Micro LED Transfer Substrate Recess Layout for Laser Lift-Off
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Solution Overview
Problem
The existing methods for mass transferring micro LEDs from a growth substrate to another substrate are limited by the unevenness of the substrate, which affects the transfer rate and yield in display device manufacturing, as non-uniform stress and chemical reactions during the laser lift-off process can be hindered by substrate warpage and nitrogen accumulation.
Innovation Solution
A device with a first substrate having a patterned recess to increase flatness and a second substrate with a support layer and adhesive layer, where the patterned recess on either substrate facilitates gas release and improves the alignment and detachment of micro LEDs during the laser lift-off process, enhancing the transfer rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mass transfer of micro LEDs is performed using conventional substrate methods, then the transfer process can be completed, but the unevenness and warpage of the substrate hinder gas release and chemical reactions during laser lift-off, reducing transfer rate and yield
Solution Approach 1:
The substrate surface is segmented into multiple regions with different properties: a first region (chip-receiving area) with high flatness for chip attachment, and a second region (peripheral area) with patterned recesses for gas release. This segmentation allows simultaneous optimization of both chip transfer quality and laser lift-off efficiency, resolving the contradiction between transfer rate and transfer yield.
Solution Approach 2:
Different regions of the substrate are given different local qualities: the central chip-receiving area maintains high flatness for reliable chip attachment, while the peripheral regions contain patterned recesses that facilitate gas release during laser lift-off. This local differentiation enables the substrate to simultaneously support high transfer yield in the center and high transfer rate through improved gas venting at the periphery.
2Manufacturing precision
If the substrate is made completely flat to improve chip alignment, then alignment precision improves, but gas release during laser lift-off is hindered, reducing transfer rate
Solution Approach 1:
The substrate is divided into functional zones: a central flat region for precise chip alignment and attachment, and peripheral regions with patterned recesses for gas release during laser lift-off. This segmentation allows the substrate to simultaneously provide high alignment precision in the chip-receiving area and high transfer rate through gas venting in the peripheral areas.
Solution Approach 2:
The substrate exhibits local quality differentiation where the chip-receiving area maintains high flatness for manufacturing precision, while peripheral areas contain recesses that enable rapid gas release to improve transfer rate. This local optimization resolves the contradiction between alignment precision and transfer rate.
3Strength
If the substrate is made completely flat to improve chip attachment, then attachment strength improves, but nitrogen accumulation occurs during laser lift-off, reducing transfer yield
Solution Approach 1:
The substrate is segmented into a central attachment region with high flatness for strong chip attachment and peripheral regions with patterned recesses for nitrogen release. This segmentation allows the substrate to simultaneously provide strong chip attachment in the central area and high transfer yield through effective gas venting in the peripheral areas during laser lift-off.
Solution Approach 2:
Different local qualities are assigned to different substrate regions: the chip-receiving area has high flatness for strong attachment strength, while peripheral areas have recesses that prevent nitrogen accumulation and improve transfer yield. This local differentiation resolves the contradiction between attachment strength and transfer yield.
4Productivity
If patterned recesses are added to the substrate to improve gas release, then transfer rate improves, but substrate complexity increases
Solution Approach 1:
Patterned recesses are added only to specific peripheral regions of the substrate where they are needed for gas release, while the central chip-receiving area maintains its simple flat structure for chip attachment. This localized application of complexity minimizes the increase in overall substrate complexity while still achieving improved transfer rate through effective gas venting.
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 solution increases the transfer rate of micro LEDs by ensuring proper alignment and effective gas release, thereby improving the yield and consistency of the micro LED transfer process, reducing substrate warpage, and ensuring successful detachment from the growth substrate.
Implementation Method 1
a first adhesive layer (314) disposed on the second substrate (310)
Implementation Method 2
The patterned recess is disposed on the first surface and spaced apart from the chip-receiving area
Data Source
AI summary
A device of mass transferring chips includes a first substrate, which includes a chip-connecting area configured to connect a chip. The device further includes a second substrate, which includes a support layer and a first adhesive layer. The chip is between the first substrate and the second substrate. The first adhesive layer includes a first surface, a second surface, and a patterned recess. The first surface has a chip-receiving area configured to attach the chip from the first substrate. The second surface is opposite to the first surface and is in contact with a first side of the support layer. The patterned recess is disposed on the first surface and spaced apart from the chip-receiving area.