Selective Micro Device 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 laser lift-off, heating, adhesive application, mechanical grip, and electrostatic attraction, allowing for precise control over the transfer process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional transfer methods are used, then transfer process is simple, but selectivity is poor and unwanted devices are transferred
Solution Approach 1:
The patent segments the transfer process into distinct phases: alignment phase, contact phase, and separation phase. Each phase uses different force conditions to achieve selective transfer. The donor force and receiver force are independently controlled during each phase, allowing precise selection of which devices to transfer based on their individual force characteristics.
Solution Approach 2:
The patent dynamically adjusts the donor force and receiver force during the transfer process. By varying the magnitude and timing of these forces across different phases (alignment, contact, separation), the system can selectively transfer devices with specific force profiles while leaving others on the donor substrate.
2Productivity
If multiple transfer steps are used to accommodate pitch mismatch, then all devices can be transferred, but productivity decreases and time increases
Solution Approach 1:
The patent introduces the dimension of force control to solve the pitch mismatch problem. Instead of using multiple mechanical transfer steps, the system uses selective force application (donor force and receiver force) to transfer devices directly across pitch differences. This allows single-step transfer while accommodating different pitches through force-based selection.
Solution Approach 2:
The patent changes the force parameters (magnitude, timing, duration) of donor and receiver forces to accommodate pitch mismatch. By adjusting these parameters, devices at different positions and pitches can be selectively transferred in a single operation, eliminating the need for multiple transfer steps.
3Manufacturing precision
If donor force is strong to hold devices, then devices remain stable on donor substrate, but selective transfer becomes difficult
Solution Approach 1:
The patent uses periodic action by applying donor force and receiver force in distinct time phases. During the alignment phase, donor force holds devices strongly. During the transfer phase, receiver force is applied to overcome donor force for selected devices. During the separation phase, donor force is reduced or removed while receiver force maintains hold on transferred devices. This periodic force application enables selective transfer despite strong initial bonding.
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 the selective and efficient transfer of micro devices, improving yield by minimizing the transfer of unwanted devices and reducing the need for multiple transfer steps, while accommodating devices of different heights and pitches.
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
Some embodiments further comprise modulating the receiver force by heating the receiver substrate
Implementation Method 5
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.