Source Wafer Breakable Tether for Clean Micro-Transfer Pickup
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Solution Overview
Problem
Conventional micro-transfer printing (MTP) processes for integrating III-V semiconductor based devices with silicon-on-insulator (SOI) platforms face issues such as tether collapse, low yield, and debris formation due to insufficient tether strength and adhesion, leading to alignment challenges and contamination, making the process costly and inefficient.
Innovation Solution
A source wafer design with a breakable tether featuring engineered breaking regions to secure the device coupon to the substrate, ensuring strong adhesion and controlled breakage during pickup, minimizing debris and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the tether is made stronger to prevent collapse during release, then the coupon stability improves, but the pickup yield decreases because the stamp cannot pick up the coupon
Solution Approach 1:
The tether is segmented into different regions with different mechanical properties: a strong base region for stable attachment and a weak breaking region for easy separation. This segmentation allows the tether to provide stability during release while enabling successful pickup by the stamp.
Solution Approach 2:
Different regions of the tether have different local qualities - the base region has high strength and adhesion for stable attachment, while the breaking region has reduced strength to allow clean separation during pickup. This local differentiation resolves the contradiction between overall stability and local separability.
2Stability of the object's composition
If the tether adhesion to substrate is increased to prevent collapse, then the release stability improves, but debris formation increases due to tether breakage
Solution Approach 1:
The tether is designed with a dedicated breaking region that is spatially separated from the coupon structure. This segmentation ensures that when the tether breaks, the breakage occurs in a controlled location that minimizes debris generation and prevents contamination of the coupon or substrate.
Solution Approach 2:
The potential harm of tether breakage (debris formation) is converted into a benefit by designing a controlled breaking region that breaks in a predetermined location. This controlled breakage actually improves the process by providing a clean separation point that prevents uncontrolled debris generation.
3Ease of manufacture
If conventional flip-chip bonding is used for integration, then the device can be bonded into cavity, but the manufacturing cost increases and yield decreases due to alignment difficulties
Solution Approach 1:
The tether structure is prepared in advance during the coupon fabrication process, with the breaking region pre-engineered to have specific mechanical properties. This preliminary action eliminates the need for complex alignment procedures during bonding, as the tether automatically provides positional registration.
Solution Approach 2:
The tether acts as an intermediary element between the coupon and substrate, providing both mechanical support and alignment functions. This intermediary structure simplifies the integration process by eliminating the need for precise direct alignment between coupon and substrate, thereby improving manufacturing yield.
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
Enhances pickup and print yield in MTP by reducing tether-related failures and debris, facilitating precise alignment and commercial viability of the process.
Implementation Method 1
when the coupon is released via a release etch capillary force can cause the coupon to collapse
Data Source
AI summary
A source wafer for use in a micro-transfer printing process. The source wafer comprises: a substrate; a device coupon (110), including an optoelectronic device; and a breakable tether securing the device coupon to the substrate. The breakable tether includes one or more breaking regions which connect the breakable tether to the substrate.