Patterned Dissociation Interfaces for Micro-Transfer Printing
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Solution Overview
Problem
Current methods for separating micro-devices from wafers do not provide transfer printable devices, especially for various wafer types, and often require handle substrates or multiple transfer steps, which are costly and inefficient.
Innovation Solution
The use of electromagnetic irradiation to create patterned dissociation interfaces between micro-devices and the growth substrate, allowing for the formation of anchors and tethers that enable micro-transfer printing without handle substrates or multiple transfer steps, using a growth substrate material that is more transparent to the irradiation than the device materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional separation methods (dicing, laser lift off) are used to separate micro-devices from wafers, then devices can be removed from the substrate, but the devices cannot be directly transfer printed to destination substrates without additional handle substrates or multiple transfer steps
Solution Approach 1:
The patent applies preliminary action by pre-forming anchors and tethers on the growth substrate before device separation. The anchors are created through selective dissociation of the interface between the device material and growth substrate, while tethers physically connect the devices to these anchors. This preliminary structuring enables direct micro-transfer printing without requiring subsequent handle substrate bonding or multiple transfer steps, thereby simplifying the overall manufacturing process.
Solution Approach 2:
The patent introduces anchors and tethers as intermediary structures that mediate the transfer process. The anchors serve as attachment points on the growth substrate, while the tethers act as physical connectors between the devices and anchors. These intermediaries enable the device to be selectively released and transferred to a destination substrate through micro-transfer printing, eliminating the need for complex handle substrate procedures.
2Reliability
If handle substrates or multiple stamp transfer steps are used to achieve device transfer, then devices can be transferred to destination substrates, but the manufacturing cost and process complexity increase
Solution Approach 1:
The patent extracts the essential transfer functionality from complex multi-step processes by directly forming anchors and tethers on the growth substrate. This eliminates the need to use handle substrates as intermediaries or to perform multiple stamp transfer steps. The extraction of this core function simplifies the manufacturing process while maintaining reliable device transfer capability, thereby reducing both cost and complexity.
3Manufacturing precision
If the growth substrate material is more transparent to electromagnetic irradiation than the device materials, then patterned dissociation interfaces can be formed to create anchors, but selective dissociation requires precise control of irradiation parameters
Solution Approach 1:
The patent applies local quality by creating spatially varying properties in the interface between the device and growth substrate. The electromagnetic irradiation selectively dissociates portions of this interface based on local material properties and irradiation intensity distribution. This results in anchors being formed at specific locations where selective dissociation occurs, while other areas maintain their adhesion. The local quality approach enables precise anchor formation through controlled spatial variation of dissociation.
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 construction of transfer printable micro-devices on native growth substrates, facilitating the assembly of low-cost, high-performance micro-device arrays like micro-LEDs directly onto destination substrates, such as plastic or glass, without the need for additional manufacturing steps.
Implementation Method 1
The device structures incorporate a device material that is different from the growth material and that is relatively less transparent to a desired frequency of electromagnetic radiation than the growth material. Irradiation with a desired frequency of electromagnetic radiation partially separates the micro-devices from the growth substrate, thereby forming anchors between the micro-devices and the growth substrate
Data Source
AI summary
A transfer-printable (e.g., micro-transfer-printable) device source wafer comprises a growth substrate comprising a growth material, a plurality of device structures comprising one or more device materials different from the growth material, the device structures disposed on and laterally spaced apart over the growth substrate, each device structure comprising a device, and a patterned dissociation interface disposed between each device structure of the plurality of device structures and the growth substrate. The growth material is more transparent to a desired frequency of electromagnetic radiation than at least one of the one or more device materials. The patterned dissociation interface has one or more areas of relatively greater adhesion each defining an anchor between the growth substrate and a device structure of the plurality of device structures and one or more dissociated areas of relatively lesser adhesion between the growth substrate and the device structure of the plurality of device structures.