Polygonal Liquid Confinement for Immersion Lithography
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Solution Overview
Problem
In immersion lithographic apparatuses, drying stains on the substrate can cause defects and contamination due to the localized liquid supply system, leading to unpredictable effects and contamination of the substrate and apparatus.
Innovation Solution
A lithographic projection apparatus with a liquid confinement structure that confines the immersion liquid to a space adjacent the substrate, with a polygonal shape smaller than the substrate, reducing the transition zone and minimizing the occurrence of drying stains and particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a localized liquid supply system is used to provide liquid under the projection system, then the refractive index effect is improved and imaging precision is enhanced, but drying stains are formed on the substrate causing defects and contamination
Solution Approach 1:
The liquid supply system is segmented into multiple independent liquid supply units, each corresponding to a specific region under the projection system. This segmentation allows precise control of liquid distribution to different areas, ensuring uniform liquid film thickness and preventing drying stains while maintaining the refractive index effect for high-resolution imaging.
Solution Approach 2:
Each liquid supply unit provides liquid with locally optimized properties and flow rates tailored to its specific region. The system adjusts liquid supply characteristics locally across different areas of the substrate, ensuring uniform immersion conditions throughout the exposure field and eliminating drying stains that occur with uniform centralized supply systems.
2Productivity
If the substrate is scanned through the liquid during exposure, then pattern transfer is achieved, but turbulence in the liquid causes unpredictable effects
Solution Approach 1:
The liquid supply system is designed to dynamically adjust liquid flow rates and pressure during substrate scanning. The system synchronizes liquid supply with substrate movement, maintaining optimal liquid film conditions throughout the scan and preventing turbulence that would compromise exposure consistency while enabling high-productivity scanning operation.
Solution Approach 2:
The system incorporates feedback mechanisms that monitor liquid flow conditions and substrate position in real-time during scanning. Based on this feedback, the liquid supply units dynamically adjust their output to maintain stable liquid conditions, eliminating turbulence-induced variability and ensuring reliable pattern transfer throughout the exposure process.
3Device complexity
If liquid is supplied along the direction of substrate movement, then liquid distribution is simplified, but drying stains are more likely to form on the substrate
Solution Approach 1:
The liquid supply system is divided into multiple independent units distributed across the substrate width, with each unit capable of independent flow control. This segmentation replaces the single-directional supply approach, allowing liquid to be supplied from multiple locations simultaneously, which prevents the formation of drying stains while maintaining manageable system complexity through modular design.
Solution Approach 2:
The liquid supply units are asymmetrically positioned and configured relative to the substrate movement direction, with different flow rates and angles optimized for their specific locations. This asymmetric arrangement compensates for the directional substrate movement, ensuring uniform liquid distribution across the entire exposure field and preventing drying stains that occur with symmetric single-directional supply.
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 polygonal liquid confinement structure significantly reduces the time spent in the transition zone, minimizing the formation of drying stains and deposited particles, thereby enhancing the quality of the printed devices and reducing contamination.
Implementation Method 1
a liquid confinement structure configured to confine the liquid to a space adjacent the substrate
Implementation Method 2
confine the liquid to a space adjacent the substrate, wherein the space is smaller in plan than the substrate and is substantially polygonal in plan
Implementation Method 3
The polygonal liquid confinement structure significantly reduces the time spent in the transition zone, minimizing the formation of drying stains and deposited particles
Data Source
AI summary
In an immersion lithography apparatus in which immersion liquid is supplied to a localized space, the space is substantially polygonal in plan substantially parallel to the substrate. In an embodiment, two corners of the space have a radius of curvature no greater than the width of a transition zone between the space configured to contain liquid and a surrounding configured not to contain liquid.