High-Contrast Alignment Marks for Imprint Lithography Templates
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Solution Overview
Problem
In nano-fabrication processes, particularly in imprint lithography, alignment marks on templates made of materials with the same refractive index as the polymerizable material become invisible during the alignment process, hindering precise alignment between the template and substrate, which can lead to misalignment and errors in pattern transfer.
Innovation Solution
The use of high-contrast alignment marks formed from materials like tantalum, tantalum nitride, or silicon carbide, which are visible during the alignment process, either embedded within the template or coated on its surface, to ensure accurate positioning without the need for isolation features, allowing for precise alignment and pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If alignment marks are made from materials with the same refractive index as the polymerizable material, then the template can be made from uniform material composition, but the alignment marks become invisible during the alignment process
Solution Approach 1:
The patent applies local quality by creating alignment marks with different refractive indices than the surrounding template material. The alignment marks are formed from materials having a refractive index different from the polymerizable material, causing them to be optically distinct and visible during alignment. This local differentiation allows the marks to serve their alignment function while the rest of the template maintains uniform composition.
Solution Approach 2:
The patent utilizes optical property changes (analogous to color changes) by forming alignment marks from materials with different refractive indices. This creates optical contrast between the alignment marks and the surrounding areas, making the marks visible to alignment systems. The refractive index difference causes light to interact differently with the marks versus the background, providing the necessary visual or optical signal for precise alignment.
2Difficulty of detecting and measuring
If alignment marks are made from high-contrast materials, then alignment visibility is improved, but the template structure becomes more complex
Solution Approach 1:
The patent merges the alignment mark function with the template structure by forming the marks as an integral part of the template rather than separate elements. The alignment marks are created within the template material itself or as part of the template fabrication process, combining multiple functions (structural support and alignment reference) into a single integrated component. This reduces overall device complexity while maintaining high-contrast visibility.
Solution Approach 2:
The template structure is designed to serve multiple functions simultaneously: providing the patterning surface, maintaining structural integrity, and incorporating visible alignment marks. The alignment marks are formed as part of the template fabrication process, allowing the same structural element to serve both as a mechanical support and an optical alignment reference, thereby reducing the need for separate alignment components.
3Manufacturing precision
If alignment marks are made from high-contrast materials, then alignment precision is improved, but manufacturing complexity increases
Solution Approach 1:
The alignment marks are formed during the template fabrication process itself, before the template is used for patterning. The marks are created as part of the template manufacturing sequence, ensuring they are already in place and properly positioned when the template is deployed. This preliminary formation eliminates the need for separate alignment mark fabrication steps and ensures consistency with the rest of the template structure.
Solution Approach 2:
The patent utilizes changes in material parameters (refractive index) to create the alignment marks. By selecting materials with specific refractive index values that differ from the polymerizable material, the marks become optically distinct. This parameter-based differentiation allows for high-contrast visibility while maintaining compatibility with existing manufacturing processes, as the material selection is based on optical properties rather than complex structural modifications.
Data Source
AI summary
Imprint lithography substrates may include alignment marks formed of high contrast material. Exemplary methods for forming alignment marks having high contrast material are described.