Nanoimprint Stamp Sidewall Coating for Critical Dimension Control
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Solution Overview
Problem
Fabricating optical device structures using nanoimprint lithography is challenging due to lateral shrinkage of solvent-based resist during the curing process, which results in a reduction of critical dimensions, making it difficult to maintain the desired dimensions of optical device structures.
Innovation Solution
A method involving a stamp with an inverse optical device pattern, where a coating is applied to the sidewalls and etched to remain only on the sidewalls, allowing the solvent-based resist to be absorbed or vaporized during the cure process, thereby maintaining the critical dimensions of the optical device structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-based resist is used for nanoimprint lithography, then the curing process can be simplified, but lateral shrinkage occurs during curing which reduces critical dimension
Solution Approach 1:
The patent applies preliminary anti-action by depositing a coating on the stamp before imprinting that is designed to counteract the lateral shrinkage that will occur during curing. The coating is etched to specific patterns that will compensate for the expected shrinkage, so when the solvent-based resist cures and shrinks laterally, the final dimensions match the desired critical dimensions.
Solution Approach 2:
The patent changes parameters by modifying the stamp coating properties - specifically the coating material composition, thickness, and etch patterns - to compensate for the lateral shrinkage behavior of the solvent-based resist. By adjusting these parameters, the system achieves both simplified curing and maintained critical dimension.
2Productivity
If lateral shrinkage is allowed during curing, then the process is simpler and faster, but the critical dimension of optical device structures is reduced
Solution Approach 1:
The patent implements preliminary action by pre-patterned etching of the stamp coating before the imprinting and curing process. The coating is etched with specific geometries that will expand or contract in a controlled manner during curing to compensate for lateral shrinkage, ensuring the final critical dimension is correct without requiring slow or complex curing processes.
3Reliability
If a coating is applied to the entire stamp surface, then the stamp is fully protected, but the coating interferes with the imprinting process and pattern transfer
Solution Approach 1:
The patent applies local quality by selectively depositing and etching the coating only in specific regions of the stamp. The coating is applied to the stamp surface and then etched to leave material only in areas where protection is needed, while leaving other areas clear for proper imprinting and pattern transfer. This creates spatially varying coating properties across the stamp surface.
Solution Approach 2:
The patent segments the stamp surface into different functional zones with different coating characteristics. The coating is divided into protected regions (with coating material) and imprinting regions (without coating), allowing the stamp to simultaneously provide protection where needed and enable pattern transfer where required.
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 method effectively transfers the optical device critical dimensions to the formed structures, ensuring pattern fidelity and improving the quality of optical devices by controlling lateral shrinkage and maintaining the desired dimensions.
Implementation Method 1
allowing the solvent-based resist to be absorbed or vaporized during the cure process
Implementation Method 2
etching the inverse structure bottom and inverse structure top with an etch process having an etch direction parallel to the sidewalls such that the stamp coating remains on the sidewalls and the stamp coating is removed from the inverse structure top and inverse structure bottom
Data Source
AI summary
Embodiments described herein provide method a method of forming optical devices using nanoimprint lithography that maintains the critical dimension of the optical device structures. The method described herein accounts for lateral shrinkage of the solvent based resist during the cure process to maintain the critical dimension. The method includes disposing a stamp coating on a stamp having an inverse optical device pattern of inverse structures. The coating is disposed on sidewalls, inverse structure bottom, and inverse structure top of the inverse structures. The method includes etching the inverse structures such that the stamp coating remains on the sidewalls and is removed from the inverse structure top and bottom. The method further includes imprinting the stamp into an optical device material disposed and subjecting the imprintable optical device material to a cure process which transfers the optical device critical dimension to the optical device structures of the optical device pattern.