Selective Microdevice Transfer by Donor-Receiver Force Modulation
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Solution Overview
Problem
Current methods for transferring micro devices from a donor substrate to a receiver substrate lack selectivity and efficiency, often resulting in the transfer of unwanted devices and requiring multiple steps due to mismatched pitches and forces.
Innovation Solution
A method involving the alignment of donor and receiver substrates, followed by the modulation of donor and receiver forces to selectively transfer micro devices using techniques such as weakening the donor force, generating a receiver force, and applying a push force, with options including laser lift-off, heating, adhesive, mechanical, electrostatic, and sacrificial layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current transfer methods are used, then micro devices can be transferred from donor substrate to receiver substrate, but selectivity is poor and unwanted devices are transferred
Solution Approach 1:
The patent applies local quality by creating spatially varying adhesive forces through patterned adhesive regions on the donor substrate. Different areas of the substrate have different adhesive properties, allowing selective transfer of specific micro devices while leaving others behind. This is achieved through controlled adhesive deposition patterns that match the desired device selection map.
Solution Approach 2:
The patent employs dynamics by making the adhesive force可调 (adjustable) through controlled release mechanisms. The adhesive bonds can be selectively weakened or broken by applying specific stimuli (thermal, mechanical, or chemical) to transfer only the intended devices. This dynamic control allows the system to transition from a bonded state to a released state selectively.
2Productivity
If multiple transfer steps are used to handle pitch mismatch, then all devices can be transferred, but process complexity and time increase
Solution Approach 1:
The patent applies segmentation by dividing the transfer process into spatially distinct adhesive regions rather than requiring multiple sequential transfers. Different pitch requirements are handled simultaneously through different adhesive patterns on the same substrate, eliminating the need for multiple alignment and transfer steps.
Solution Approach 2:
The patent achieves universality by creating a single adhesive patterned substrate that can handle multiple pitch requirements simultaneously. The same donor substrate with patterned adhesive can transfer devices at different pitches to different receiver substrates in one operation, making the transfer mechanism multi-functional.
3Stability of the object's composition
If strong donor force is used to hold micro devices, then devices remain stable on donor substrate, but selective transfer becomes difficult
Solution Approach 1:
The patent applies local quality by creating spatially varying adhesive forces through patterned adhesive regions on the donor substrate. Different areas of the substrate have different adhesive properties, allowing selective transfer of specific micro devices while leaving others behind. This is achieved through controlled adhesive deposition patterns that match the desired device selection map.
Solution Approach 2:
The patent employs dynamics by making the adhesive force可调 (adjustable) through controlled release mechanisms. The adhesive bonds can be selectively weakened or broken by applying specific stimuli (thermal, mechanical, or chemical) to transfer only the intended devices. This dynamic control allows the system to transition from a bonded state to a released state selectively.
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
Enables selective and efficient transfer of micro devices, improving the precision and yield of device integration by ensuring only intended devices are transferred, even when pitches differ, and allows for the use of temporary substrates to facilitate easier transfer.
Implementation Method 1
Some embodiments further comprise weakening the donor force using laser lift off
Implementation Method 2
Some embodiments further comprise weakening the donor force by heating an area of the donor substrate
Implementation Method 3
In some embodiments the receiver force is generated by electrostatic attraction between the selected micro devices and the receiver substrate
Implementation Method 4
In some embodiments the heating is performed by passing a current through the contact pads
Data Source
AI summary
What is disclosed is a method of selectively transferring micro devices from a donor substrate to contact pads on a receiver substrate. Micro devices being attached to a donor substrate with a donor force. The donor substrate and receiver substrate are aligned and brought together so that selected micro devices meet corresponding contact pads. A receiver force is generated to hold selected micro devices to the contact pads on the receiver substrate. The donor force is weakened and the substrates are moved apart leaving selected micro devices on the receiver substrate. Several methods of generating the receiver force are disclosed, including adhesive, mechanical and electrostatic techniques.