Zero-Modulus Metastructure for Uniform Thin-Film Transfer Pressure
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Solution Overview
Problem
Existing transfer technologies, such as vacuum chuck and electrostatic chuck, damage thin-film devices due to pressure and static electricity, and struggle to provide uniform contact pressure for ultra-thin devices, leading to non-uniform adhesion and transfer issues.
Innovation Solution
A metastructure with a zero elastic modulus zone is designed, comprising a first unit capable of buckling with a negative elastic modulus and a second unit with a positive elastic modulus, synthesized to achieve zero elastic modulus in a predetermined strain zone, ensuring uniform adhesion pressure across devices with varying thickness and curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard surface transfer apparatus is used, then structural strength is improved, but contact uniformity deteriorates due to thickness differences and substrate curvature
Solution Approach 1:
The patent changes the elastic modulus parameter of the transfer apparatus from high (hard material) to low (soft material) to enable conformal contact with devices having varying thickness and substrate curvature, thereby achieving uniform contact pressure across the entire device surface
Solution Approach 2:
The patent employs a flexible transfer apparatus made of soft material that can deform and conform to the surface topology of the device being transferred, including thickness variations and substrate warpage, ensuring uniform adhesion pressure without requiring rigid structural strength
2Manufacturing precision
If a soft material transfer apparatus is used, then contact uniformity is improved, but adhesion strength deteriorates due to insufficient pressure
Solution Approach 1:
The patent optimizes the elastic modulus of the soft material to a specific range that balances flexibility for conformal contact with sufficient adhesion strength, and controls the compression strain to fall within a target zone where the metastructure maintains constant stress despite variations in device thickness and curvature
3Adaptability or versatility
If compression strain varies due to device thickness differences, then adhesion pressure becomes non-uniform, but uniform transfer requires constant stress across all devices
Solution Approach 1:
The patent designs a metastructure with specific unit cell geometries and material properties that produce a stress-strain curve with a target strain zone exhibiting approximately constant stress over a range of strains, allowing devices with varying thickness to experience uniform adhesion pressure when compressed within this target strain range
Solution Approach 2:
The patent employs composite or metastructured materials with tailored mechanical properties that enable the transfer apparatus to maintain constant stress response across a range of compression strains, accommodating devices with different thicknesses and substrate warpages while ensuring uniform contact pressure
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
The metastructure provides consistent stress in a target strain zone, ensuring uniform adhesion pressure and preventing damage to thin-film devices during transfer, even with varying device heights and substrate warpage, by maintaining constant stress levels across different strains.
Implementation Method 1
a first unit having a structure capable of buckling and having a stress-strain relation having a zone corresponding to a negative elastic modulus
Implementation Method 2
technology of attaching or transferring ultra-thin devices using van der Waals force acting on a nanoscale
Data Source
AI summary
Disclosed herein are a metastructure having a zero elastic modulus zone, which can experience constant stress in a predetermined strain zone, and a method for designing the same. The metastructure includes a first unit and a second unit, wherein the first unit has a structure capable of buckling and has a stress-strain relation having a zone corresponding to a negative elastic modulus, the second unit is disposed adjacent to the first unit and has a stress-strain relation having a zone corresponding to a positive elastic modulus, and the metastructure has zero elastic modulus in a predetermined target strain zone through synthesis of the negative elastic modulus of the first unit with the positive elastic modulus of the second unit.