Donor Substrate Layout for Non-Interfering Micro Device Transfer
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Solution Overview
Problem
The existing micro device transfer processes face inefficiencies due to interference between micro devices on donor and receiver substrates, leading to incorrect placement and reduced utilization, especially when different types of micro devices are required for different subpixels, and the need for precise alignment and replacement of substrates.
Innovation Solution
The solution involves patterning the donor substrate with defined non-interfering and interfering areas to align micro devices correctly with receiver substrate pads, using techniques such as offsetting and varying pad sizes and orientations to prevent interference and maximize micro device utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If micro devices are densely packed on the donor substrate to increase utilization, then the quantity of micro devices increases, but interference with receiver substrate pads occurs leading to incorrect placement
Solution Approach 1:
The donor substrate is divided into multiple transfer regions, each containing a subset of micro devices. This segmentation allows the system to manage interference by processing devices in controlled groups, maintaining high utilization while preventing pad interference through regional separation of devices and their corresponding pads.
Solution Approach 2:
The system pre-identifies and marks interfering pad locations on the receiver substrate before the transfer process. By performing this preliminary analysis, the system can proactively adjust transfer parameters or select alternative devices, preventing incorrect placement before it occurs and enabling higher device density on the donor substrate.
2Quantity of substance
If the pitch of micro devices on the donor substrate is made smaller to increase device density, then the quantity of micro devices increases, but alignment precision with receiver substrate pads becomes more difficult to maintain
Solution Approach 1:
The system introduces an additional degree of freedom by allowing non-one-to-one correspondence between device pitch and pad pitch. Through the use of transfer matrices and multiple transfer regions, the system can accommodate smaller device pitches on the donor substrate while maintaining alignment precision through computational mapping rather than direct geometric correspondence.
Solution Approach 2:
The system dynamically adjusts transfer parameters including offset values, scaling factors, and region-specific transformation matrices based on the actual pitch relationships between devices and pads. This parameter adaptation allows the system to handle varying device densities and pitch ratios while maintaining precise alignment throughout the transfer process.
3Productivity
If different types of micro devices are placed on the same donor substrate to reduce substrate replacement frequency, then the productivity increases, but the complexity of managing different device types and their corresponding pads increases
Solution Approach 1:
The transfer system is designed with universal capabilities to handle multiple device types through a unified transfer matrix framework. The system can process different device geometries, pitches, and types using the same fundamental transfer mechanism, reducing the need for substrate replacement while managing complexity through standardized processing routines.
Solution Approach 2:
The system introduces a computational intermediary layer that maps diverse device types and their corresponding pads through transformation matrices. This intermediary processing layer abstracts the complexity of managing different device types, allowing the physical transfer mechanism to remain simple while the computational layer handles the diversity of device configurations.
4Adaptability or versatility
If the donor substrate is moved or repositioned during transfer to optimize device placement, then the adaptability improves, but the time required for repositioning and realignment increases
Solution Approach 1:
The system pre-calculates and stores optimal transfer matrices and repositioning parameters for different device and pad configurations. When transfer conditions change or optimization is needed, the system can quickly retrieve and apply pre-computed parameters rather than performing time-consuming real-time calculations, maintaining adaptability while minimizing repositioning time.
Data Source
AI summary
This disclosure is related to arranging micro devices in the donor substrate by either patterning or population so that there is no interfering with unwanted pads and the non-interfering area in the donor substrate is maximized. This enables to transfer the devices to receiver substrate with fewer steps.