Imprint Master Mold Exposure Control for Forward Taper Structures
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Solution Overview
Problem
Existing methods for manufacturing master molds for imprinting face challenges in controlling the taper angle of side shapes, requiring labor-intensive and costly operations, which hinders the formation of smaller sizes and higher aspect ratios.
Innovation Solution
A method involving a coating, exposure, and development process using masks with specific exposure amounts and types (binary or grayscale) to form resist structures with a forward taper, optimizing the taper angle based on target pattern considerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the side shapes of master mold structures are made nearly perpendicular to the base material by exposing the resist to sufficient light, then the exposure amount is increased, but the structures may temporarily deform into an inverted taper during polymerization and pressurization, causing improper transfer
Solution Approach 1:
The patent applies parameter changes by controlling the exposure amount to be equal to or less than twice Df, which changes the chemical state of the resist during exposure. This controlled parameter change ensures that the resist forms a forward taper structure that maintains its shape during subsequent polymerization and pressurization processes, preventing deformation into inverted taper while achieving proper pattern transfer.
2Reliability
If the side shapes of master mold structures are formed with a forward taper to prevent deformation, then the manufacturing process is improved, but the shapes of the recesses in the replica mold are directly reflected, making it difficult to achieve smaller sizes and higher aspect ratios if the taper angle becomes too large
Solution Approach 1:
The patent optimizes the exposure amount parameter to achieve a forward taper with an appropriate angle that balances reliability and precision. By setting the exposure amount to equal to or less than twice Df, the resist forms a forward taper structure that prevents deformation during transfer while maintaining the ability to achieve smaller sizes and higher aspect ratios in the final pattern.
3Manufacturing precision
If many complicated operations are performed to form the master mold structures into a forward taper with the target taper angle, then the manufacturing precision is improved, but the process becomes labor-intensive and costly
Solution Approach 1:
The patent applies self-service by utilizing the self-aligning and self-forming properties of the resist during exposure and development. The resist automatically forms the desired forward taper structure with the correct angle through controlled exposure to light equal to or less than twice Df, eliminating the need for complex manual operations or additional processing steps to achieve the target taper angle.
Solution Approach 2:
The patent replaces mechanical methods of forming tapers with a photochemical process. Instead of using mechanical machining or complex assembly operations to create the forward taper, the invention uses controlled light exposure to induce chemical changes in the resist that automatically form the desired taper shape, significantly simplifying the manufacturing 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
Enables the easy formation of master molds with structures having optimal taper angles, ensuring smooth pattern transfer and high yield, even under polymerization and pressurization, thereby overcoming deformation issues.
Implementation Method 1
Df: the minimum exposure amount at which the resist 3 coated on the base material 1 undergoes solarization across the entire thickness of the resist 3
Data Source
AI summary
A method for manufacturing a master mold for imprinting, with which structures formed in a desired forward taper can be formed on a base material. This method comprises a coating step in which a resist having a predetermined film thickness is coated on a base material, an exposure step in which the resist coated on the base material is exposed through a mas, and a development step in which the exposed resist is developed, the exposure step involving setting the exposure amount to be equal to or less than twice the minimum exposure amount (Df) at which the resist coated on the base material undergoes solarization across the entire thickness of the resist, and exposing predetermined portions of the resist, so that the side surface shape of the structure constituted of the resist formed by development in the development step is a forward taper.