Transfer Head Vacuum Control for Micro Element Handling
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Solution Overview
Problem
The existing micro element transfer methods, such as direct and indirect transfer via a transfer substrate, face challenges in reliability and cost due to the complexity of the transfer head array and limited thermal budget, which can degrade micro element performance.
Innovation Solution
A transfer head with a cavity, vacuum paths, suction nozzles, and a switching component, including a CMOS memory circuit and address electrode array, is used to control vacuum pressure for precise handling and transfer of micro elements, allowing for selective extraction and placement on a substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transfer head array is used for electrostatic extraction of micro element array, then the micro element can be transferred from donor substrate to acceptor substrate, but the transfer head structure becomes complex and reliability decreases
Solution Approach 1:
The transfer head is divided into multiple independently controllable vacuum paths, each with its own suction nozzle and valve. This segmentation allows selective extraction of micro elements while simplifying the overall control mechanism and improving reliability through modular design.
Solution Approach 2:
A cavity is introduced as an intermediary chamber that distributes vacuum pressure to multiple vacuum paths. This cavity-mediated approach replaces complex direct electrostatic extraction mechanisms with a simpler vacuum-based system, reducing transfer head complexity while maintaining extraction effectiveness.
2Ease of manufacture
If phase change is performed before extraction with transfer head array, then micro element array can be extracted, but thermal budget is limited to below 350°C (or below 200°C) to avoid micro element performance degradation
Solution Approach 1:
The invention replaces thermal phase change processes with a mechanical vacuum extraction system. By using vacuum pressure differential instead of thermal energy, the process eliminates the need for high-temperature phase change, thereby preserving micro element performance while achieving effective extraction.
Solution Approach 2:
The extraction mechanism uses vacuum pneumatic pressure applied through the cavity and vacuum paths to lift and transfer micro elements. This pneumatic approach substitutes thermal processing, allowing extraction without exceeding the limited thermal budget that would degrade micro element performance.
3Productivity
If conventional electrostatic method is used for micro element array extraction, then transfer can be achieved, but additional fabrication cost is incurred and process complexity increases
Solution Approach 1:
The cavity structure serves multiple functions: it distributes vacuum pressure to multiple paths, provides a common control point for all suction nozzles, and enables selective extraction through centralized valve control. This multi-functionality reduces the need for separate complex mechanisms for each extraction path, simplifying the overall fabrication process.
Solution Approach 2:
Multiple vacuum paths and suction nozzles are merged into a single integrated system controlled by one cavity and centralized valve array. This merging approach consolidates what would otherwise be multiple independent complex electrostatic extraction systems into a unified vacuum-based platform, reducing fabrication cost and process complexity.
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 solution enhances the reliability and efficiency of micro element transfer while minimizing performance degradation, reducing costs associated with complex transfer head fabrication and maintaining high-quality micro element performance.
Implementation Method 1
a plurality of suction nozzles, which are connected with the vacuum paths, wherein, the suction nozzles attract (e.g., hold) or release the micro element via vacuum pressure
Implementation Method 2
the address electrode array is under selective excitation by the CMOS memory circuit with voltage potential to generate electrostatic attraction, through which, corresponding movable element would deflect or approach to corresponding address electrode
Data Source
AI summary
A transfer head for transferring micro element includes a cavity; a plurality of vacuum paths connected with the cavity respectively with valves configured at the connection between the cavity and the vacuum paths and used for opening/closing; a plurality of suction nozzles connected with the vacuum paths, wherein the suction nozzles hold or release the micro element via vacuum pressure; vacuum pressure is transmitted by each vacuum path; a switching component for controlling valve to open/close each vacuum path, so as to control the suction nozzles to hold or release required micro element via vacuum pressure. Further, the switching component includes a CMOS memory circuit and an address electrode array connected to the CMOS memory circuit to realize micro-switch array. The transfer head can selectively transfer a plurality of micro elements at one time.