Vertical Tether Layout for Dense Micro-Transfer Printing
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Solution Overview
Problem
Current methods for micro-transfer printing of integrated circuits face challenges in efficiently and cost-effectively transferring small, high-efficiency integrated circuits from a small, expensive source substrate to a larger, less expensive destination substrate, requiring improvements in the processes and structures for forming robust, releasable integrated circuits.
Innovation Solution
A micro-transfer-printable component source structure is developed, featuring a source wafer with a sacrificial portion and a vertical tether that connects the component to the anchor portion, allowing for controlled fracture and transfer of the component to a target substrate, reducing the horizontal extent of the structure and enabling higher areal density and reduced processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional micro-transfer printing methods are used, then integrated circuits can be transferred from source substrate to destination substrate, but the process requires extensive processing steps and the components cannot be densely packed on the source wafer
Solution Approach 1:
The vertical tether structure is pre-formed during component fabrication, with the tether extending vertically from the component through the sacrificial layer to the anchor portion. This preliminary structuring eliminates the need for subsequent complex release and transfer mechanisms, as the component is inherently designed for direct transfer upon sacrificial layer removal.
Solution Approach 2:
The invention transitions from conventional horizontal tether configurations to a vertical tether architecture. The tether extends in the vertical dimension (z-axis) rather than horizontally, allowing components to be positioned closer together in the horizontal plane while maintaining structural integrity through the vertical dimension. This dimensional change enables higher areal density on source wafers.
2Productivity
If components are placed closer together on source wafers to increase areal density, then manufacturing efficiency improves, but the structures become more difficult to manufacture with conventional methods
Solution Approach 1:
The structure is segmented into distinct functional portions: the component, the vertical tether, the sacrificial layer, and the anchor portion. This segmentation allows each element to be independently optimized and fabricated using standard photolithographic processes, simplifying the overall manufacturing of high-density arrays.
Solution Approach 2:
The sacrificial layer serves as an intermediary element that temporarily supports the component during fabrication and enables controlled release. By positioning the sacrificial layer horizontally beneath the component and the tether vertically through it, the structure facilitates easy release and transfer without requiring complex manipulation of densely packed components.
3Area of stationary object
If the horizontal extent of the micro-transfer-printable structure is reduced, then more components fit on the source substrate, but the tether connection becomes more challenging to maintain
Solution Approach 1:
The tether connection reliability is maintained by transitioning from horizontal to vertical orientation. The vertical tether extends perpendicular to the source substrate plane, creating a longer effective connection path between the component and anchor portion. This vertical configuration maintains structural integrity even when horizontal dimensions are minimized for higher density packaging.
Data Source
AI summary
A micro-transfer-printable component source structure includes a source wafer comprising an anchor portion, a sacrificial portion disposed on only a portion of the source wafer adjacent to the anchor portion, a component disposed directly and exclusively over the sacrificial portion, and a vertical tether physically connecting the component to the source wafer. The vertical tether extends from the component along a side of the sacrificial portion to the anchor portion and includes a vertical portion that extends in a direction at least partially orthogonal to a surface of the source wafer. The vertical portion can be between the component and the source wafer or adjacent to the component. Components with vertical tethers require less area on the source wafer and can be micro-transfer printed to a target substrate in closer alignment.