Imprint Lithography Quality Control via Optical Viscosity Assessment
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Solution Overview
Problem
Existing quality control methods for imprint lithography are time-consuming and expensive, making them impractical for inline monitoring in high-volume manufacturing processes, particularly due to the dependence on structural properties of imprintable layers which are unstable and viscosity-dependent.
Innovation Solution
A quality control method that assesses the viscosity of imprintable layers by optically analyzing the conformation of a patterned stamp with multiple sections of varying widths and depths, detecting uneven geometry through optical effects caused by light interaction with the imprinted layer, allowing for precise quantitative evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microscopy methods (SEM, AFM) are used to analyze imprintable layer structures, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical microscopy systems (SEM, AFM) with a simple optical imaging system. Instead of using expensive electron microscopy or atomic force microscopy equipment, the invention uses standard optical microscopy to capture images of the imprint pattern, thereby reducing device complexity while maintaining sufficient measurement precision for quality control purposes.
Solution Approach 2:
The patent creates an optical copy/image of the imprint pattern on the imprintable layer using standard optical microscopy. This optical copy serves as a surrogate for the physical structure, allowing quality assessment without requiring direct physical measurement through complex microscopy systems. The image captures the essential conformation information needed for viscosity evaluation.
2Measurement precision
If AFM is used to analyze imprintable layer conformation, then measurement precision is improved, but loss of time increases due to time-consuming analysis
Solution Approach 1:
The patent substitutes time-consuming AFM scanning with rapid optical imaging. Optical microscopy can quickly capture the conformation of the imprint pattern without the lengthy scanning process required by AFM, significantly reducing analysis time while providing sufficient precision for quality control through image processing and visualization.
3Measurement precision
If SEM is used for surface analysis, then measurement precision is improved, but loss of time and device complexity increase making it impractical for inline quality control
Solution Approach 1:
The patent replaces SEM with optical microscopy for surface and conformation analysis. Optical microscopy provides sufficient surface detail and conformation information at a fraction of the time and complexity, enabling inline quality control in high-volume manufacturing environments where productivity is critical.
Solution Approach 2:
The patent uses optical imaging to create a visual copy of the surface and conformation features. This optical copy captures the essential quality information needed for inline monitoring without requiring the complex and time-consuming physical scanning processes of SEM, thereby improving productivity while maintaining measurement precision for quality control purposes.
4Manufacturing precision
If viscosity of imprintable layer is directly measured, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent uses the imprint pattern conformation as an intermediary indicator of viscosity. Instead of directly measuring viscosity with complex viscometers, the invention measures the conformation quality of the imprint pattern (through optical imaging) which serves as a visual intermediary that reflects the viscosity properties of the imprintable layer, thereby simplifying the measurement system while maintaining manufacturing precision.
Solution Approach 2:
The patent substitutes direct viscosity measurement with optical conformation analysis. By using optical microscopy to visualize and analyze the imprint pattern conformation, the system replaces complex mechanical or electronic viscosity measurement devices with a simple optical imaging system, reducing device complexity while providing sufficient precision for quality control.
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
Enables rapid and cost-effective inline quality control of imprintable layers by indirectly measuring viscosity, ensuring consistent conformation to the stamp pattern and improving the quality of imprinted patterns.
Implementation Method 1
Imprinting of the imprintable layer by the stamp relief surface results from capillary forces rather than pressure to cause a redistribution (flow) of material during the contact step
Implementation Method 2
the imprintable layer solidifies due to removal of solvent from the imprintable layer by the flexible stamp
Data Source
AI summary
A method for quality assessment in imprint lithography which is based on analyzing the quality of an imprintable layer based on indirect detection of its viscosity. The method comprises imprinting a dedicated test pattern comprising multiple pattern sections, comprising pattern indentations of differing widths and/or depths. The viscosity of the imprintable layer affects how it flows to fill the lithographic imprint pattern, and higher viscosity results in uneven (at a micro or nano scale) layer geometry (i.e. curved or bowed) in each groove or on each ridge of the indentation pattern. This unevenness is detectable upon optical inspection, due to a thin-film interference pattern caused by the passage of light through the uneven imprintable layer surface, and back-reflection from an underlying substrate, this being detectable in captured optical image data. Thus, the viscosity of the imprintable layer is indirectly detectable via capturing optical image data of the test pattern. By using multiple different pattern sections of differing width and depth, a precise quantitative measure of viscosity-related quality can be identified.