head array is used, then micro-LED pick-up is enabled, but thermal budget is limited below 350°C which degrades micro-LED performance
Solution Approach 1:
The patent applies local quality by concentrating laser energy at the specific location where micro-LED detachment is needed. The laser irradiation creates a localized molten layer only at the donor substrate interface, allowing high-temperature processing locally without heating the entire micro-LED structure or receiving substrate, thus avoiding thermal budget limitations.
Solution Approach 2:
The patent converts the potentially harmful thermal effect into a beneficial mechanism. The laser-induced localized melting, which could be harmful if applied broadly, is used beneficially to create a molten layer that propels micro-LEDs off the donor substrate. This controlled thermal effect enables transfer without subjecting the micro-LED to excessive overall thermal stress.
3Reliability
If two transfers (donor wafer to carrier wafer, then carrier wafer to receiving substrate) are used, then micro-LED transfer is completed, but manufacturing time increases and productivity decreases
Solution Approach 1:
The patent merges the transfer process into a single step by combining donor substrate removal and micro-LED placement onto the receiving substrate. The laser lift-off method directly transfers micro-LEDs from the donor substrate to the receiving substrate in one operation, eliminating the intermediate carrier wafer step and consolidating multiple transfer operations into a single integrated process.
Solution Approach 2:
The patent eliminates the intermediary carrier wafer from the transfer process. Instead of using a carrier wafer as an intermediate transfer medium, the method enables direct transfer from donor substrate to receiving substrate through laser-induced molten layer propulsion and contactless action, removing the unnecessary intermediary step that reduces productivity.
4Reliability
If transfer head array is used, then micro-LED can be picked up, but additional manufacturing cost is incurred
Solution Approach 1:
The patent replaces expensive, complex transfer head arrays with a simpler, more cost-effective laser lift-off system. The laser system uses optical fields and localized thermal effects that require minimal hardware infrastructure compared to precision electrostatic transfer heads, significantly reducing equipment investment and manufacturing costs while maintaining transfer capability.
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 transfer process, reduces costs, and maintains high micro-LED quality by avoiding thermal budget limitations and complex pick-up systems, enabling efficient and reliable transfer with improved throughput and performance.
Implementation Method 1
irradiating the original substrate with laser from the original substrate side to lift-off the micro-LEDs from the original substrate
Implementation Method 2
the laser beam creates a localized molten layer that propels micro-LEDs off the donor substrate
Implementation Method 3
the contactless action is electrostatic force. Preferably, the electrostatic force is applied by applying voltage to the pads
Implementation Method 4
the micro-LEDs contain magnetic substance, and the contactless action is electromagnetic force
Data Source
AI summary
The present invention discloses a transferring method, a manufacturing method, a device and an electronic apparatus of micro-LED. The method for transferring micro-LED comprises: forming micro-LEDs on a laser-transparent original substrate; irradiating the original substrate with laser from the original substrate side to lift-off the micro-LEDs from the original substrate; bring the micro-LEDs into contact with pads preset on a receiving substrate through a contactless action.