Intermediate Polymer Stamp for Nanoimprint Lithography
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Solution Overview
Problem
In nanoimprint lithography, the thermal expansion coefficients of imprinting materials can cause damage during replication of micrometer and nanometer structures, and the photon-imprint process requires transparency of the substrate or stamp, posing challenges in pattern transfer with minimal template wear and optimal adhesion properties.
Innovation Solution
A two-step imprint method using an intermediate polymer stamp (IPS) with a formulation containing photoinitiators, polymerizable mono- or multifunctional acrylates, epoxides, and vinyls, which forms interpenetrating networks upon curing, reducing surface energy and adhesion, allowing for efficient pattern transfer without external anti-sticking treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thermal imprint process is used to replicate nanostructures, then the pattern transfer can be achieved, but thermal expansion coefficient differences between materials cause damage to the template
Solution Approach 1:
The patent replaces the thermal imprint process with a photon-based imprint process. Instead of using heat to soften the polymer resist, UV radiation is used to initiate photopolymerization. This substitution eliminates thermal expansion issues that cause template damage while maintaining the ability to transfer nanoscale patterns with high precision.
Solution Approach 2:
The patent changes the operating parameters from thermal processing to photonic processing. By using UV-curable resin compositions with specific photoinitiators and adjusting exposure parameters (wavelength, intensity, duration), the process achieves pattern transfer without subjecting the template to thermal stress, thereby preserving template integrity.
2Reliability
If a photon-imprint process is used for pattern transfer, then template wear is minimized, but the substrate or stamp must be transparent
Solution Approach 1:
The patent introduces an intermediate polymer stamp as a mediator between the opaque substrate and the photopolymerization process. The UV-curable resin is first cured on the substrate to form this intermediate layer, which then serves as the actual template for transferring patterns to the final polymer resist. This intermediary approach allows the use of opaque substrates while maintaining the benefits of photon-based imprinting.
3Productivity
If conventional imprint materials are used, then the imprinting process can proceed, but adhesion between layers causes sticking and makes demolding difficult
Solution Approach 1:
The patent applies different surface energy characteristics to different regions and interfaces of the imprint system. The UV-curable resin composition is formulated with specific additives and functional groups that create low surface energy at the interface between the cured resin and the polymer resist, while maintaining appropriate adhesion elsewhere. This localized control of surface properties prevents sticking during demolding while preserving pattern fidelity.
Solution Approach 2:
The patent uses a composite UV-curable resin composition containing multiple components: photoinitiators for UV curing, polymerizable monomers for network formation, and surface energy modifiers to control adhesion. This composite material approach allows simultaneous optimization of curing characteristics, mechanical properties, and demolding behavior that cannot be achieved with single-component materials.
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 method achieves high replication fidelity with reduced polymer shrinkage and low adhesion, minimizing template damage and enabling easy demolding, while maintaining low interface energies for improved imprint processes.
Implementation Method 1
The Intermediate Polymer Stamp resist formulation comprises photoinitiators with the ability to initiate polymerization, polymerizable mono- or multifunctional acrylates, epoxides or vinyls
Implementation Method 2
the cured and patterned IPS resist and the substrate resist. One of the most crucial properties in the photon-based 2-step imprint process is the anti-sticking or anti-adhesion properties between both interfaces
Data Source
Figure 1a~1b
Figure 2a~2f
Figure 3a~3g
AI summary
The invention to provide curable materials, comprising photo-reactive compounds, in particular, photoinitiators and polymerizable mono- or multifunctional monomers such as acrylates or epoxides. The material may also contain fluoro-surfactants completely or partly terminated by functional groups with the ability to bind covalently to said chemical composition under curing. The curable compositions are either purely acrylate based or a hybrid of different types of monomers such as acrylates, epoxides or vinyl ethers. The polymerizable monomers may cure with the use of different types of photoinitiator, such as free radical photoinitiators or cationic photoinitiators, ultimately forming a hybrid resist comprising interpenetrating networks of different types of monomers e.g. acrylates and epoxides. The acrylate/epoxide hydrid system has showed improved replication properties in terms of high nano-imprint lithography process fidelity, due to increased conversion of acrylates and low shrinkage.