Component Tethers with Spacers for Micro-Transfer Printing
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Solution Overview
Problem
Current micro-transfer printing methods are inefficient and costly due to the slow release of components from source wafers, which hampers high-yield production and integration of small, high-performance integrated circuits into compact electronic systems.
Innovation Solution
A micro-transfer-printable component structure featuring a patterned sacrificial layer with sacrificial portions and anchors connected by tethers, where a spacer material etches faster than the sacrificial material, allowing for rapid release by exposing both to a common etchant, thereby forming a gap and suspending the component over the sacrificial portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common etchant is used to release components from the source wafer, then the etching process is simplified, but the release time increases and over-etching occurs
Solution Approach 1:
The sacrificial layer is segmented into two distinct portions: a first sacrificial material and a second sacrificial material with different etch rates. This segmentation allows the etching process to be divided into stages, where the faster-etching second material is removed first to release the component, while the slower-etching first material remains to prevent over-etching and damage to underlying structures.
Solution Approach 2:
Different regions of the sacrificial layer are assigned different materials with tailored etching properties. The second sacrificial material (faster etching) is positioned in specific areas where rapid release is needed, while the first sacrificial material (slower etching) is positioned in areas requiring protection from over-etching. This local differentiation optimizes both release speed and process safety.
2Reliability
If the etching process is extended to ensure complete release, then component release is achieved, but over-etching damages the substrate and anchors
Solution Approach 1:
The first sacrificial material acts as a protective cushion or buffer layer positioned beneath the second sacrificial material. During the etching process, this slower-etching material protects the substrate and anchor structures from direct exposure to the etchant, preventing over-etching damage while still allowing the component to be released through removal of the second material.
Solution Approach 2:
The first sacrificial material serves as an intermediary protective layer between the etchant and the sensitive substrate/anchor structures. It mediates the etching process by being selectively removed first or at a controlled rate, shielding the underlying structures from harmful direct etching while enabling complete component release.
3Reliability
If individually packaged components are used, then high-performance transistors are achieved, but the package size exceeds desired dimensions for highly integrated systems
Solution Approach 1:
The component is extracted from its traditional packaged form and released in an unpackaged state directly from the source wafer. By removing the protective package and using the sacrificial layer structure to protect the component during handling and transfer, the component area is dramatically reduced, enabling high-density integration while maintaining the performance benefits of unpackaged devices.
Solution Approach 2:
The sacrificial materials are discarded during the release process, allowing the component to be freed from the source wafer without requiring a permanent package. The temporary sacrificial structures enable the component to be transferred and integrated into the target substrate in its compact unpackaged form, achieving both high performance and small area.
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 approach significantly reduces the release time of micro-transfer-printable components, avoiding over-etching and enhancing the efficiency and cost-effectiveness of the micro-transfer printing process, allowing for faster and more reliable integration of components into target substrates.
Implementation Method 1
The spacer material etches faster than the sacrificial material when exposed to a common etchant, for example an etchant that etches both the spacer material and the sacrificial material in a common step or at the same time
Data Source
AI summary
A component structure comprises a substrate and a sacrificial layer comprising a sacrificial material disposed on or in the substrate. The sacrificial layer defines sacrificial portions laterally spaced apart by anchors. A component is disposed entirely over each sacrificial portion and connected to at least one anchor by a tether. A spacer comprising a spacer material is disposed in or on the sacrificial portion at least partially between the tether and the substrate. For at least one etchant, the spacer material etches faster than the sacrificial material when exposed to the etchant.