Micro Contact Protrusions for Batch Transfer of Micro LED Dies
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Solution Overview
Problem
Conventional methods for transferring micro LEDs face challenges due to the limitations of pick-up heads in handling small micro LED dies, resulting in low yield and inefficiency in processing large quantities, as they struggle to effectively pick and transfer micro LED dies with edge lengths of 100 microns or less.
Innovation Solution
A target substrate with patterned micro contact protrusions is used to facilitate a selective batch pickup procedure, where the micro contact protrusions connect micro semiconductor structures to the substrate body, enabling efficient batch transfer and integration without damaging the structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional pick-up head methods are used to transfer micro LED dies, then individual LED dies can be selected and transferred, but the pick-up head cannot effectively pick up micro LED dies with edge lengths of 100 microns or less due to scale minimization limitations
Solution Approach 1:
The invention segments the transfer process into two distinct stages: first, the pick-up head transfers the entire array of micro LED dies in batch from the source wafer to an intermediate carrier substrate; second, the micro contact printing plate transfers individual micro LED dies from the carrier substrate to the final substrate. This segmentation allows each stage to use appropriately scaled mechanisms, resolving the pick-up head's inability to handle sub-100-micron dies directly.
Solution Approach 2:
The invention introduces an intermediate carrier substrate as a mediator between the source wafer and the final substrate. The carrier substrate receives the full array of micro LED dies in batch and serves as a temporary holding platform, enabling the decoupling of the batch transfer operation from the individual die placement operation. This intermediary structure allows the system to overcome the pick-up head's size limitations.
2Productivity
If individual LED dies are picked and transferred one by one using conventional processes, then each die can be placed precisely, but the process cannot meet the needs of huge amounts of manufactured LED dies and results in very low yield
Solution Approach 1:
The invention merges multiple individual die transfer operations into a single batch transfer operation. By using the micro contact printing plate with arrays of convex patterns that correspond to multiple micro LED die positions, the system transfers dozens or hundreds of dies simultaneously in one operation, dramatically increasing productivity while maintaining high yield through the robust batch-to-batch transfer mechanism.
3Productivity
If polymer material plate is used for micro contact printing to transfer huge number of micro LED dies, then the requirement of transferring a huge number of micro LED dies is achieved, but the polymer material plate must have both high hardness and adhesiveness to remain original shape without deformation during repeated picking up steps
Solution Approach 1:
The invention applies local quality by creating convex patterns only at the specific locations where micro LED dies need to be transferred, rather than requiring the entire polymer plate to have uniform high hardness and adhesiveness properties. The convex patterns are formed through micro contact printing, which locally modifies the plate surface to provide the necessary mechanical properties only where needed, reducing the overall complexity of material requirements.
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 method allows for the efficient and effective batch transfer of micro semiconductor structures, increasing yield and reducing the precision requirements for the carrying device, while providing a firmer connection between the micro semiconductor structures and the target substrate, suitable for various micro semiconductor devices including micro LEDs.
Implementation Method 1
each of the electrodes is eutectic bonded with corresponding one of the conductive portions of the target substrate
Data Source
AI summary
A target substrate with micro semiconductor structures is manufactured by following steps of: attaching a pre-adhesive layer on a target substrate; patterning the adhesive layer to form a plurality of micro contact protrusions; and using the target substrate to perform a selective batch pickup procedure to pick up a plurality of micro semiconductor structures so as to form the target substrate with micro semiconductor structures.