Immersion Lithography Fluid Handling Structure Bubble Control
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Solution Overview
Problem
In lithographic apparatuses, the inclusion of bubbles in immersion liquids during imaging processes is a significant issue, as it can lead to imaging errors and reduce the precision of pattern transfer onto substrates.
Innovation Solution
A fluid handling structure is designed with an extractor and a liquid manipulator, featuring grooves and gas knife openings to minimize the coalescence of droplets and prevent bubble formation by controlling the flow of gas and liquid, ensuring that immersion liquids remain stable and bubble-free during the imaging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the substrate is immersed in a liquid with high refractive index to improve imaging resolution, then the wavelength of exposure radiation decreases and imaging precision improves, but bubbles may form in the liquid leading to imaging errors
Solution Approach 1:
The liquid manipulator performs preliminary action by preventing bubble formation before imaging occurs. Gas knife openings create a gas flow that acts as a barrier to prevent bubbles from forming in the immersion liquid during the imaging process, addressing the harmful effect before it can impact imaging precision.
Solution Approach 2:
The gas flow from the gas knife openings acts as an intermediary between the immersion liquid and potential bubble sources. This gas barrier mediates the interaction by preventing bubbles from forming or entering the immersion liquid, thus protecting the imaging process while maintaining the high refractive index liquid's benefits.
2Ease of operation
If droplets coalesce on the surface to form larger droplets, then liquid manipulation becomes simpler, but imaging precision deteriorates due to large droplet formation
Solution Approach 1:
The liquid manipulator with grooves applies preliminary anti-action by preventing droplet coalescence before it can occur. The groove structure creates physical barriers that stop small droplets from merging into larger ones, counteracting the natural tendency toward coalescence and maintaining imaging precision while still allowing controlled liquid manipulation.
Solution Approach 2:
The surface is segmented into multiple grooves that divide the liquid handling area into separate zones. This segmentation prevents droplets from coalescing across the entire surface by confining them to individual groove sections, thereby maintaining imaging precision while enabling controlled liquid manipulation within each segment.
3Speed
If a large body of liquid is accelerated during scanning exposure, then immersion imaging can be performed, but additional powerful motors are required and turbulence occurs
Solution Approach 1:
The liquid handling system is segmented into a confined liquid space defined by the liquid manipulator and gas knife structure. Instead of accelerating a large body of liquid, only the confined portion within the grooves needs to be managed, reducing the mass that requires acceleration and thus lowering motor power requirements while maintaining scanning speed.
Solution Approach 2:
The gas flow from the gas knife openings creates a flexible gas barrier that confines the immersion liquid without requiring rigid containment structures. This flexible confinement allows the liquid to be managed in a thin film or controlled volume rather than a large body, reducing the inertia and power needed for acceleration during scanning.
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 solution effectively reduces the likelihood of bubble inclusion, enhancing the precision and reliability of the imaging process by maintaining the stability of immersion liquids and preventing the formation of large droplets that could introduce errors.
Implementation Method 1
The fluid handling structure may comprise a gas knife opening configured to form a gas knife
Implementation Method 2
an extractor comprising at least one opening arranged in a first line that, in use, is directed towards a substrate and/or a table
Data Source
AI summary
A fluid handling structure for a lithographic apparatus, the fluid handling structure successively having, at a boundary from a space configured to comprise immersion fluid to a region external to the fluid handling structure: an extractor having at least one opening arranged in a first line that, in use, is directed towards a substrate and/or a table; and a liquid manipulator on a surface that, in use, faces the substrate and/or table to reduce the chance of droplets on the surface from coalescing.