Optically Activated Chiplet Transfer System
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Solution Overview
Problem
Current methods for transferring micro-scale objects, such as chiplets, lack the ability to selectively and repeatedly move individual or subsets of objects in an arbitrary pattern, which is essential for high-yield microLED display manufacturing, as existing technologies like elastomer stamps are limited to fixed patterns and cannot handle defective chiplets effectively.
Innovation Solution
A transfer system utilizing a thermally switchable transfer layer with an optically-activated, reversible phase change material that can selectively hold and release chiplets by applying and removing optical energy, allowing for precise control over the transfer and reusability across multiple operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If elastomer stamps are used for transferring chiplets, then the transfer process is simple, but the pattern is fixed and cannot handle defective chiplets effectively
Solution Approach 1:
The patent employs a thermally-responsive polymer layer that dynamically changes its adhesion properties based on temperature. By applying heat locally through an optical energy source, specific regions of the transfer layer become compliant and release chiplets, while other regions maintain strong adhesion. This dynamic control enables selective transfer of individual chiplets or subsets in arbitrary patterns, resolving the contradiction between operational simplicity and pattern flexibility.
2Strength
If permanent bonding is used to attach chiplets, then the connection is strong, but defective chiplets cannot be replaced
Solution Approach 1:
The patent utilizes temperature as a controllable parameter to modulate the adhesion strength between the transfer layer and chiplets. At lower temperatures, the polymer maintains strong adhesion for secure transfer. When local heating is applied, the polymer transitions to a compliant state that releases the chiplet. This parameter-based control allows defective chiplets to be released and replaced while maintaining strong connections during normal operation, resolving the contradiction between connection strength and ease of repair.
3Adaptability or versatility
If selective transfer of individual chiplets is implemented, then arbitrary patterns can be achieved, but the transfer layer cannot be reused
Solution Approach 1:
The patent employs a thermally-responsive polymer that undergoes reversible phase transitions between a rigid, high-adhesion state at lower temperatures and a compliant, low-adhesion state at elevated temperatures. This reversible phase change enables the transfer layer to be used repeatedly: after releasing chiplets through local heating, the layer returns to its original state and can capture new chiplets for subsequent transfers, resolving the contradiction between selective transfer capability and reusability.
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 repeatable transfer of micro-scale objects with high precision and position registration, facilitating the assembly of microLED displays and other applications by allowing arbitrary pattern transfer and efficient replacement of defective chiplets without permanent bonding or sacrificial materials.
Implementation Method 1
An optical absorber material is located on at least one of the outward facing side of the chiplet or an inward facing side of the chiplet. An optical energy source is operable to apply optical energy to the optical absorber material through the transfer layer to selectively heat a region of the transfer layer that corresponds to a location of the chiplet.
Implementation Method 2
The transfer layer is formed of a thermally switchable material that undergoes a phase change when heated. The transfer layer is formed of a thermally switchable material that undergoes a phase change when heated resulting in the region of the transfer layer conforming to the chiplet.
Data Source
AI summary
A transfer system includes a transfer layer formed of a thermally switchable material that undergoes a phase change when heated. A side of the transfer layer is placed in contact with an outward-facing side of a chiplet during a transfer operation. An optical absorber material is located on at least one of the outward facing side of the chiplet or an inward facing side of the chiplet. An optical energy source is operable to apply optical energy to the optical absorber material through the transfer layer to selectively heat a region of the transfer layer that corresponds to a location of the chiplet. The region holds the chiplet when the optical energy is removed during the transfer operation. The region is subsequently heated during the transfer operation to release the chiplet.