Microdevice Transfer Pads and Posts for Non-Uniform Substrates
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Solution Overview
Problem
The transfer of microdevices from a donor substrate to a receiver substrate is challenging due to existing microdevices on the receiver substrate and structural non-uniformities, which can cause damage and loss of connection during the transfer process.
Innovation Solution
A method involving the formation of a buffer layer on the donor substrate with microdevices, using pads with soft or hard material bases and soft shells on the receiver substrate to facilitate precise alignment and adhesion, and employing posts to prevent non-uniform pressure and ensure accurate transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microdevices are transferred from donor substrate to receiver substrate, then the system substrate can be populated with microdevices, but damage and loss of connection occur due to structural non-uniformities and existing microdevices on the receiver substrate
Solution Approach 1:
The receiver substrate is divided into multiple regions: existing microdevices, empty pads for new transfers, and protective posts. This segmentation allows selective transfer to specific locations without affecting existing devices, resolving the conflict between transfer productivity and connection reliability
Solution Approach 2:
A buffer layer is introduced as an intermediary between the donor substrate and receiver substrate. This buffer layer absorbs non-uniformities and prevents direct mechanical contact that could cause damage, enabling high-yield transfers while maintaining connection integrity
2Manufacturing precision
If pressure is applied to transfer microdevices, then transfer adhesion is achieved, but non-uniform pressure causes damage due to surface non-uniformities
Solution Approach 1:
Protective posts are placed beforehand on the receiver substrate at strategic locations. These posts act as cushions that distribute applied pressure uniformly, preventing concentration of stress on existing microdevices while still enabling effective adhesion for new transfers
Solution Approach 2:
A flexible buffer layer is used between substrates that can deform to accommodate surface non-uniformities. This flexible film distributes pressure evenly across the transfer interface, preventing mechanical damage while maintaining transfer precision
3Adaptability or versatility
If existing microdevices are present on the receiver substrate, then the system can be partially populated, but alignment and transfer to new pads become more difficult
Solution Approach 1:
The receiver substrate is designed with locally differentiated properties: existing microdevices in some regions, empty pads in others, and protective posts strategically positioned. This local quality differentiation enables precise alignment and transfer to specific locations while preserving existing devices, resolving the conflict between substrate adaptability and alignment precision
Data Source
AI summary
The present disclosure relates to transfer of a selected set of microdevices from a donor substrate to a receiver/system substrate while there can be already microdevices transferred in the system substrate. In particular the invention deals with pads with a hard base and soft shell. In addition, use of a stage to facilitate the microdevice transfer is detailed.