Nanoimprint Template Frame Window for Extrusion Control
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Solution Overview
Problem
In nanoimprint lithography, extrusions form when formable material extrudes beyond the mesa sidewalls of the template during the imprinting process, leading to defects as the extruded material cures and remains on the substrate or template, especially when the height exceeds feature size.
Innovation Solution
A method involving a template with a recessed surface coating and frame windows that expose the formable material to a gelling dose of actinic radiation before it reaches the mesa sidewalls, increasing its viscosity to prevent extrusions, combined with a curing dose to solidify the material in the central region, using a frame like illumination pattern and optical components to control the radiation distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If formable material is applied between the template and substrate during imprinting, then pattern transfer is achieved, but extrusions form when material flows beyond the mesa sidewalls
Solution Approach 1:
The patent applies a preliminary gelling dose of actinic radiation through the frame window before the formable material reaches the mesa sidewalls. This preliminary action increases the viscosity of the material at the perimeter, preventing it from flowing beyond the mesa sidewalls and forming extrusions, while still allowing complete pattern transfer within the imprint field
Solution Approach 2:
The patent creates different regions with different properties: the frame window region receives a gelling dose that increases viscosity to prevent extrusion, while the central mesa region receives a curing dose that maintains low viscosity for complete pattern transfer. This local differentiation of material properties solves the extrusion problem without compromising pattern fidelity
2Object-generated harmful factors
If the formable material viscosity is increased to prevent extrusions, then extrusion defects are reduced, but pattern formation precision may be compromised
Solution Approach 1:
The patent segments the actinic radiation exposure into two distinct doses: a gelling dose applied through the frame window to prevent extrusion, and a curing dose applied through the mesa to ensure complete pattern transfer. This segmentation allows each region to receive the appropriate dose for its specific function, maintaining both extrusion prevention and pattern precision
Solution Approach 2:
The patent changes the radiation dose parameter spatially and temporally: first applying a lower gelling dose to the perimeter region to increase viscosity, then applying a higher curing dose to the central region to ensure complete polymerization. This parameter differentiation enables simultaneous achievement of extrusion prevention and precise pattern formation
3Object-generated harmful factors
If a recessed surface coating is added to the template to control radiation transmission, then extrusion prevention is improved, but device complexity increases
Solution Approach 1:
The patent extracts the extrusion control function from the main template structure by adding a separate recessed surface coating layer with frame windows. This extracted component selectively blocks radiation in the frame area while allowing it through the mesa area, providing extrusion prevention without complicating the overall template design or fabrication process
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 effectively prevents extrusions by increasing the viscosity of the formable material, reducing flow rate and extrusion formation, allowing for precise pattern formation without defects, and facilitating timely alignment of the template with the substrate.
Implementation Method 1
A first transmittance from a back side of the template through the recessed surface coating to actinic radiation may be below a first threshold transmittance
Implementation Method 2
A second transmittance of the template from the back side of the template through the first frame window to the actinic radiation may be above the first threshold transmittance
Implementation Method 3
expose the formable material to a gelling dose of actinic radiation before it reaches the mesa sidewalls, increasing its viscosity to prevent extrusions
Implementation Method 4
A reflectance to the actinic radiation incident on the front side of the recessed surface coating may be above a second threshold reflectance
Data Source
AI summary
A frame curing template for imprinting formable material on a substrate and a system and a method of using the frame curing template. The template may comprise: a patterning surface on a mesa on a front side of the template; a recessed surface surrounding the mesa on the front side of the template; a recessed surface coating on the recessed surface. A first transmittance from a back side of the template through the recessed surface coating to actinic radiation may be below a first threshold transmittance. A first frame window may be inset within the recessed surface coating and surrounds the mesa. A second transmittance of the template from the back side of the template through the first frame window to the actinic radiation may be above the first threshold transmittance.