Micro Element Transfer Device With Integrated Test Circuit
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Solution Overview
Problem
The challenge in micro element fabrication is efficiently transferring micro elements from a donor substrate to an acceptor substrate, particularly in ensuring the quality of the transferred micro elements and removing defects during the process.
Innovation Solution
A transfer device with a pick-up head array and a test circuit is used to test micro elements and remove unqualified ones, employing electrostatic, Van der Waals, and vacuum adsorption forces for precise handling and defect identification, with a CMOS integrated circuit for controlling the transfer process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional transfer methods (wafer bonding or electrostatic extraction) are used, then micro elements can be transferred from donor substrate to acceptor substrate, but the process complexity increases and quality control becomes difficult
Solution Approach 1:
The patent applies preliminary action by integrating test circuits into the pick-up head array before the transfer process begins. This allows micro elements to be tested for quality (electrical characteristics, optical properties) prior to transfer, enabling selective transfer of only qualified elements. The test circuits are pre-configured with test electrodes that contact the micro element electrodes, forming test loops to measure parameters without requiring separate testing steps.
Solution Approach 2:
The patent merges multiple functions into a single integrated transfer device. The pick-up head array combines the functions of: (1) picking up micro elements from the donor substrate, (2) testing the micro elements through integrated test circuits, and (3) transferring selected elements to the acceptor substrate. This consolidation eliminates the need for separate testing equipment and multiple transfer steps, reducing overall process complexity while maintaining high transfer efficiency.
2Productivity
If all micro elements are transferred without testing, then transfer speed is maintained, but quality control and defect removal become problematic
Solution Approach 1:
The transfer device performs self-service quality control by incorporating test circuits directly into the pick-up head array. As each micro element is picked up, the test circuits automatically test the element's quality parameters (electrical characteristics, optical properties) without requiring external testing equipment. This self-testing mechanism enables real-time quality assessment during the transfer process, ensuring only qualified elements are transferred while maintaining high transfer speed.
Solution Approach 2:
The patent implements preliminary quality testing before transfer by using the pick-up head's test circuits to evaluate micro elements immediately upon pickup. This preliminary action identifies defective elements early in the process, allowing them to be excluded from transfer before they can contaminate the acceptor substrate. The test loops are formed and measurements taken during the transfer operation itself, not as a separate post-transfer step.
3Reliability
If test circuits are integrated into the pick-up head, then quality control is improved, but the device structure becomes more complex
Solution Approach 1:
The pick-up head array is designed with multi-functionality, serving both as a transfer mechanism and a testing system. The test circuits are integrated directly into the pick-up head structure, allowing the same component to perform both pickup and quality assessment functions. This universal design reduces the need for separate testing equipment and simplifies the overall system architecture, as the pick-up head becomes a self-sufficient unit that can independently evaluate and select micro elements for transfer.
4Reliability
If selective transfer of qualified micro elements is implemented, then product reliability improves, but the transfer process time increases
Solution Approach 1:
The patent maintains continuity of useful action by performing quality testing and selective transfer in a continuous, integrated process. As the pick-up head array moves across the donor substrate, it simultaneously picks up micro elements, tests their quality through integrated test circuits, and transfers qualified elements to the acceptor substrate without interruption. This continuous operation eliminates idle time between pickup and transfer, and the automated testing occurs during the transfer motion itself, minimizing additional process time while ensuring only qualified elements are transferred.
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 enables the effective transfer and quality control of micro elements, ensuring only qualified elements are transferred to the acceptor substrate, improving the yield and reliability of micro element fabrication.
Implementation Method 1
The pick-up head array picks up the micro element through electrostatic force
Implementation Method 2
The pick-up head array picks up the micro element through electrostatic force, Van der Waals force and vacuum adsorption force
Implementation Method 3
The pick-up head array picks up the micro element through electrostatic force, Van der Waals force and vacuum adsorption force
Data Source
AI summary
A device configured to transfer a micro element includes: a pick-up head array configured to selectively pick up or release the micro element, and including a plurality of pick-up heads; and a test circuit having a plurality of sub-test circuits, each sub-test circuit corresponding to one pick-up head among the plurality of pick-up heads, and having at least two test electrodes for simultaneous testing of photoelectric parameters of the micro element when the transfer device transfers the micro element.