Curable Droplet Film Formation for Bubble-Free Substrate Planarization
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Solution Overview
Problem
Conventional planarization techniques for substrates in photolithography processes, such as those used in extreme ultraviolet exposure and imprint techniques, suffer from low productivity due to the entrapment of bubbles between the mold and the curable composition, which requires a long time for bubble diffusion and affects the substrate's flatness and line width accuracy.
Innovation Solution
A film forming method involving the discrete arrangement of droplets of a curable composition on a substrate, allowing them to combine and form a continuous liquid film with solvent volatilization, followed by curing, where the average liquid film thickness is adjusted based on solvent content and curing shrinkage to achieve a flat film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mold is brought into contact with curable composition droplets on a substrate for planarization, then a flat surface can be obtained, but bubbles are entrapped between the mold, substrate, and curable composition, requiring prolonged processing time for bubble diffusion and reducing productivity
Solution Approach 1:
The curable composition is applied to the substrate before the mold contact step, allowing the composition to spread and form a continuous layer that fills surface irregularities. This preliminary action ensures that when the mold contacts the composition, bubbles are minimized because the composition is already in a favorable state for contact, thus maintaining both flatness and productivity
Solution Approach 2:
The patent controls the viscosity and composition of the curable composition to optimize its spreading behavior and bubble release characteristics. By adjusting parameters such as solvent content, polymer concentration, and additives, the composition achieves optimal flow properties that enable rapid bubble diffusion while maintaining the required surface flatness, thereby resolving the contradiction between precision and productivity
2Manufacturing precision
If curable composition droplets are discretely arranged on an uneven substrate, then the composition can fill surface irregularities, but the droplets must wait for combination and solvent volatilization before curing, extending processing time
Solution Approach 1:
The patent optimizes the solvent content and volatility characteristics of the curable composition to reduce the waiting time for solvent volatilization. By selecting solvents with appropriate vapor pressures and controlling the solvent-to-polymer ratio, the composition achieves rapid solvent evaporation while still allowing sufficient time for droplet combination, thus reducing the overall waiting time without compromising planarization quality
Solution Approach 2:
The patent employs a controlled drying process with periodic heating or air flow to accelerate solvent volatilization. This periodic action creates favorable conditions for rapid solvent removal while maintaining the droplet combination process, thereby reducing the total waiting time before curing can proceed
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 enhances productivity by reducing bubble entrapment and achieving a flat, high-quality cured film with improved mechanical properties and accuracy, addressing the limitations of conventional techniques.
Implementation Method 1
the solvent (d) contained in the liquid film volatilizes
Implementation Method 2
curing the curable composition in the liquid form after the waiting
Data Source
AI summary
The present invention provides a film forming method comprising: discretely arranging, on a substrate with unevenness, a plurality of droplets of a curable composition in a liquid form containing at least a polymerizable compound (a) as a nonvolatile component and at least a solvent (d) as a volatile component; waiting until each of the plurality of droplets discretely arranged on the substrate combines with an adjacent droplet to form a continuous liquid film on the substrate, and the solvent (d) contained in the liquid film volatilizes, and a content of the solvent (d) becomes not more than 10 vol % with respect to the whole liquid film; and curing the curable composition in the liquid form after the waiting.